CA1297675C - Process for forming seeds capable of growing hybrid soybean plants - Google Patents
Process for forming seeds capable of growing hybrid soybean plantsInfo
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- CA1297675C CA1297675C CA000516727A CA516727A CA1297675C CA 1297675 C CA1297675 C CA 1297675C CA 000516727 A CA000516727 A CA 000516727A CA 516727 A CA516727 A CA 516727A CA 1297675 C CA1297675 C CA 1297675C
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Abstract
IMPROVED PROCESS FOR FORMING SEEDS
CAPABLE OF GROWING HYBRID SOYBEAN PLANTS
Abstract of the Disclosure An improved process is provided for forming seeds capable of yielding F1 hybrid soybean plants (i.e., hybrid soybean plants of the first filial generation) or maintain-ing male sterile soybean plants useful in the production of male fertile F1 hybrid soybean plants. Male sterile soybean plants (i.e., seed parents) and the male fertile soybean plants (i.e., pollen parents) are caused to undergo cross-pollination with the aid of pollen-carrying bees under conditions wherein pollen transport from the male parents to the female parents is significantly increased. Such pollen transfer is enhanced by growing the parent soybean plants at a location where natural rainfall is limited when soybean flowering occurs during the summer, applying water via irrigation as required to promote normal plant growth up to at least the time of the onset of flower formation, and withholding irrigation water at the appropriate time to induce enhanced nectar flow within the soybean flowers and render the soybean flowers highly attractive to bees. In accordance with the concept of the present invention the pollen-carrying bees (e.g., honeybees) which are strongly attracted to the enhanced nectar flow within the soybean flowers concomitantly facilitate a high level of cross-pollination and seed are formed on the male sterile soybean plants which ultimately are harvested.
CAPABLE OF GROWING HYBRID SOYBEAN PLANTS
Abstract of the Disclosure An improved process is provided for forming seeds capable of yielding F1 hybrid soybean plants (i.e., hybrid soybean plants of the first filial generation) or maintain-ing male sterile soybean plants useful in the production of male fertile F1 hybrid soybean plants. Male sterile soybean plants (i.e., seed parents) and the male fertile soybean plants (i.e., pollen parents) are caused to undergo cross-pollination with the aid of pollen-carrying bees under conditions wherein pollen transport from the male parents to the female parents is significantly increased. Such pollen transfer is enhanced by growing the parent soybean plants at a location where natural rainfall is limited when soybean flowering occurs during the summer, applying water via irrigation as required to promote normal plant growth up to at least the time of the onset of flower formation, and withholding irrigation water at the appropriate time to induce enhanced nectar flow within the soybean flowers and render the soybean flowers highly attractive to bees. In accordance with the concept of the present invention the pollen-carrying bees (e.g., honeybees) which are strongly attracted to the enhanced nectar flow within the soybean flowers concomitantly facilitate a high level of cross-pollination and seed are formed on the male sterile soybean plants which ultimately are harvested.
Description
Back~round of the Invention It i5 well known that when different plant lines are cross-pollinated one can achieve in the offspring a highly desirable heterosis or hybrid vigor which advantageously provides increased yields of the desired crop.
Soybeans (l.e., seeds of Glycine ~ax plants) are recognized to be an important crop in many parts of the world.
For instance, approximately 65 to 75 million acres of soybeans are planted annually in the United States which establi3hes this to be the largest seed crop presently grown in the United States. Various approaches to the production of hybrid soybeans are disclosed in United States Patent Nos. 3,903,645 and 4,077,157, and in my copending Canadian Serial No. 475,718.
Also, technical articles which discuss the existance of some degree of sterility in soybeans and the formation of hybrid soybean seeds are identified in my copending Canadian Serial No. 475,718.
It is an object of the present invention to provide an improved process for producing seeds capable of forming Fl hybrid soybean plants wherein pollen-carrying bees are employed to accomplish the required pollen transfer.
It is an object of the present invention to provide an improved process for maintaining male sterile soybean plants useful in the production of male fertile Fl hybrid soybean :
plants wherein pollen-carrying bees are employed to accomplish the required pollen transfer.
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It is an object of the present invention to provide an improved process for producing seeds capable of forming Fl hybrid soybean plants wherein the required visitatlon between the parent plants by pollen-carrying bees is promoted on a highly effective basis.
It is another object of the present invention to provide an improved process ~or maintaining male sterile soybean plants useful in the production of male ~ertile F
hybrid soybean plants wherein the re~uired visitation between the parent plants by pollen carrying bees is promoted on a highly effective basis.
It i~ a further ob;eck of the present invention to provide an improved process for producing seeds capable of forming Fl hybrid ~oybean plants wherein the seed product is caused to set in increased yields.
These and other objects as well as the scope, nature, and utilization of the claimed invention will be apparent to those skilled in the art from the following detailed description and appended claims.
Summary of the_Invention It has been ~ound that an improved process for the efficient production of seeds capable o~ growing Fl hybrid Glycine max comprises:
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially uniform population of male sterile soybean plants in pollinating proximity to a ubstantially uni~orm population of male fertile soybean plants which when crossed with the male sterlle soybean plants enable the ~ormation o~ seeds on the male sterile ~oybean plants which are capable of growing male fertile Fl hybrid soybean plants, (b) applying water via irrigation to the substan-tially uni~orm populations of soybean plants of step (a) as required to promote normal ~ plant growth up to at least the time of the onset of ~lower formation within each of the populations, (c) withholdin~ irrigation water from the plants : of the substantially uni~o~m populations at a ~ime when flowers are present within each of the substantially uniform population~ ~or a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within the flowers which serves to render the ~lowers mora a~tractive : : ~ to bees, (~d? crossing the male sterile soybean plants and the male ~ertile soybean pla~ts with the aid :~ . of pollen-carrying bees which are attracted ;:
to the enhanced nectar ~low whereby seeds are ; .
:: ~ormed on the male sterile soyb~an plants, and (e) selectively recoveriny the seeds which have ~ormed on the substantially uniform popula-tion o~ male sterile soybean plants.
,:
~, It has been found that an improved process for the afficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile Fl hybrid Glycine max plants comprises:
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the su~mer a sub~tan-tially random population of male sterile soybean plants and male ~ertile soybean plant~ which when crossed with the male sterile soybean plants enable the ~ormation of seads on the male sterile soybean plants which are capable of growing male fertile F
hybrid soybean plants, (b) applying water via irxiyation to the substan-tially random population of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of ~lower formation, (c) withholding irrigation water from the plants of the substantially xandom population at a time when flowers are present for a period of time durin~ which no appreciable natural ' rainfall occurs so as to induce enhanced nectar flow wikhin the ~lowers which serves to render the flowers more attractive to bees, (d) pollinating the substantially random popula-tion of soybean plants with the aid o~
: pollen-carrying bees which are attracted to ~4-the enhanced nectar ~low whereby seedR are formed on the male sterile plants which are capable of growing male fertile Fl hybrid soybean plants and saeds are formed on the male fertile soybean plants as a result of self-pollination, and (e) recovering seeds which have ~ormed on the subs~antially random population of soybean plants.
It has been found that an improved process for maintaining male sterile ~ B~ ~3~ plants useful in the production of male fertile Fl hybrid soybean plant~ compri-ses:
(a) growing at a location whlch normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a ~ubstan-tially uniform population of cytoplasmically , male sterile soybean plants in pollinatlng i proximity to a substantially uniform popula-ion of male fertile main~ainer soybean plants which when cros~ed wlth the cytoplas-mically mal~ sterile soybean plants enable the forma~ion of seeds on the cytoplasmically male sterile plants which are capable of : growing addi~ional cytoplasmlcally male ~ .
sterile pl2nt5, ~; ~ (b~ applying wa~er via irriga~ion to the ~ubstan-tially uniform populations of soybean plants : - of step (a) as required to promot~ normal :~
_5_ .
plant growth up to at least the time of the onset of ~lower formation within each of the populations, (c) withholding irrigation water from the plants o~ the substantially uniform populations at a time when flowers are present within each of the substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so a~ to induce enhanced nectar flow within the flower~ which serves to render the flowers more attractive to bees, (d) crossing ~ha cytoplasmically male sterile soybean plants and the male fertile main-tainer soybean plants with the aid of pollen-carrying bees which are attracted to the enhanced nectar flow whereby seeds are formed on the male sterile soybean plants, and (e) selectively recovering the seed~ whioh have formed on the substantially uniform popula-tion of cytoplasmically male ~terlle soybean plants.
, ;~ Detailed Descripti n of the Inventi_n In accordance with the con~ept of the present in~ention it is essential tha~ the parent ~oybean plants be : gxown at a location which normally experiences limited natural rainfall during the summer months when soybean flower~ normally are ~ormed and cross-pollination is carried -6~
~2~ i75 out with the aid of pollen-carrying bees. Natural rainfall when soybean flowers are preaent can adversely impact upon the enhanced nectar flow within the soybean flowers made possible in the improved process of the present invention.
Accordingly, the location where the process of the present invention is carried out generally will be dif~erent than those areas where soybean plants customarily have been grown in the past. For instance, the bulk of those areas of the United States pr~viously devoted to the growing of soybeans for commercial crops and seeds will be unsuitable for hybrid seed production in accordance with the concept of the pre~ent invention. If the planting area experiences significant rainfall during the summer months when soybean ~lowers are present, this will introduce an element of unpredictability which will make it infeasible to attempt to implement the concept o~ the present invention. Such rain~all at an inappropriate time will destroy the highly e~fective enhanced pollen transfer among soybean plants as provided herein.
The location selected for growing the soybean plants may be one which experiences (1) limited natural rainfall throughout the entire year, or (2) li~ited natural rainfall during the summer months when soybean flowering capable of producing cross-pollination occurs ~i.e., soybean flowers are present on each parent~ and more plentiful xainfal1 at other times during the year.
In a preferred embodiment of the present invention the location selected to grow the soybean paxent plants will normally experience les~ than 4 inches o~ rainfall when soybean flowering occurs during the summer ~ e., the --7~
~25~7~7~
average natural rainfall for the past 10 years will be less than 4 inches when soybean flowering simultaneously occurs on each parent during the 3 summer months). In a particularly preferred embodiment of the present invention the location selected to grow the soybean parent plants will normally exper-ience less than 2 inches of rainfall (e.g., less than 1 inch of rain) when soybean flowering occurs during the summer (i.e., the average natural rainfall for the past 10 years will be less than 2 inches when soybean flowering simultaneously occurs on each parent during the 3 summer months).
In the United States the improved process of the present invention commonly will be carried out in relatively dry areas which are generally west of those where soybean plants customarily are grown. For instance, limited areas from within the Great Plains may be selected extending from South Dakota, eastern Wyoming, Nebraska, eastern Colorado, western Kansas, the Oklahoma panhandle, eastern New Mexico and western Texas which commonly are irrigated from the vast underground Ogallala Aquifer. See, "Plant Stress and Water Conservation Research Program: A Progress Report" published by the College of Ayricultural Sciences, Texas Tech University, Lubbock, Texas (1984) at Page 7 for a map which illustrates the location of the Ogallala Aquifer. The drier areas of Nebraska, Kansas, and western Texas are particularly suited for carrying out the improved process of the present invention.
Representative counties served by the Ogallala Aquifer where the process of the present invention can be ; - 8 -g~
carried out to particular advantage includa the South Dakota counties o~ Shannon, Bennett, Todd, Tripp, Gregory, and Gillette; the Wyoming counties of Converse~ Laramie, Platte, Goshen, and Niobrara; the N~braska counties of Dawes, Box Butte, Garden, Kimball, Morrill, Cheyenne, Sheridan, Banner, Scotts Bluff, Keith, Arthur, McPherson, Grant, Cherry, Hooker, Thomas, Deuel, Keya Paha, Perkins, Chase, Dundy, Hitchcock, Red Willow, Hayes, Frontier, Lincoln, Logan, Loup, Garfield, Holt, Rock, Valley, Greely, Sherman, Howard, Buf~alo, Hall, Gosper, Phelps, Kearney, Furnas, Harlan, Franklin, Webster, Adams, Wheeler, Antelope, and Boone; the Colorado counties oE Sedgwick, Phillips, Logan, Weld, ~organ, Washington, Yuma, Kit Carson, Cheyenne, Kiowa, Prowers, Baca, Las Animas, Bent, Otero, Crowley, and Lincoln; the Kansas counties of Cheyenne, Rawlins, Sherman, Thomas, Decatur, Sheridan, Norton, Phillips, Graham, Wallace, Logan, Greeley, Wichita, Scott, Ness, Hamilton, Kearney, Finney, Stanton, Grant, Ha~kell, Gray, Ford, Hodgman, Morton, Stevens, Seward, Mead, Clark, Kiowa, Comanche, Edwards, Pawnee, Pratt, Staf~ord, Barton, Rice, Reno, Kingman, McPhereson, Harvey, and Sedgwick; the Oklahoma counties of Cimarron, Texas, Beaver, Harpar, Woodward, Roger Mills, and Dewey; the New Mexico counties of Curry, Roosevelt, Chaves, L~a, and Quay; and the Taxas countie~ o~ Hartley, Dallam, Sherman, ~oore, Hansford, Hutchinson, Carson, Roberts, Hemphill, Gray, Wheeler, Deaf Smith, Randall, Armstrong, Donley, Parmer, Castro, Swisher, Briscoe, Bailey, Lamb, Hale, Floyd, Motley, Cochran, Hockley, Lubbock, Crosby, Dickens, Yoakum, Terry, Lynn, _g _ 7~7~
Garza, Gaines, Dawson, Andrews, Martin, Mitchell, Ector, Midland, and Glasscock.
The thirteen counties of northeastern Arkansas (i.e., Clay, Craighead, Cross, Crittenden, Greene, Independence, Jackson, Lawrence, Mississippi, Poinsett, Randolph, White and Woodruf~) are well suited for carrying out the process of the present invention since rainfall normally is limited at that location during the summer months.
Other illustrative areas in the United States where the process of the present invention conveniently can be practiced include the irrigated areas of Idaho, Oregon, Washington, California, etc.
Illustrative areas outside of the United States where the process of the present invention conveniently can be practiced inalude Argentina, Brazil, Chile, Mexico, Canada, Egypt, South Africa, Sudan, Turkey, U.S.S.R., India, People~' Republic o~ China, Australia, New Zealand, etc.
~ It should be understood, however, that the process :~ of the present invention can be carried out at any location in the northern or southern hemisphQres where the ~oil will support the growth o~ soybean plants, limited rainfall occurs during the summer, and irrigation water is available to promote normal plant growth~
It is preferred that the area selected be one in which.th~re is a relatively low pestlcide usage, honeybees customarily are kept and are available, and a wild be~
population is available.
The key parent soybean plants whi~h are grown in accordance with the concept of the present invention are male sterile soybean plants that serve as the seed parents and male fertile soybean plants that serve as the pollen parents.
The male sterile soybean plants are fully female fertile, but yield no viable pollen that produces unwanted self-pollination.
These male sterile soybean plants serve as the female parents following the required cross-pollination. Accordingly, all of the seed formed on the male sterile soybean plants following pollination will be capable of forming the desired soybean plants. The male sterilit~ of the male sterile soybean plants can be of varied causation. For instance, such plants may be cytoplasmically male sterile or genetically male sterile.
Alternatively, such plants may be rendered male sterile through the application of a chemical which destroys the ability of the plants to yield viable pollen (l.e., a gametocide). Represent-ative gametocides include FW45~ available from Rohm & Haas Co., I'D-1123 available from Pennwalt Corp., potassium 3,4-dichloro-5-isothiazolecarboxylate, 2,3-dichloroisobutyric acid and the water soluble salts thereof (e.g., sodium 2,3-dichloroisobuty-rate available from Rohm & Haas Co.), etc.
In accordance with a preferred embodiment of the present invention, the male sterile plants are cytoplasmically male sterile plants as described in my copending Canadian Serial No. 475,718. As described in such copending Applica-tion, three factors found to exist in available sources of Glycine max plants, when properly combined in a single plant by the intervention of man, provide an effective starting plant to accomplish the hybrid soybean production. Such factors (as described hereafter) L` '' t-have heretofore existed separately while dispersed in soybean plants from widely differing sources. The female fertile male sterile soybean plants possess (1) a Cms cytoplasm, ~2) a distinct pair of recessive rlrl genes in the cell nucleus, and (3) a distin~t pair o~ recessive r2r2 genes in the ce'l nucleus, which in combination render the plant incapable of producing viable pollen while otherwise carrying out the usual plant functions required to produce soybeans if viable pollen is provided ~rom another soybean plant.
Glycine max plants are self-destructing annuals which cannot be satisfactorily propagated by asexual means since if new plant~ are formed by cuttings, the new plants ars of a progressively smaller size. The preferred female fertile male sterile soybean plants can be successfully propagated (i.e., maintained) by sexual means as described hereafter. Also, these male sterile plants unlike soybean plants which rely exclusively on nuclear genes for ~terility -can be conveniently perpetuated or maintained without unwanted segregation with respect to sterility, as described herea~ter.
The atypical Cms cytoplasm of the preferred female fertile male sterile soybean plants can be derived through the female parent ~rom an appropriate cytvplasmic sour~e.
For instance, i~ has been found that the Cms cytoplasm r $uired in the female ~ertile ~ully male sterile soybean plants can b~ con~aniently derived from a Mandarin cytoplas-mic ~ource through the female parent. Many Northern ~oybean varieties are derived from this cytoplasmic source. Plants of this origin have been found inherently to po ~eR~ an ~ ~ 'S~`? ~
atypical cytoplasm of the type required to practice thepresent invention. Since this required ~actor is not contributed by nuclear genes and is not transmitted through the pollen, it can be considered cytoplasmic, non-Mendelian, extrachromosomal, uniparental, and maternal.
Representative commercially available soybean plants which are derived maternally from a Mandarin cytoplasmic source are ~delphia, Chippewa, Chippewa 64, Clark, Classic I, Classic II, Columbus, Cutler, Disoy, Elf, Ford, Grant, Harosoy, Harosoy 63, Hobbitt, Kent, Lincoln, Lindarin, Lindarin 63, Magna, Prize, Provar, Rampaga, RA 203, RA 402, RA 4~1, RAX 56, RAX 57, RAX 61, RAX 62, RAX 66, SB 27, Shelby, Traverse, Wayne~ Wirth, Williams, etc. A particu-larly good source for the re~uired Cms cytoplasm has been ~ound to be the El~ variety which was introduced during 1977 by AR-SEA-USD~, the Ohio Agric. Res. and Dev. Center, and the U. of Illinois Agric. Res. Station. In 1981 this variety was registered by the Crop Sci. Soc. of Am. as Reg.
No. 150.
It should be emphasized that when plants of the above-identified varieties are inspected for the possible absencQ o~ viable pollen production, that male aterile plants (either partially male sterile or completely male sterile~ wherein the sterility is attrikutable to the cytoplasm are not observed. It has been found that such sterility is not expressed even though the required atypical Cms cytopla m is presen~ because it is not in combination with the requirad recessive genss di cussed hereafter.
Instead such varieties can be shown to posses~ at least one pair o~ dominant RlRl or R2R2 genes (usually both pairs) -~$ ~,Y~ ~
which always leads to the expression of the usual viable pollen production even in the presence o~ the Cms cytoplasm.
The pair of recessive genes rlrl for male ster-ility present in the preferred female fertile fully male sterile plants employed in the process o~ the present invention can be derived through its male parent from a ~irst gene source which possesses such genes. Unlike the male ~terile plants, the ~irst gene source may possess a usua~ N cytoplasm which can be termed a "normal" or "neu~
tral" cytoplasm. When such cytoplasm is present, cytoplas-mically controlled male sterility is not ~xhibited regard-less o~ the nuclear genes which are present.
It has been found that the requisite pair of rlrl rQcessive genes ln tha cell nucleus of the ~emale fertile fully male sterile soybean plants conveniently can be derived ~hrough the male parent from a Dunfield germplasm base. Many Southern soybean variQties are derived from this germplasm base. Plants of this origin hav~ been found inherently to possess the required pair of recessive genes which has been designated rlrl. Representative commercially available soybean plants ~rom which the r1rl recessive genes may be derived are Bedford, Bethel, Centennial, Dare, Dyer, Forrest, Hill, Klrby, RA(d)41, RA 581, RA 603, RA 60~, RA
606, R~ 680, Tracy, Wabash, York, etc. A particularly good source for the rlrl recessive genes has been found to be the Bedford variety which was introduced during 1978 by FR-SEA-USDA, and the Tennessee and ULssissippi Agric. ~xpt.
Stations. This variety was re~istered by the Crop Sci. Soc.
of Am. as Reg. No. 118.
b ~
It further should be emphasized that when plants of the above-identified varieties having rlrl genes are inspected for the possible absence of viable pollen produc-tion, that male sterile plants (either partially male sterile or completely male sterile) wherein the sterility is attributable to the cytoplasm are not observed. It has been found that such sterility will not be expressed unless tha atypical Cms cytoplasm is present along with recessive genes r2r2. Instead such varieties can be shown to possess dominant R~R2 genes which restore male fertility.
The pair of recessive genes r2r2 for male steri-lity present in the preferred female ~ertile fully male sterile plants can be derived through its male parent from a second gene sourca which possesses such genes. Such r2r2 genes are present as a distinct gene pair apart from the rlr1 genes in the female fertile fully male sterile plants (i.e., they are present at di~ferent loci). Unlike the male sterile plants, the second gene source may possess a usual N
cytoplasm which can be termed a "normal" or "neutral"
cytopl~sm. As previously indicatad, when such cytoplasm is present oytoplasmically controlled male sterility is not exhibited regardless of the nuclear genes which are pres nt.
It has been found that the requisite pair of r2r2 recessive genes in the cell nucleus of the perferred female fextil~ ~ully male sterile soybean plants conveniently can be derived through the male parent from a Tokyo germplasm base. ~any Southern soybean varietie~ arQ derived from this germplasm basa. Plants of this origin have been ~ound inherently to possass the required pair of recessive genes which has been designated r2r2. Represantative commercially ~ 2~ 5 available soybean plants from which the r2r2 recessive genes may be derived are Bragg, Braxton~ Cobb, Govan, Hampton, Hampton 266, Hardee, Hutton, Jackson, Kirby, Majos, Ogden, RA 604, RA 701, RA 800, Volstate, Wright, etc. A particu-larly good source for the r2r2 recessive genes has been found in thQ Braxton variety which was introduced during 1979 by the USDA and various state Agric. Expt. Stations.
It additionally should be emphasized that when plants of the above identified varieties having r2r2 genes are inspected ~or the possible absence of viable pollen production, that male sterile plants (either partially male sterile or completely male sterile) wherein the sterility is attributable ta the cytoplasm are not observed. It has been ~ound that such sterility will not be expressed unless the atypical Cms cytoplasm is present along with recessive genes rlrl. In~tead such varieties can be shown to possess dominant RlR~ gene~ which restore male fertility.
The pre~erred female fertile fully male sterile plants can be maintained or perpetuated in spite of the male sterility by crossing with pollen ~rom a soybean plant which posse~ses an N oytoplasm and the two distinct pairs of recessive genes rlrl and r2r2. Such preferred maintainer plants are formed by the intervention of man through the comblnation of the required ~ackors and are not found in nature. The progeny sf this cross will again be ~emale fertile and fully male sterileO Also, should the perferred female ~rtile fully male sterile plants be crossed with pollen from a male fertility restorer (i. , having domin~nt RlRl genes and/or dominant R2R2 genes), then the progeny will be fully fertile Fl hybrid soybean plants. Suitabla male fertility restorer plants are readily available withoutmodification. For instance, any of the varieties heretofore named can perform this function. The only requirement is that plants which supply the pollen possess at least one pair o~ the required dominant fertility restoring genes.
The development of preferred f~male fertile fully male sterile soybean plants for use in the present inven-tion, as well as preferred maintainex plants for the same, can be exempli~iad through a plant breeding program employ-ing plants of the Elf, Bed~ord, and Braxton varieties. It should be understood, however, that the preferred embodiment of the present process can be equally well practiced through the utilization of soybean plants of other varieties provided the essential criteria set forth herein neverthe-less arè met. Initially plants of the Bedford variety (i.e., having an rlrl gene source) are crossed by hand with pollen from plants of the Braxton variety (i.e., having an r2r2 gen~ source). The progeny of thls cross are f-llly female fertile and male fertile and serve as a pollen source ~or plants of the Elf variaty (i.e., having a Cms cy~oplas-mic source). Such crossing to the Elf variety is again carried out hy hand under controlled conditions in the absence of Elf self-pollination. When the Fl seed which has fo~med on the Elf female parent is grown, it will be noted that all of the resulting plants are fully female fertile and male fertile. Each of these Fl plant~ is next se}f-pollinated through succeedin~ generations to form F2, F3, and F4 controlled populations which are inspected ~or the absence of viable polLen. It i5 observed that some plants are female fer~ile fully male fertile, som plants are female fertile partially male fertile (i.e., produceonly a limited quantity of viable pollen), and some plants are ~emale fertile fully male ~terile (i.e., produce no viable pollen).
The fact that none of the F1 plants were male sterile in this preferred embodiment aonfirms that the stsrility subsequently observed was not controlled solely by nuclear genes. The ratio~ in which the plants segregate in the F2, F3 and F4 generations with respect to male sterility confirm that the sterility is cytoplasmic in nature and the result o~ a more complex cytoplasmic/genetic system in which the genetic aspect is bifackorial (i.e., two distinct gene pairs at different loci are operative and are interacting with the cytoplasm). The ~ully male sterile plants possess the Cms cytoplasm and the rlrl and r2r2 genes. The par-tially male sterile plants possess the Cms cytoplasm and (l) Rlrl and r2r~ genes or (2) rlrl and R2r2 genes. The f`ully male fertile plants possess the Cms cytoplasm and RlRl genes and/or R2R~ genes. When the ~ully male sterile plants are crossed with pollen from the Elf, Bed~ord, and Braxton varieties, all F1 progeny are fully male fertile~
Accordingly, this indicates that no single parent variety (l.e., Elf, Bed~ord, or ~raxton) possesses sufficient genes to create male sterile Fl plantq.
Once the preferred mals st~rile plants are on hand, suitable maintainer plant~ (i.e~, those having an N
cytoplasm in combination with rlrl and r2r2 genes) can be devèloped by ~tandard plant bre~ding techniques lnvolving intercros~ing and introgre sion. For instance, tha required rlrl and r2r2 g~nes can be provided in existing soybean ~ ~,4~ $
varieties of agronomic importance having khe usual Ncytoplasm by intercrossing and possible backcrossing by hand with the pollen derived from female fertile partially male fertile plants obtained from the F2, F3 and F4 controlled populations obtained during or subse~uent to the development of the male sterile plants (described above). The Fl plants from this cross are grown and are self~pollinated to form F2 plants. Test cros~es of the fully male sterile plants pre~iously developed with pollen derived from the F2 plants are made and those plants are identified and preserved which are capabls of yielding fully male sterile Fl progeny. Such plants possess the full complement of recessive rlrl and r2r2 genes. Once identified such preferred homozygous maintainer plants can ~Q perpetuated by self-pollination.
When producing seeds capable of growing male fertile Fl hybrid soybean plants in accordanc~ with one embodiment of the process of the present invention, the required male sterile soybean plants are grown at an appropriate location as a substantially uniform population in pGllinating proximity to a substantially uniform popula-tion of male fertile soybean plants. In the context of the present invent~on "pollinating proximity" specifies tha~ the two types o~ parent plants are sufficiently near that pollen can be tran~fexred by pollen-carrying bees without loss of its viability. The male ~ertile soybean plants conveniently can be a pure line variety. For instance, the two types of plants can be grown adjacent to ~ach other as alternating strips. In a preferred embodiment approximately 2, 4, or 6 rows o~ the male sterile soybean plants form a substantially uni~orm population and alternate with a substantlally uniform population of approximately 2 rows of the male fertile soybean plants. Following pollen transfer from the male ~ertile soybean plants to the male sterile plants (as described hereafter3, seeds are formed on the male sterile soybean plants. The male fertile soybean plants commonly are self-pollinated and seeds also form on them. At harvest time the seeds are selectively recovered from each of the substantially uniform plant populations. Accordingly, the seeds which are recovered from the male sterile soybean plants are a substantially homogeneous assemblage of saeds which upon growth yield male fertile Fl hybrid soybean plant~.
In accordance with another embodimenk of the process of the present invention, a substantially uniform binary seed blend is formed containing a substantial proportion (e.q., at least one-half by number) of seeds capable of growing male fertile Fl hybrid soybean plants.
Such blend can be formed by growing at an appropriate location a substantially random population of male sterile soybean plants together with the male fertile soybean plants. For instance, approximately 75 to 95 percent (e.a., approximately 90 percent) of the plants in the random population can be male sterile plants and approximately 5 to 25 percent (e.g~, approximately 10 percent~ of the plants in the random population can be the male fertilQ soybean plants. Following pollen trans~er the seeds formed on the mal~ stsrile soybean plants are capable of forming the male fertil~ Fl hybrid soybean plants, and the seede formed on the restorer soybean plants are the result of self-pollina-tion. The resulting seeds formed on the subs~antlally -20~
76~
random population of soybean plants next are harvested in bulk and can be planted in bulk by the grower.
The level of cross-pollination occurring in the random population of plants (discussed hereafter) can be visually observed by inspecting the resulting seeds or the plants produced when the resulting seeds are grown if one incorporates an appropriate genetic marker system into the parent plants which gives one appearance upon cro~s-pollina-tion and another appearance upon self-pollination. The genetic marker can take the form o~ a recessive gene which expresses itself upon self-pollination, but which is dominated by another gene giving a different appearance when cross-pollination takes place. Under such circum-stances the male ~ertile plants could be homozygous rece~-sive for such trait and the male sterile plants homozygous dominant for such trait. For instance, the genetic marker can be a distinctive pubescence color (e.q., gray pubescence vs. tawny pubescence~, ~lower color (e.q., white flowers vs.
purple flowers~, seed pod color (e.q., tan vs. brown pods3, hilum appearance (~, yellow vs. black hilum or bu~f vs.
black hilum), etc.
Alternatively, cytoplasmically male sterile soybean plants use~ul in the production of male fertile F
hydrid soybean plants can be maintained, perpetuated/ and multiplied by planting a substantially uniform population of th~ same in pollinating proxim~ty to a substantially uniform population o~ the maintainer soybean plants which when crossed with the male sterile ~oybean plants enable the formation o~ seeds on the cytoplasmically male st~rile ~oybean plants which are capabl~ of growing additional 7 ~
cytoplasmically male sterile plants. For instance, the twotypes of plants can be grown adjacent to each other as alternating strips as described earlier with respect to the production of male ~ertile Fl hybrid seed. Following pollen transfer (as described hereafter) from the maintainar soybean plantq to the male sterile soybean plants seeds ~re formed on the male sterile ~oybean plants. The maintainer plants are self-pollinated and seeds also ~orm on them. At harvest time the seeds are selectively harvested from each of the substantially uniform plant populations.
Accordingly, the seeds which are recovered from the male sterile soybean plants are a substantially homogeneous assQmblage of seeds which upon growth yield cytoplasmically male sterile soybean plants. The seeds which are selec-tivaly recovered ~rom the maintainer plant~ can be planted to produce additional maintainer plants or sold as a commercial soybean product.
Since the photosensitivity of soybean plants tends to vary among soybean varieties, it is important for best results that the parent soybean plants (i.e., the male sterile soybean plants and the male fertile soybean plant~) each possess a day length sensitivity ~i-e-, a photoperiod response) which generally corresponds to that of the location (i.e., the latitude or di~tance ~rom the equator) where the soybean plants are grown when carrying out the proces~ o~ the present invention as well as to the area wh~re the seed product i5 ultimately to be grown. Fox instance, the parent plant~ and the ultimate seed product preferably should posses~ a photo~ensitivity within plus or minus one maturity group unit o~ the locations where grown.
Additionally, for optimum results the locations where grown should correspond exactly -to the maturity groups of the plants involved. See, Chapter 6 by Edgar E. Hartwig of "Soybeans:
Improvement, Production, and Uses", American Society of Agronomy, Inc., Pages 189 to 190 (1973), for a discussion of soybean maturity group units and their significance. For in-stance, if a soybean variety which grows well at a southern latitude is grown at a northern latitude, the longer days may cause the soybean plants to grow excessively tall and to tend to lodge. Alternatively, if a soybean variety which grows well at a northern latitude is grown at a southern latitude, the shorter days may cause limited plant growth (i.e., heigh-t) and result in poor yields.
For best results soybean parent plants also are selected which inherently exhibit a propensity to flower during an overlapping time period at the location where grown. Such soybean plant parents may be either of the determinate type (i~e., flower over a period of approximately 20 to 25 days) or of the indeterminate type (i.e., flower over a period of approximately 35 to 50 days) so long as they flower simultane-ously at a period of time during the summer. In a particularly preferred embodiment the flowering period for the male fertile soybean plant parent commences before the flowering period for the male sterile soybean plant parent and ends after the flow-ering period for the male sterile plant parent. Accordingly, the male fertile parent may be from a longer flowering indeter-minate variety and the male sterile parent may be from a short-er flowering determinate variety. This will provide added 6~
insurance that pollen ~or the required cross-pollination will be available when the male sterile seed parent is ready to receive pollen.
In order to promote visitation by pollen-carrying bees (as discussed herPafter) the male sterile soybean plant parents can be selected for large blossom size to aid insect entry. Parent plants having flowers which are tightly cleistogamous are to be avoided sinc~ in such plants the flower keel tends not to open or the stigmas tend not to be exerted thereby making pollination difficult. Also, in order to promote visitation by pollen-carrying bees the flowers of both parents should be as attractive as possible to bees. Since, bees sometimes have a tendency to preferen--tially visit soybean flowers o~ a given color, it is preferred that the plants of each parent possess substan-tially the same flower coloration (e~., be all purple or all white). In a particularly preferred embodiment the flowers of each parent are purple in coloration since this coloration often is found to be preferred by ~he bees which are relied upon to accomplish pollen transfer.
In accordance with the concept of the pxesent inven~ion, water is applied via irrigation to the seeds which produce the male sterile and male fertile soybean plants fGllbwing planting as required to accomplish seed germination and normal plant growth up to at least the time o~ the onset of ~lower forma~ion on each o~ the two plant types. The customaxy soybean planting times commonly are employed. The quantity of water applied will be influenced by the ~requency and extent of nàtural rainfall (if any).
The manner in which the irrigation water is applied may be --~4-~7~7"5;
varied and commonly w~ll correspond to the irrigationtechnique that may be most conveniently implement~d at the particular location which normally experiences limited natural rainfall. As will be apparent to those skilled in agronomic technology, the particular irrigation technigue selected will also be influenced by the soil type encoun-tered and its inherent water-holding capabilities. Light soils will inherently re~uire lesser irrigation times and more frequent water applications. ~epresentative irrigation technigues that may be selectPd include (1) sprinkler systems whereby water is sprayed and impacts upon the planting area ~rom overhead through the air, (2) flooding systems whereby water confined by a levy or other means is caused to flow upon the sur~ace of the soil and to substan-tially completely engul~ the planting area, (3) furrow systems whereby a furrow is mechanically cut in the soil ad;acent to the locations where the soybean plant~ are grown and is filled with water, etc. Sprinkler systems commonly have the advantag~ of using less water. In northeastern Arkansas commonly a flooding system will be employed. In western Texas commonly a furrow system or a sprinkler system will be employed. Also commonly, the water is applied via irrigation ~or a period of approximately 0.1 to 15 days (or more) prior to the withholding of irrigation water (as de~cribed hereafter). The duration of the time in which water is applied by irrigation will primarily be in~luenced by the natural rainfall (i~ any), the okher weather condi-tions (e.q., heat and humidity) encountered, ~nd the a~ility of the soil to hold water once irrigat'on is commenced. In any event, water is always appl:Led as required Yia irriga--2~-~7~5 tion in sufficient quantities and at sufficient intervals to insure normal soybean plant growth up to at least the time when flowers are present on each of the parent plant types.
The application of water via irrigation promotes the normal vegetative growth of the soybean plants and flower formation. The nectar exuded by the resulting soybean flowers, when irrigation and/or natural rainfall is taking place, tends to be more dilute and is considerably less attrac~ive to bees than that formed in the subsequent step o~ the present process (described herea~ter) when irrigation water is withheld from the planting area.
The process o~ the present invention utilizes pollen-carrying bees to bring about the required cross-pollination of the parent soybean plants. At most growing areas honeybees are particularly e~fective in bringing about the desired cross-pollination. However, bees other than honeybee~ can alternatively be employed so long as they will reliably visit the soybean flowers at the appropriate time.
For instance, leaf-cutter bees (i.e., Meqachile rotundata) can be used. Also, naturally occurring bees other than ~oneybees and leaf-cutter bees (l.e., wild bees) advanta geously may supplement the le~el of sross-pollination. Bees appear to visit soybean plants primarily in search of nectar and to a lesser extent for pollen that erves as a protein sourae for the bees. As bees collect nectar, they concomit-antly serve to pick up and carry pollen from one soybean plant to another.
In a preferred embodiment of the process of the pre ent invention, one or moxe honeybee hives ars situatad in pollinating proximity to the location where the parent 7~
soybean plants are being grown in order to insure the ample presence of sufficient pollen vectors. Eor instance, in a particularly preferred embodiment, honeybee hives are provided in pollinating proximity to the location where the parent soy-bean plants are being grown at a rate of at least 2 hives per acre (e.g., 2 to 3 hives per acre) of the parent so~bean plants. When irrigation is accomplished by flooding, the hives may be situated on a small terrace above the water level. It ~urther is preferred that a route be provided in the planting area to provide ready ingress and egress for the beekeepers having the responsibility of servicing the beehives. Eor best results, it is recommended that the honeybee hives be positio-ned so that the honeybees are not required to travel more than approximately one-quarter of a mile to visit the parent soybean plants. This tends to improve the foraging efficiency.
Since pollen serves as a protein source required by bees and soybean plants tend not to produce pollen in pro-fuse quantities, it is preEerred that a supplemental protein source for the pollen-carrying bees be provided in addition to the pollen formed on the male parent soybean plants in order to more fully support the pollen requirements o~ the pollen-carry-ing bees. Such supplemental protein source for the enrichment of the bee diet may take various forms. For instance, plants kno~n to form pollen in relatively copious quantities te.g., sorghum, sudan, pearl millet, etc.) can be grown nearby.
Alternatively, a concentrated pollen sourcel such as pollen cakes available to beekeepers, can be placed in the vicini~y of or within the honeybee hives.
~2~7~7~
Insecticides must be used with care in the planting area since adult bees may be killed and sometimes bees will refuse to visit fields which have been sprayed with insecticides. Accordingly, i~ insecticides are used they should possess a low killing potential for bees, and preferably be applied during the night or some other time when any beehives in the area ar~ closed.
The overall process of the present invention provides a highly effective technique to bring about a high level of cross-pollination among the parent soybean plants.
~t an appropriate time when flowers are present on the parent soybean plants, irrigation water is withheld for a period of time during which no appreciable natural rainfall occurs in order to induce enhanced nectar flow within the flowers, which serves to render the flowers more attractive to bees. When irrigation water is withheld, the nectar flow within the soybean flowers increases substantially and the sugar component of the nectar becomes more concentrated and more aromatic. Such enhanced nectar flow is readily perceived by the bees that forage in the area and the bee~
are strongly attracted to the soybean flowers at a critical time in the life cycle of the soybean plants. Such increased bee visitation results in higher levels of the desired cros -pollination and seed set.
It is important that the period of time during which irrigation water is withheld not exceed that wh~ch can be well tolerated by the parent plants involved (i.e., not significantly impair th~ plant metabolism in a way which would interfere with the desired seed set and seed forma-tion). The duFation o~ the period in which lrrigation water :
is withheld at a time when no appreciable natural rainfall occurs will be influenced by the environmental conditions (~g~, temperature, humidity, wind velocity, etc.) and the water-holding ability o~ the soil. In a preferred embodi-ment, the irrigation water is withheld for a period of at least 8 days (e.q., 10 to 15 days).
At the conclusion of th period during which irrigation water is withheld, the paxent soybean plants may again be watered via irrigation to promote normal plant growth in order to insur~ the formation of the desired seeds that subse~u~ntly are harvested at the appropriate time in their maturity cycle. However, th~ proce~s steps optionally may be repeated at least one time (e.q., 1 or 2 more times3 during which irriyation water is applied, irrigation water is withheld, and additional cross-pollination by pollen-carrying bees is accomplished. Such repetition of the process step~ may be carried out to particular advantage when the parent soybean plants are selected that inherently ~lower over an extended period of time (e.g., when both of the soybean parent have indeterminate flowering character-istics). For instance, when both soybean plant parents have indeterminate flowering characteristics, irrigation water commonly is withheld for a total of 2 or 3 times (or more) during the flowering period Howeve1, when both soybean plant parents have determinate ~lowering characteristics, irrigation water commonly is withheld for a total of only 1 or 2 times during the flowering period.
The concept of the pxesent invention provides a highly efficient technique for aiding the accomplishment of the desired cross-pollination of male sterile soybean plants ~ ~9~;75 with the aid o~ bees. The enhanced level of seed set made posslble by the improved process of the present invention translates into greater and more reliable yields o~ the desi~ed seeds (e. q., seeds capable of growing male fertile Fl hybrid soybean plants or seeds capable o~ growing additional cytoplasmically male sterile soybean plants that are useful in the production o~ male fertile Fl hybrid soybean plants).
Although the invention has been described with pre~erred embodiments, it is to be understood that varia-tions and modi~ications may be resorted to as will be apparent to those ~killed in the art. Such variations and modifications are to be considered within the purview and scope of the claims appended hereto.
Soybeans (l.e., seeds of Glycine ~ax plants) are recognized to be an important crop in many parts of the world.
For instance, approximately 65 to 75 million acres of soybeans are planted annually in the United States which establi3hes this to be the largest seed crop presently grown in the United States. Various approaches to the production of hybrid soybeans are disclosed in United States Patent Nos. 3,903,645 and 4,077,157, and in my copending Canadian Serial No. 475,718.
Also, technical articles which discuss the existance of some degree of sterility in soybeans and the formation of hybrid soybean seeds are identified in my copending Canadian Serial No. 475,718.
It is an object of the present invention to provide an improved process for producing seeds capable of forming Fl hybrid soybean plants wherein pollen-carrying bees are employed to accomplish the required pollen transfer.
It is an object of the present invention to provide an improved process for maintaining male sterile soybean plants useful in the production of male fertile Fl hybrid soybean :
plants wherein pollen-carrying bees are employed to accomplish the required pollen transfer.
,, :~;
.
It is an object of the present invention to provide an improved process for producing seeds capable of forming Fl hybrid soybean plants wherein the required visitatlon between the parent plants by pollen-carrying bees is promoted on a highly effective basis.
It is another object of the present invention to provide an improved process ~or maintaining male sterile soybean plants useful in the production of male ~ertile F
hybrid soybean plants wherein the re~uired visitation between the parent plants by pollen carrying bees is promoted on a highly effective basis.
It i~ a further ob;eck of the present invention to provide an improved process for producing seeds capable of forming Fl hybrid ~oybean plants wherein the seed product is caused to set in increased yields.
These and other objects as well as the scope, nature, and utilization of the claimed invention will be apparent to those skilled in the art from the following detailed description and appended claims.
Summary of the_Invention It has been ~ound that an improved process for the efficient production of seeds capable o~ growing Fl hybrid Glycine max comprises:
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially uniform population of male sterile soybean plants in pollinating proximity to a ubstantially uni~orm population of male fertile soybean plants which when crossed with the male sterlle soybean plants enable the ~ormation o~ seeds on the male sterile ~oybean plants which are capable of growing male fertile Fl hybrid soybean plants, (b) applying water via irrigation to the substan-tially uni~orm populations of soybean plants of step (a) as required to promote normal ~ plant growth up to at least the time of the onset of ~lower formation within each of the populations, (c) withholdin~ irrigation water from the plants : of the substantially uni~o~m populations at a ~ime when flowers are present within each of the substantially uniform population~ ~or a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within the flowers which serves to render the ~lowers mora a~tractive : : ~ to bees, (~d? crossing the male sterile soybean plants and the male ~ertile soybean pla~ts with the aid :~ . of pollen-carrying bees which are attracted ;:
to the enhanced nectar ~low whereby seeds are ; .
:: ~ormed on the male sterile soyb~an plants, and (e) selectively recoveriny the seeds which have ~ormed on the substantially uniform popula-tion o~ male sterile soybean plants.
,:
~, It has been found that an improved process for the afficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile Fl hybrid Glycine max plants comprises:
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the su~mer a sub~tan-tially random population of male sterile soybean plants and male ~ertile soybean plant~ which when crossed with the male sterile soybean plants enable the ~ormation of seads on the male sterile soybean plants which are capable of growing male fertile F
hybrid soybean plants, (b) applying water via irxiyation to the substan-tially random population of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of ~lower formation, (c) withholding irrigation water from the plants of the substantially xandom population at a time when flowers are present for a period of time durin~ which no appreciable natural ' rainfall occurs so as to induce enhanced nectar flow wikhin the ~lowers which serves to render the flowers more attractive to bees, (d) pollinating the substantially random popula-tion of soybean plants with the aid o~
: pollen-carrying bees which are attracted to ~4-the enhanced nectar ~low whereby seedR are formed on the male sterile plants which are capable of growing male fertile Fl hybrid soybean plants and saeds are formed on the male fertile soybean plants as a result of self-pollination, and (e) recovering seeds which have ~ormed on the subs~antially random population of soybean plants.
It has been found that an improved process for maintaining male sterile ~ B~ ~3~ plants useful in the production of male fertile Fl hybrid soybean plant~ compri-ses:
(a) growing at a location whlch normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a ~ubstan-tially uniform population of cytoplasmically , male sterile soybean plants in pollinatlng i proximity to a substantially uniform popula-ion of male fertile main~ainer soybean plants which when cros~ed wlth the cytoplas-mically mal~ sterile soybean plants enable the forma~ion of seeds on the cytoplasmically male sterile plants which are capable of : growing addi~ional cytoplasmlcally male ~ .
sterile pl2nt5, ~; ~ (b~ applying wa~er via irriga~ion to the ~ubstan-tially uniform populations of soybean plants : - of step (a) as required to promot~ normal :~
_5_ .
plant growth up to at least the time of the onset of ~lower formation within each of the populations, (c) withholding irrigation water from the plants o~ the substantially uniform populations at a time when flowers are present within each of the substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so a~ to induce enhanced nectar flow within the flower~ which serves to render the flowers more attractive to bees, (d) crossing ~ha cytoplasmically male sterile soybean plants and the male fertile main-tainer soybean plants with the aid of pollen-carrying bees which are attracted to the enhanced nectar flow whereby seeds are formed on the male sterile soybean plants, and (e) selectively recovering the seed~ whioh have formed on the substantially uniform popula-tion of cytoplasmically male ~terlle soybean plants.
, ;~ Detailed Descripti n of the Inventi_n In accordance with the con~ept of the present in~ention it is essential tha~ the parent ~oybean plants be : gxown at a location which normally experiences limited natural rainfall during the summer months when soybean flower~ normally are ~ormed and cross-pollination is carried -6~
~2~ i75 out with the aid of pollen-carrying bees. Natural rainfall when soybean flowers are preaent can adversely impact upon the enhanced nectar flow within the soybean flowers made possible in the improved process of the present invention.
Accordingly, the location where the process of the present invention is carried out generally will be dif~erent than those areas where soybean plants customarily have been grown in the past. For instance, the bulk of those areas of the United States pr~viously devoted to the growing of soybeans for commercial crops and seeds will be unsuitable for hybrid seed production in accordance with the concept of the pre~ent invention. If the planting area experiences significant rainfall during the summer months when soybean ~lowers are present, this will introduce an element of unpredictability which will make it infeasible to attempt to implement the concept o~ the present invention. Such rain~all at an inappropriate time will destroy the highly e~fective enhanced pollen transfer among soybean plants as provided herein.
The location selected for growing the soybean plants may be one which experiences (1) limited natural rainfall throughout the entire year, or (2) li~ited natural rainfall during the summer months when soybean flowering capable of producing cross-pollination occurs ~i.e., soybean flowers are present on each parent~ and more plentiful xainfal1 at other times during the year.
In a preferred embodiment of the present invention the location selected to grow the soybean paxent plants will normally experience les~ than 4 inches o~ rainfall when soybean flowering occurs during the summer ~ e., the --7~
~25~7~7~
average natural rainfall for the past 10 years will be less than 4 inches when soybean flowering simultaneously occurs on each parent during the 3 summer months). In a particularly preferred embodiment of the present invention the location selected to grow the soybean parent plants will normally exper-ience less than 2 inches of rainfall (e.g., less than 1 inch of rain) when soybean flowering occurs during the summer (i.e., the average natural rainfall for the past 10 years will be less than 2 inches when soybean flowering simultaneously occurs on each parent during the 3 summer months).
In the United States the improved process of the present invention commonly will be carried out in relatively dry areas which are generally west of those where soybean plants customarily are grown. For instance, limited areas from within the Great Plains may be selected extending from South Dakota, eastern Wyoming, Nebraska, eastern Colorado, western Kansas, the Oklahoma panhandle, eastern New Mexico and western Texas which commonly are irrigated from the vast underground Ogallala Aquifer. See, "Plant Stress and Water Conservation Research Program: A Progress Report" published by the College of Ayricultural Sciences, Texas Tech University, Lubbock, Texas (1984) at Page 7 for a map which illustrates the location of the Ogallala Aquifer. The drier areas of Nebraska, Kansas, and western Texas are particularly suited for carrying out the improved process of the present invention.
Representative counties served by the Ogallala Aquifer where the process of the present invention can be ; - 8 -g~
carried out to particular advantage includa the South Dakota counties o~ Shannon, Bennett, Todd, Tripp, Gregory, and Gillette; the Wyoming counties of Converse~ Laramie, Platte, Goshen, and Niobrara; the N~braska counties of Dawes, Box Butte, Garden, Kimball, Morrill, Cheyenne, Sheridan, Banner, Scotts Bluff, Keith, Arthur, McPherson, Grant, Cherry, Hooker, Thomas, Deuel, Keya Paha, Perkins, Chase, Dundy, Hitchcock, Red Willow, Hayes, Frontier, Lincoln, Logan, Loup, Garfield, Holt, Rock, Valley, Greely, Sherman, Howard, Buf~alo, Hall, Gosper, Phelps, Kearney, Furnas, Harlan, Franklin, Webster, Adams, Wheeler, Antelope, and Boone; the Colorado counties oE Sedgwick, Phillips, Logan, Weld, ~organ, Washington, Yuma, Kit Carson, Cheyenne, Kiowa, Prowers, Baca, Las Animas, Bent, Otero, Crowley, and Lincoln; the Kansas counties of Cheyenne, Rawlins, Sherman, Thomas, Decatur, Sheridan, Norton, Phillips, Graham, Wallace, Logan, Greeley, Wichita, Scott, Ness, Hamilton, Kearney, Finney, Stanton, Grant, Ha~kell, Gray, Ford, Hodgman, Morton, Stevens, Seward, Mead, Clark, Kiowa, Comanche, Edwards, Pawnee, Pratt, Staf~ord, Barton, Rice, Reno, Kingman, McPhereson, Harvey, and Sedgwick; the Oklahoma counties of Cimarron, Texas, Beaver, Harpar, Woodward, Roger Mills, and Dewey; the New Mexico counties of Curry, Roosevelt, Chaves, L~a, and Quay; and the Taxas countie~ o~ Hartley, Dallam, Sherman, ~oore, Hansford, Hutchinson, Carson, Roberts, Hemphill, Gray, Wheeler, Deaf Smith, Randall, Armstrong, Donley, Parmer, Castro, Swisher, Briscoe, Bailey, Lamb, Hale, Floyd, Motley, Cochran, Hockley, Lubbock, Crosby, Dickens, Yoakum, Terry, Lynn, _g _ 7~7~
Garza, Gaines, Dawson, Andrews, Martin, Mitchell, Ector, Midland, and Glasscock.
The thirteen counties of northeastern Arkansas (i.e., Clay, Craighead, Cross, Crittenden, Greene, Independence, Jackson, Lawrence, Mississippi, Poinsett, Randolph, White and Woodruf~) are well suited for carrying out the process of the present invention since rainfall normally is limited at that location during the summer months.
Other illustrative areas in the United States where the process of the present invention conveniently can be practiced include the irrigated areas of Idaho, Oregon, Washington, California, etc.
Illustrative areas outside of the United States where the process of the present invention conveniently can be practiced inalude Argentina, Brazil, Chile, Mexico, Canada, Egypt, South Africa, Sudan, Turkey, U.S.S.R., India, People~' Republic o~ China, Australia, New Zealand, etc.
~ It should be understood, however, that the process :~ of the present invention can be carried out at any location in the northern or southern hemisphQres where the ~oil will support the growth o~ soybean plants, limited rainfall occurs during the summer, and irrigation water is available to promote normal plant growth~
It is preferred that the area selected be one in which.th~re is a relatively low pestlcide usage, honeybees customarily are kept and are available, and a wild be~
population is available.
The key parent soybean plants whi~h are grown in accordance with the concept of the present invention are male sterile soybean plants that serve as the seed parents and male fertile soybean plants that serve as the pollen parents.
The male sterile soybean plants are fully female fertile, but yield no viable pollen that produces unwanted self-pollination.
These male sterile soybean plants serve as the female parents following the required cross-pollination. Accordingly, all of the seed formed on the male sterile soybean plants following pollination will be capable of forming the desired soybean plants. The male sterilit~ of the male sterile soybean plants can be of varied causation. For instance, such plants may be cytoplasmically male sterile or genetically male sterile.
Alternatively, such plants may be rendered male sterile through the application of a chemical which destroys the ability of the plants to yield viable pollen (l.e., a gametocide). Represent-ative gametocides include FW45~ available from Rohm & Haas Co., I'D-1123 available from Pennwalt Corp., potassium 3,4-dichloro-5-isothiazolecarboxylate, 2,3-dichloroisobutyric acid and the water soluble salts thereof (e.g., sodium 2,3-dichloroisobuty-rate available from Rohm & Haas Co.), etc.
In accordance with a preferred embodiment of the present invention, the male sterile plants are cytoplasmically male sterile plants as described in my copending Canadian Serial No. 475,718. As described in such copending Applica-tion, three factors found to exist in available sources of Glycine max plants, when properly combined in a single plant by the intervention of man, provide an effective starting plant to accomplish the hybrid soybean production. Such factors (as described hereafter) L` '' t-have heretofore existed separately while dispersed in soybean plants from widely differing sources. The female fertile male sterile soybean plants possess (1) a Cms cytoplasm, ~2) a distinct pair of recessive rlrl genes in the cell nucleus, and (3) a distin~t pair o~ recessive r2r2 genes in the ce'l nucleus, which in combination render the plant incapable of producing viable pollen while otherwise carrying out the usual plant functions required to produce soybeans if viable pollen is provided ~rom another soybean plant.
Glycine max plants are self-destructing annuals which cannot be satisfactorily propagated by asexual means since if new plant~ are formed by cuttings, the new plants ars of a progressively smaller size. The preferred female fertile male sterile soybean plants can be successfully propagated (i.e., maintained) by sexual means as described hereafter. Also, these male sterile plants unlike soybean plants which rely exclusively on nuclear genes for ~terility -can be conveniently perpetuated or maintained without unwanted segregation with respect to sterility, as described herea~ter.
The atypical Cms cytoplasm of the preferred female fertile male sterile soybean plants can be derived through the female parent ~rom an appropriate cytvplasmic sour~e.
For instance, i~ has been found that the Cms cytoplasm r $uired in the female ~ertile ~ully male sterile soybean plants can b~ con~aniently derived from a Mandarin cytoplas-mic ~ource through the female parent. Many Northern ~oybean varieties are derived from this cytoplasmic source. Plants of this origin have been found inherently to po ~eR~ an ~ ~ 'S~`? ~
atypical cytoplasm of the type required to practice thepresent invention. Since this required ~actor is not contributed by nuclear genes and is not transmitted through the pollen, it can be considered cytoplasmic, non-Mendelian, extrachromosomal, uniparental, and maternal.
Representative commercially available soybean plants which are derived maternally from a Mandarin cytoplasmic source are ~delphia, Chippewa, Chippewa 64, Clark, Classic I, Classic II, Columbus, Cutler, Disoy, Elf, Ford, Grant, Harosoy, Harosoy 63, Hobbitt, Kent, Lincoln, Lindarin, Lindarin 63, Magna, Prize, Provar, Rampaga, RA 203, RA 402, RA 4~1, RAX 56, RAX 57, RAX 61, RAX 62, RAX 66, SB 27, Shelby, Traverse, Wayne~ Wirth, Williams, etc. A particu-larly good source for the re~uired Cms cytoplasm has been ~ound to be the El~ variety which was introduced during 1977 by AR-SEA-USD~, the Ohio Agric. Res. and Dev. Center, and the U. of Illinois Agric. Res. Station. In 1981 this variety was registered by the Crop Sci. Soc. of Am. as Reg.
No. 150.
It should be emphasized that when plants of the above-identified varieties are inspected for the possible absencQ o~ viable pollen production, that male aterile plants (either partially male sterile or completely male sterile~ wherein the sterility is attrikutable to the cytoplasm are not observed. It has been found that such sterility is not expressed even though the required atypical Cms cytopla m is presen~ because it is not in combination with the requirad recessive genss di cussed hereafter.
Instead such varieties can be shown to posses~ at least one pair o~ dominant RlRl or R2R2 genes (usually both pairs) -~$ ~,Y~ ~
which always leads to the expression of the usual viable pollen production even in the presence o~ the Cms cytoplasm.
The pair of recessive genes rlrl for male ster-ility present in the preferred female fertile fully male sterile plants employed in the process o~ the present invention can be derived through its male parent from a ~irst gene source which possesses such genes. Unlike the male ~terile plants, the ~irst gene source may possess a usua~ N cytoplasm which can be termed a "normal" or "neu~
tral" cytoplasm. When such cytoplasm is present, cytoplas-mically controlled male sterility is not ~xhibited regard-less o~ the nuclear genes which are present.
It has been found that the requisite pair of rlrl rQcessive genes ln tha cell nucleus of the ~emale fertile fully male sterile soybean plants conveniently can be derived ~hrough the male parent from a Dunfield germplasm base. Many Southern soybean variQties are derived from this germplasm base. Plants of this origin hav~ been found inherently to possess the required pair of recessive genes which has been designated rlrl. Representative commercially available soybean plants ~rom which the r1rl recessive genes may be derived are Bedford, Bethel, Centennial, Dare, Dyer, Forrest, Hill, Klrby, RA(d)41, RA 581, RA 603, RA 60~, RA
606, R~ 680, Tracy, Wabash, York, etc. A particularly good source for the rlrl recessive genes has been found to be the Bedford variety which was introduced during 1978 by FR-SEA-USDA, and the Tennessee and ULssissippi Agric. ~xpt.
Stations. This variety was re~istered by the Crop Sci. Soc.
of Am. as Reg. No. 118.
b ~
It further should be emphasized that when plants of the above-identified varieties having rlrl genes are inspected for the possible absence of viable pollen produc-tion, that male sterile plants (either partially male sterile or completely male sterile) wherein the sterility is attributable to the cytoplasm are not observed. It has been found that such sterility will not be expressed unless tha atypical Cms cytoplasm is present along with recessive genes r2r2. Instead such varieties can be shown to possess dominant R~R2 genes which restore male fertility.
The pair of recessive genes r2r2 for male steri-lity present in the preferred female ~ertile fully male sterile plants can be derived through its male parent from a second gene sourca which possesses such genes. Such r2r2 genes are present as a distinct gene pair apart from the rlr1 genes in the female fertile fully male sterile plants (i.e., they are present at di~ferent loci). Unlike the male sterile plants, the second gene source may possess a usual N
cytoplasm which can be termed a "normal" or "neutral"
cytopl~sm. As previously indicatad, when such cytoplasm is present oytoplasmically controlled male sterility is not exhibited regardless of the nuclear genes which are pres nt.
It has been found that the requisite pair of r2r2 recessive genes in the cell nucleus of the perferred female fextil~ ~ully male sterile soybean plants conveniently can be derived through the male parent from a Tokyo germplasm base. ~any Southern soybean varietie~ arQ derived from this germplasm basa. Plants of this origin have been ~ound inherently to possass the required pair of recessive genes which has been designated r2r2. Represantative commercially ~ 2~ 5 available soybean plants from which the r2r2 recessive genes may be derived are Bragg, Braxton~ Cobb, Govan, Hampton, Hampton 266, Hardee, Hutton, Jackson, Kirby, Majos, Ogden, RA 604, RA 701, RA 800, Volstate, Wright, etc. A particu-larly good source for the r2r2 recessive genes has been found in thQ Braxton variety which was introduced during 1979 by the USDA and various state Agric. Expt. Stations.
It additionally should be emphasized that when plants of the above identified varieties having r2r2 genes are inspected ~or the possible absence of viable pollen production, that male sterile plants (either partially male sterile or completely male sterile) wherein the sterility is attributable ta the cytoplasm are not observed. It has been ~ound that such sterility will not be expressed unless the atypical Cms cytoplasm is present along with recessive genes rlrl. In~tead such varieties can be shown to possess dominant RlR~ gene~ which restore male fertility.
The pre~erred female fertile fully male sterile plants can be maintained or perpetuated in spite of the male sterility by crossing with pollen ~rom a soybean plant which posse~ses an N oytoplasm and the two distinct pairs of recessive genes rlrl and r2r2. Such preferred maintainer plants are formed by the intervention of man through the comblnation of the required ~ackors and are not found in nature. The progeny sf this cross will again be ~emale fertile and fully male sterileO Also, should the perferred female ~rtile fully male sterile plants be crossed with pollen from a male fertility restorer (i. , having domin~nt RlRl genes and/or dominant R2R2 genes), then the progeny will be fully fertile Fl hybrid soybean plants. Suitabla male fertility restorer plants are readily available withoutmodification. For instance, any of the varieties heretofore named can perform this function. The only requirement is that plants which supply the pollen possess at least one pair o~ the required dominant fertility restoring genes.
The development of preferred f~male fertile fully male sterile soybean plants for use in the present inven-tion, as well as preferred maintainex plants for the same, can be exempli~iad through a plant breeding program employ-ing plants of the Elf, Bed~ord, and Braxton varieties. It should be understood, however, that the preferred embodiment of the present process can be equally well practiced through the utilization of soybean plants of other varieties provided the essential criteria set forth herein neverthe-less arè met. Initially plants of the Bedford variety (i.e., having an rlrl gene source) are crossed by hand with pollen from plants of the Braxton variety (i.e., having an r2r2 gen~ source). The progeny of thls cross are f-llly female fertile and male fertile and serve as a pollen source ~or plants of the Elf variaty (i.e., having a Cms cy~oplas-mic source). Such crossing to the Elf variety is again carried out hy hand under controlled conditions in the absence of Elf self-pollination. When the Fl seed which has fo~med on the Elf female parent is grown, it will be noted that all of the resulting plants are fully female fertile and male fertile. Each of these Fl plant~ is next se}f-pollinated through succeedin~ generations to form F2, F3, and F4 controlled populations which are inspected ~or the absence of viable polLen. It i5 observed that some plants are female fer~ile fully male fertile, som plants are female fertile partially male fertile (i.e., produceonly a limited quantity of viable pollen), and some plants are ~emale fertile fully male ~terile (i.e., produce no viable pollen).
The fact that none of the F1 plants were male sterile in this preferred embodiment aonfirms that the stsrility subsequently observed was not controlled solely by nuclear genes. The ratio~ in which the plants segregate in the F2, F3 and F4 generations with respect to male sterility confirm that the sterility is cytoplasmic in nature and the result o~ a more complex cytoplasmic/genetic system in which the genetic aspect is bifackorial (i.e., two distinct gene pairs at different loci are operative and are interacting with the cytoplasm). The ~ully male sterile plants possess the Cms cytoplasm and the rlrl and r2r2 genes. The par-tially male sterile plants possess the Cms cytoplasm and (l) Rlrl and r2r~ genes or (2) rlrl and R2r2 genes. The f`ully male fertile plants possess the Cms cytoplasm and RlRl genes and/or R2R~ genes. When the ~ully male sterile plants are crossed with pollen from the Elf, Bed~ord, and Braxton varieties, all F1 progeny are fully male fertile~
Accordingly, this indicates that no single parent variety (l.e., Elf, Bed~ord, or ~raxton) possesses sufficient genes to create male sterile Fl plantq.
Once the preferred mals st~rile plants are on hand, suitable maintainer plant~ (i.e~, those having an N
cytoplasm in combination with rlrl and r2r2 genes) can be devèloped by ~tandard plant bre~ding techniques lnvolving intercros~ing and introgre sion. For instance, tha required rlrl and r2r2 g~nes can be provided in existing soybean ~ ~,4~ $
varieties of agronomic importance having khe usual Ncytoplasm by intercrossing and possible backcrossing by hand with the pollen derived from female fertile partially male fertile plants obtained from the F2, F3 and F4 controlled populations obtained during or subse~uent to the development of the male sterile plants (described above). The Fl plants from this cross are grown and are self~pollinated to form F2 plants. Test cros~es of the fully male sterile plants pre~iously developed with pollen derived from the F2 plants are made and those plants are identified and preserved which are capabls of yielding fully male sterile Fl progeny. Such plants possess the full complement of recessive rlrl and r2r2 genes. Once identified such preferred homozygous maintainer plants can ~Q perpetuated by self-pollination.
When producing seeds capable of growing male fertile Fl hybrid soybean plants in accordanc~ with one embodiment of the process of the present invention, the required male sterile soybean plants are grown at an appropriate location as a substantially uniform population in pGllinating proximity to a substantially uniform popula-tion of male fertile soybean plants. In the context of the present invent~on "pollinating proximity" specifies tha~ the two types o~ parent plants are sufficiently near that pollen can be tran~fexred by pollen-carrying bees without loss of its viability. The male ~ertile soybean plants conveniently can be a pure line variety. For instance, the two types of plants can be grown adjacent to ~ach other as alternating strips. In a preferred embodiment approximately 2, 4, or 6 rows o~ the male sterile soybean plants form a substantially uni~orm population and alternate with a substantlally uniform population of approximately 2 rows of the male fertile soybean plants. Following pollen transfer from the male ~ertile soybean plants to the male sterile plants (as described hereafter3, seeds are formed on the male sterile soybean plants. The male fertile soybean plants commonly are self-pollinated and seeds also form on them. At harvest time the seeds are selectively recovered from each of the substantially uniform plant populations. Accordingly, the seeds which are recovered from the male sterile soybean plants are a substantially homogeneous assemblage of saeds which upon growth yield male fertile Fl hybrid soybean plant~.
In accordance with another embodimenk of the process of the present invention, a substantially uniform binary seed blend is formed containing a substantial proportion (e.q., at least one-half by number) of seeds capable of growing male fertile Fl hybrid soybean plants.
Such blend can be formed by growing at an appropriate location a substantially random population of male sterile soybean plants together with the male fertile soybean plants. For instance, approximately 75 to 95 percent (e.a., approximately 90 percent) of the plants in the random population can be male sterile plants and approximately 5 to 25 percent (e.g~, approximately 10 percent~ of the plants in the random population can be the male fertilQ soybean plants. Following pollen trans~er the seeds formed on the mal~ stsrile soybean plants are capable of forming the male fertil~ Fl hybrid soybean plants, and the seede formed on the restorer soybean plants are the result of self-pollina-tion. The resulting seeds formed on the subs~antlally -20~
76~
random population of soybean plants next are harvested in bulk and can be planted in bulk by the grower.
The level of cross-pollination occurring in the random population of plants (discussed hereafter) can be visually observed by inspecting the resulting seeds or the plants produced when the resulting seeds are grown if one incorporates an appropriate genetic marker system into the parent plants which gives one appearance upon cro~s-pollina-tion and another appearance upon self-pollination. The genetic marker can take the form o~ a recessive gene which expresses itself upon self-pollination, but which is dominated by another gene giving a different appearance when cross-pollination takes place. Under such circum-stances the male ~ertile plants could be homozygous rece~-sive for such trait and the male sterile plants homozygous dominant for such trait. For instance, the genetic marker can be a distinctive pubescence color (e.q., gray pubescence vs. tawny pubescence~, ~lower color (e.q., white flowers vs.
purple flowers~, seed pod color (e.q., tan vs. brown pods3, hilum appearance (~, yellow vs. black hilum or bu~f vs.
black hilum), etc.
Alternatively, cytoplasmically male sterile soybean plants use~ul in the production of male fertile F
hydrid soybean plants can be maintained, perpetuated/ and multiplied by planting a substantially uniform population of th~ same in pollinating proxim~ty to a substantially uniform population o~ the maintainer soybean plants which when crossed with the male sterile ~oybean plants enable the formation o~ seeds on the cytoplasmically male st~rile ~oybean plants which are capabl~ of growing additional 7 ~
cytoplasmically male sterile plants. For instance, the twotypes of plants can be grown adjacent to each other as alternating strips as described earlier with respect to the production of male ~ertile Fl hybrid seed. Following pollen transfer (as described hereafter) from the maintainar soybean plantq to the male sterile soybean plants seeds ~re formed on the male sterile ~oybean plants. The maintainer plants are self-pollinated and seeds also ~orm on them. At harvest time the seeds are selectively harvested from each of the substantially uniform plant populations.
Accordingly, the seeds which are recovered from the male sterile soybean plants are a substantially homogeneous assQmblage of seeds which upon growth yield cytoplasmically male sterile soybean plants. The seeds which are selec-tivaly recovered ~rom the maintainer plant~ can be planted to produce additional maintainer plants or sold as a commercial soybean product.
Since the photosensitivity of soybean plants tends to vary among soybean varieties, it is important for best results that the parent soybean plants (i.e., the male sterile soybean plants and the male fertile soybean plant~) each possess a day length sensitivity ~i-e-, a photoperiod response) which generally corresponds to that of the location (i.e., the latitude or di~tance ~rom the equator) where the soybean plants are grown when carrying out the proces~ o~ the present invention as well as to the area wh~re the seed product i5 ultimately to be grown. Fox instance, the parent plant~ and the ultimate seed product preferably should posses~ a photo~ensitivity within plus or minus one maturity group unit o~ the locations where grown.
Additionally, for optimum results the locations where grown should correspond exactly -to the maturity groups of the plants involved. See, Chapter 6 by Edgar E. Hartwig of "Soybeans:
Improvement, Production, and Uses", American Society of Agronomy, Inc., Pages 189 to 190 (1973), for a discussion of soybean maturity group units and their significance. For in-stance, if a soybean variety which grows well at a southern latitude is grown at a northern latitude, the longer days may cause the soybean plants to grow excessively tall and to tend to lodge. Alternatively, if a soybean variety which grows well at a northern latitude is grown at a southern latitude, the shorter days may cause limited plant growth (i.e., heigh-t) and result in poor yields.
For best results soybean parent plants also are selected which inherently exhibit a propensity to flower during an overlapping time period at the location where grown. Such soybean plant parents may be either of the determinate type (i~e., flower over a period of approximately 20 to 25 days) or of the indeterminate type (i.e., flower over a period of approximately 35 to 50 days) so long as they flower simultane-ously at a period of time during the summer. In a particularly preferred embodiment the flowering period for the male fertile soybean plant parent commences before the flowering period for the male sterile soybean plant parent and ends after the flow-ering period for the male sterile plant parent. Accordingly, the male fertile parent may be from a longer flowering indeter-minate variety and the male sterile parent may be from a short-er flowering determinate variety. This will provide added 6~
insurance that pollen ~or the required cross-pollination will be available when the male sterile seed parent is ready to receive pollen.
In order to promote visitation by pollen-carrying bees (as discussed herPafter) the male sterile soybean plant parents can be selected for large blossom size to aid insect entry. Parent plants having flowers which are tightly cleistogamous are to be avoided sinc~ in such plants the flower keel tends not to open or the stigmas tend not to be exerted thereby making pollination difficult. Also, in order to promote visitation by pollen-carrying bees the flowers of both parents should be as attractive as possible to bees. Since, bees sometimes have a tendency to preferen--tially visit soybean flowers o~ a given color, it is preferred that the plants of each parent possess substan-tially the same flower coloration (e~., be all purple or all white). In a particularly preferred embodiment the flowers of each parent are purple in coloration since this coloration often is found to be preferred by ~he bees which are relied upon to accomplish pollen transfer.
In accordance with the concept of the pxesent inven~ion, water is applied via irrigation to the seeds which produce the male sterile and male fertile soybean plants fGllbwing planting as required to accomplish seed germination and normal plant growth up to at least the time o~ the onset of ~lower forma~ion on each o~ the two plant types. The customaxy soybean planting times commonly are employed. The quantity of water applied will be influenced by the ~requency and extent of nàtural rainfall (if any).
The manner in which the irrigation water is applied may be --~4-~7~7"5;
varied and commonly w~ll correspond to the irrigationtechnique that may be most conveniently implement~d at the particular location which normally experiences limited natural rainfall. As will be apparent to those skilled in agronomic technology, the particular irrigation technigue selected will also be influenced by the soil type encoun-tered and its inherent water-holding capabilities. Light soils will inherently re~uire lesser irrigation times and more frequent water applications. ~epresentative irrigation technigues that may be selectPd include (1) sprinkler systems whereby water is sprayed and impacts upon the planting area ~rom overhead through the air, (2) flooding systems whereby water confined by a levy or other means is caused to flow upon the sur~ace of the soil and to substan-tially completely engul~ the planting area, (3) furrow systems whereby a furrow is mechanically cut in the soil ad;acent to the locations where the soybean plant~ are grown and is filled with water, etc. Sprinkler systems commonly have the advantag~ of using less water. In northeastern Arkansas commonly a flooding system will be employed. In western Texas commonly a furrow system or a sprinkler system will be employed. Also commonly, the water is applied via irrigation ~or a period of approximately 0.1 to 15 days (or more) prior to the withholding of irrigation water (as de~cribed hereafter). The duration of the time in which water is applied by irrigation will primarily be in~luenced by the natural rainfall (i~ any), the okher weather condi-tions (e.q., heat and humidity) encountered, ~nd the a~ility of the soil to hold water once irrigat'on is commenced. In any event, water is always appl:Led as required Yia irriga--2~-~7~5 tion in sufficient quantities and at sufficient intervals to insure normal soybean plant growth up to at least the time when flowers are present on each of the parent plant types.
The application of water via irrigation promotes the normal vegetative growth of the soybean plants and flower formation. The nectar exuded by the resulting soybean flowers, when irrigation and/or natural rainfall is taking place, tends to be more dilute and is considerably less attrac~ive to bees than that formed in the subsequent step o~ the present process (described herea~ter) when irrigation water is withheld from the planting area.
The process o~ the present invention utilizes pollen-carrying bees to bring about the required cross-pollination of the parent soybean plants. At most growing areas honeybees are particularly e~fective in bringing about the desired cross-pollination. However, bees other than honeybee~ can alternatively be employed so long as they will reliably visit the soybean flowers at the appropriate time.
For instance, leaf-cutter bees (i.e., Meqachile rotundata) can be used. Also, naturally occurring bees other than ~oneybees and leaf-cutter bees (l.e., wild bees) advanta geously may supplement the le~el of sross-pollination. Bees appear to visit soybean plants primarily in search of nectar and to a lesser extent for pollen that erves as a protein sourae for the bees. As bees collect nectar, they concomit-antly serve to pick up and carry pollen from one soybean plant to another.
In a preferred embodiment of the process of the pre ent invention, one or moxe honeybee hives ars situatad in pollinating proximity to the location where the parent 7~
soybean plants are being grown in order to insure the ample presence of sufficient pollen vectors. Eor instance, in a particularly preferred embodiment, honeybee hives are provided in pollinating proximity to the location where the parent soy-bean plants are being grown at a rate of at least 2 hives per acre (e.g., 2 to 3 hives per acre) of the parent so~bean plants. When irrigation is accomplished by flooding, the hives may be situated on a small terrace above the water level. It ~urther is preferred that a route be provided in the planting area to provide ready ingress and egress for the beekeepers having the responsibility of servicing the beehives. Eor best results, it is recommended that the honeybee hives be positio-ned so that the honeybees are not required to travel more than approximately one-quarter of a mile to visit the parent soybean plants. This tends to improve the foraging efficiency.
Since pollen serves as a protein source required by bees and soybean plants tend not to produce pollen in pro-fuse quantities, it is preEerred that a supplemental protein source for the pollen-carrying bees be provided in addition to the pollen formed on the male parent soybean plants in order to more fully support the pollen requirements o~ the pollen-carry-ing bees. Such supplemental protein source for the enrichment of the bee diet may take various forms. For instance, plants kno~n to form pollen in relatively copious quantities te.g., sorghum, sudan, pearl millet, etc.) can be grown nearby.
Alternatively, a concentrated pollen sourcel such as pollen cakes available to beekeepers, can be placed in the vicini~y of or within the honeybee hives.
~2~7~7~
Insecticides must be used with care in the planting area since adult bees may be killed and sometimes bees will refuse to visit fields which have been sprayed with insecticides. Accordingly, i~ insecticides are used they should possess a low killing potential for bees, and preferably be applied during the night or some other time when any beehives in the area ar~ closed.
The overall process of the present invention provides a highly effective technique to bring about a high level of cross-pollination among the parent soybean plants.
~t an appropriate time when flowers are present on the parent soybean plants, irrigation water is withheld for a period of time during which no appreciable natural rainfall occurs in order to induce enhanced nectar flow within the flowers, which serves to render the flowers more attractive to bees. When irrigation water is withheld, the nectar flow within the soybean flowers increases substantially and the sugar component of the nectar becomes more concentrated and more aromatic. Such enhanced nectar flow is readily perceived by the bees that forage in the area and the bee~
are strongly attracted to the soybean flowers at a critical time in the life cycle of the soybean plants. Such increased bee visitation results in higher levels of the desired cros -pollination and seed set.
It is important that the period of time during which irrigation water is withheld not exceed that wh~ch can be well tolerated by the parent plants involved (i.e., not significantly impair th~ plant metabolism in a way which would interfere with the desired seed set and seed forma-tion). The duFation o~ the period in which lrrigation water :
is withheld at a time when no appreciable natural rainfall occurs will be influenced by the environmental conditions (~g~, temperature, humidity, wind velocity, etc.) and the water-holding ability o~ the soil. In a preferred embodi-ment, the irrigation water is withheld for a period of at least 8 days (e.q., 10 to 15 days).
At the conclusion of th period during which irrigation water is withheld, the paxent soybean plants may again be watered via irrigation to promote normal plant growth in order to insur~ the formation of the desired seeds that subse~u~ntly are harvested at the appropriate time in their maturity cycle. However, th~ proce~s steps optionally may be repeated at least one time (e.q., 1 or 2 more times3 during which irriyation water is applied, irrigation water is withheld, and additional cross-pollination by pollen-carrying bees is accomplished. Such repetition of the process step~ may be carried out to particular advantage when the parent soybean plants are selected that inherently ~lower over an extended period of time (e.g., when both of the soybean parent have indeterminate flowering character-istics). For instance, when both soybean plant parents have indeterminate flowering characteristics, irrigation water commonly is withheld for a total of 2 or 3 times (or more) during the flowering period Howeve1, when both soybean plant parents have determinate ~lowering characteristics, irrigation water commonly is withheld for a total of only 1 or 2 times during the flowering period.
The concept of the pxesent invention provides a highly efficient technique for aiding the accomplishment of the desired cross-pollination of male sterile soybean plants ~ ~9~;75 with the aid o~ bees. The enhanced level of seed set made posslble by the improved process of the present invention translates into greater and more reliable yields o~ the desi~ed seeds (e. q., seeds capable of growing male fertile Fl hybrid soybean plants or seeds capable o~ growing additional cytoplasmically male sterile soybean plants that are useful in the production o~ male fertile Fl hybrid soybean plants).
Although the invention has been described with pre~erred embodiments, it is to be understood that varia-tions and modi~ications may be resorted to as will be apparent to those ~killed in the art. Such variations and modifications are to be considered within the purview and scope of the claims appended hereto.
Claims (112)
1. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants comprising:
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially uniform population of male sterile soybean plants in pollinating proximity to a substantially uniform population of male fertile soybean plants which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile soybean plants which are capable of growing male fertile F1 hybrid soybean plants, (b) applying water via irrigation to said substantially uniform populations of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation within each of said populations, (c) withholding irrigation water from said plants of said substantially uniform populations at a time when flowers are present within each of said substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said male sterile soybean plants and said male fertile soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) selectively recovering the seeds which have formed on said substantially uniform popula-tion of male sterile soybean plants.
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially uniform population of male sterile soybean plants in pollinating proximity to a substantially uniform population of male fertile soybean plants which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile soybean plants which are capable of growing male fertile F1 hybrid soybean plants, (b) applying water via irrigation to said substantially uniform populations of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation within each of said populations, (c) withholding irrigation water from said plants of said substantially uniform populations at a time when flowers are present within each of said substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said male sterile soybean plants and said male fertile soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) selectively recovering the seeds which have formed on said substantially uniform popula-tion of male sterile soybean plants.
2. An improved process for the efficient produc-tion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said male sterile soybean plants of step (a) are cytoplasmically male sterile.
3. An improved process for the efficient produc-tion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said male sterile soybean plants of step (a) are genetically male sterile.
4. An improved process for the efficient produc-tion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said male sterile soybean plants of step (a) are rendered male sterile through the application of a gametocide.
5. An improved process for the efficient produc-tion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein the flower-ing period at said location for said male fertile soybean plants of step (a) commences before the flowering period for said male sterile soybean plants of step (a) and ends after the flowering period for said male sterile plants.
6. An improved process for the efficient produc-tion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said substantially uniform populations of male sterile soybean plants and male fertile soybean plants are grown in alter-nating strips.
7. An improved process for the efficient produc-tion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 which includes the additional step of selectively recovering seeds formed on said substantially uniform population of male fertile soybean plants grown in step (a).
8. An improved process for the efficient produc-tion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said male fertile soybean plants grown in step (a) are a pure line variety.
9. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said limited natural rain-fall when soybean flowering occurs during the summer is normal-ly less than 4 inches.
10. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said limited natural rain-fall when soybean flowering occurs during the summer is normal-ly less than 2 inches.
11. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess a day length sensitivity which generally corresponds to that of said location of step (a) and the area where the seeds capable of growing said male sterile F1 hybrid plants are to be grown.
12. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess substantially the same flower coloration.
13. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess purple flowers.
14. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein water is applied by irrigation during step (b) for a period of approximately 0.1 to 15 days prior to the withholding of irrigation water in step (c).
15. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein water is withheld in step (c) for a period of at least 8 days.
16. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein water is withheld in step (c) for a period of approximately 10 to 15 days.
17. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein said pollen-carrying bees of step (d) are primarily honeybees.
18. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 17 wherein honeybee hives are provided in pollinating proximity to said location of step (a) at a rate of at least 2 hives per acre of said substantially uniform popula-tions of soybean plants.
19. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein following step (d), steps (b), (c) and (d) are successively repeated at least one time prior to step (e).
20. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 1 wherein a supplemental pollen source for said pollen-carrying bees is provided in addition to the pollen formed on said male fertile soybean plants of step (a) in order to provide ample pollen to support said pollen-carrying bees.
21. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants comprising;
(a) growing at a location which normally experiences limited natural rainfall when soybean flowering occurs during the summer a substantially uniform population of male sterile soybean plants wherein said male sterility is attributable to the combination of an atypical Cms cytoplasm and two distinct pairs of recessive genes r1r1 and r2r2 in pollinat-ing proximity to a substantially uniform population of male fertile soybean plants which possess at least one pair of dominant genes selected from the group consisting of R1R1 and R2R2 and which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile soybean plants which are capable of growing male fertile F1 hybrid soybean plants, (b) applying water via irrigation to said substantially uniform populations of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation within each of said populations, (c) withholding irrigation water from said plants of said substantially uniform populations at a time when flowers are present within each of said substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said male sterile soybean plants and said male fertile soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) selectively recovering the seeds which have formed on said substantially uniform popula-tion of male sterile soybean plants.
(a) growing at a location which normally experiences limited natural rainfall when soybean flowering occurs during the summer a substantially uniform population of male sterile soybean plants wherein said male sterility is attributable to the combination of an atypical Cms cytoplasm and two distinct pairs of recessive genes r1r1 and r2r2 in pollinat-ing proximity to a substantially uniform population of male fertile soybean plants which possess at least one pair of dominant genes selected from the group consisting of R1R1 and R2R2 and which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile soybean plants which are capable of growing male fertile F1 hybrid soybean plants, (b) applying water via irrigation to said substantially uniform populations of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation within each of said populations, (c) withholding irrigation water from said plants of said substantially uniform populations at a time when flowers are present within each of said substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said male sterile soybean plants and said male fertile soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) selectively recovering the seeds which have formed on said substantially uniform popula-tion of male sterile soybean plants.
22. A process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein with respect to said male sterile soybean plants of step (a) said atypical Cms cytoplasm was derived through its female parent from an appropriate cytoplasmic source, and in which said recessive genes r1r1 were derived through its male parent from a first gene source which possessed said r1r1 genes, and in which said recessive genes r2r2 additionally were derived through its male parent from a second gene source which possessed said r2r2 genes.
23. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 22 wherein with respect to said male sterile soybean plants of step (a) said atypical Cms cytoplasm was derived through its female parent from a Mandarin cytoplasmic source, and in which said recessive genes r1r1 were derived through its male parent from a Dunfield germplasm base and in which said recessive genes r2r2 additionally were derived through its male parent from a Tokyo germplasm base.
24. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 23 wherein with respect to said male sterile soybean plants of step (a) said atypical Cms cytoplasm was derived through its female parent from the Elf variety, and in which said recessive genes r1r1 were derived through its male parent from the Bedford variety, and in which said recessive genes r2r2 additionally were derived through its male parent from the Braxton variety.
25. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein the flowering period at said location for said male fertile soybean plants of step (a) commences before the flowering period for said male sterile soybean plants of step (a) and ends after the flowering period for said male sterile plants.
26. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein said substantially uniform populations of male sterile soybean plants and male fertile soybean plants are grown in alterna-ting strips.
27. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 which includes the additional step of selectively recovering seeds formed on said substantially uniform population of male fertile soybean plants grown in step (a).
28. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein said male fertile soybean plants grown in step (a) are a pure line variety.
29. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein said limited natural rain fall when soybean flowering occurs during the summer is normally less than 4 inches.
30. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein said limited natural rainfall when soybean flowering occurs during the summer is normally less than 2 inches.
31. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess a day length sensitivity which generally corresponds to that of said location of step (a) and the area where the seeds capable of growing said male sterile F1 hybrid plants are to be grown.
32. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess substantially the same flower coloration.
33. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess purple flowers.
34. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein water is applied by irrigation during step (b) for a period of approximately 0.1 to 15 days prior to the withholding of irrigation water in step (c).
35. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein water is withheld in step (c) for a period of at least 8 days.
36. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein water is withheld in step (c) for a period of approximately 10 to 15 days.
37. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein said pollen-carrying bees of step (d) are primarily honeybees.
38. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 37 wherein honeybee hives are provided in pollinating proximity to said location of step (a) at a rate of at least 2 hives per acre of said substantially uniform populations of soybean plants.
39. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein following step (d), steps (b), (c), and (d) are successively repeated at least one time prior to step (e).
40. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 21 wherein a supplemental pollen source for said pollen-carrying bees is provided in addition to the pollen formed on said male fertile soybean plants of step (a) in order to provide ample pollen to support said pollen-carrying bees.
41. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants comprising:
(a) growing at a location which normally experiences limited natural rainfall when soybean flowering occurs during the summer a substantially random popu-lation of male sterile soybean plants and male fer-tile soybean plants which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile soybean plants which are capable of growing male fertile F1 hybrid soybean plants, (b) applying water via irrigation to said substantially random population of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation, (c) withholding irrigation water from said plants of said substantially random population at a time when flowers are present for a period of timeduring which no appreciable natural rainfalloccurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) pollinating said substantially random population of soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile plants which are capable of growing male fertile F1 hybrid soybean plants and seeds are formed on said male fertile soybean plants as a result of self-pollination, and (e) recovering seeds which have formed on said substantially random population of soybean plants.
(a) growing at a location which normally experiences limited natural rainfall when soybean flowering occurs during the summer a substantially random popu-lation of male sterile soybean plants and male fer-tile soybean plants which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile soybean plants which are capable of growing male fertile F1 hybrid soybean plants, (b) applying water via irrigation to said substantially random population of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation, (c) withholding irrigation water from said plants of said substantially random population at a time when flowers are present for a period of timeduring which no appreciable natural rainfalloccurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) pollinating said substantially random population of soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile plants which are capable of growing male fertile F1 hybrid soybean plants and seeds are formed on said male fertile soybean plants as a result of self-pollination, and (e) recovering seeds which have formed on said substantially random population of soybean plants.
42. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein said male sterile soybean plants of step (a) are cytoplasmically male sterile.
43. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein said male sterile soybean plants of step (a) are genetically male sterile.
44. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein the flowering period at said location for said male fertile soybean plants of step (a) commences before the flowering period for said male sterile soybean plants of step (a) and ends after the flowering period for said male sterile plants.
45. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein said male fertile soybean plants grown in step (a) are a pure line variety.
46. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein said limited natural rain fall when soybean flowering occurs during the summer is normally less than 4 inches.
47. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein said limited natural rain fall when soybean flowering occurs during the summer is normally less than 2 inches.
48. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess a day length sensitivity which generally corresponds to that of said location of step (a) and the area where the seeds capable of growing said male sterile F1 hybrid plants are to be grown.
49. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess substantially the same flower coloration.
50. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess purple flowers.
51. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein water is applied by irrigation during step (b) for a period of approximately 0.1 to 15 days prior to the withholding of irrigation water in step (c).
52. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein water is withheld in step (c) for a period of at least 8 days.
53. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein water is withheld in step (c) for a period of approximately 10 to 15 days.
54. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein said pollen-carrying bees of step (d) are primarily honeybees.
55. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 54 wherein honeybee hives are provi-ded in pollinating proximity to said location of step (a) at a rate of at least 2 hives per acre of said substantially random population of soybean plants.
56. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein following step (d), steps (b), (c) and (d) are successively repeated at least one time prior to step (e).
57. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 41 wherein a supplemental pollen source for said pollen-carrying bees is provided in addition to the pollen formed on said male fertile soybean plants of step (a) in order to provide ample pollen to support said pollen-carrying bees.
58. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants comprising:
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially random population of (i) male sterile soybean plants wherein said male sterility is attributable to the combination of an atypical Cms cytoplasm and two distinct pairs of recessive genes r1r1 and r2r2, and (ii) male fertile soybean plants which possess at least one pair of dominant genes selected from the group consisting of R1R1 and R2R2 and which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile soybean plants which are capable of growing male fertile F1 hybrid soybean plants, (b) applying water via irrigation to said substantially random population of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation, (c) withholding irrigation water from said plants of said substantially random population at a time when flowers are present for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said male sterile soybean plants and said male fertile soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) recovering seeds which have formed on said substantially random population of soybean plants.
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially random population of (i) male sterile soybean plants wherein said male sterility is attributable to the combination of an atypical Cms cytoplasm and two distinct pairs of recessive genes r1r1 and r2r2, and (ii) male fertile soybean plants which possess at least one pair of dominant genes selected from the group consisting of R1R1 and R2R2 and which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile soybean plants which are capable of growing male fertile F1 hybrid soybean plants, (b) applying water via irrigation to said substantially random population of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation, (c) withholding irrigation water from said plants of said substantially random population at a time when flowers are present for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said male sterile soybean plants and said male fertile soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) recovering seeds which have formed on said substantially random population of soybean plants.
59. An improved process for the efficient production of a binary seed blend containing a substantial production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein with respect to said male sterile soybean plants of step (a) said atypical Cms cytoplasm was derived through its female parent from an appropriate cytoplasmic source, and in which said recessive genes r1r1 were derived through its male parent from a first gene source which possessed said r1r1 genes, and in which said recessive genes r2r2 additionally were derived through its male parent from a second gene source which possessed said r2r2 genes.
60. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 59 wherein with respect to said male sterile soybean plants of step (a) said atypical Cms cytoplasm was derived through its female parent from a Mandarin cytoplasmic source, and in which said recessive genes r1r1 were derived through its male parent from a Dunfield germplasm base and in which said recessive genes r2r2 additionally were derived through its male parent from a Tokyo germplasm base.
61. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 60 wherein with respect to said male sterile soybean plants of step (a) said atypical Cms cytoplasm was derived through its female parent from the Elf variety, and in which said recessive genes r1r1 were derived through its male parent from the Bedford variety, and in which said recessive genes r2r2 additionally were derived through its male parent from the Braxton variety.
62. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein the flowering period at said location for said male fertile soybean plants of step (a) commences before the flowering period for said male sterile soybean plants of step (a) and ends after the flowering period for said male sterile plants.
63. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein said male fertile soybean plants grown in step (a) are a pure line variety.
64. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein said limited natural rainfall when soybean flowering occurs during the summer is normally less than 4 inches.
65. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein said limited natural rainfall when soybean flowering occurs during the summer is normally less than 2 inches.
66. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess a day length sensitivity which generally corresponds to that of said location of step (a) and the area where the seeds capable of growing said male sterile F1 hybrid plants are to be grown.
67. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess substantially the same flower coloration.
68. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein said male sterile soybean plants and said male fertile soybean plants of step (a) each possess purple flowers.
69. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein water is applied by irrigation during step (b) for a period of approximately 0.1 to 15 days prior to the withholding of irrigation water in step (c).
70. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein water is withheld in step (c) for a period of at least 8 days.
71. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein water is withheld in step (c) for a period of approximately 10 to 15 days.
72. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein said pollen-carrying bees of step (d) are primarily honeybees.
73. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 72 wherein honeybees hives are provided in pollinating proximity to said location of step (a) at a rate of at least 2 hives per acre of said substantially random population of soybean plants.
74. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein following step (d), steps (b), (c), and (d) are successively repeated at least one time prior to step (e).
75. An improved process for the efficient production of a binary seed blend containing a substantial proportion of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 58 wherein a supplemental pollen source for said pollen-carrying bees is provided in addition to the pollen formed on said male fer-tile soybean plants of step (a) in order to provide ample pollen to support said pollen-carrying bees.
76. An improved process for maintaining male sterile Glycine max plants useful in the production of of male fertile F1 hybrid soybean plants comprising:
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially uniform population of cytoplasmically male sterile soybean plants in pollinating proximity to a substantially uniform popula-tion of male fertile maintainer soybean plants which when crossed with said cytoplas-mically male sterile soybean plants enable the formation of seeds on said cytoplas-mically male sterile plants which are capable of growing additional cytoplasmically male sterile plants, (b) applying water via irrigation to said substantially uniform populations of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation within each of said populations, (c) withholding irrigation water from said plants of said substantially uniform populations at a time when flowers are present within each of said substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said cytoplasmically male sterile soybean plants and said male fertile main-tainer soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) selectively recovering the seeds which have formed on said substantially uniform popula-tion of cytoplasmically male sterile soybean plants.
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially uniform population of cytoplasmically male sterile soybean plants in pollinating proximity to a substantially uniform popula-tion of male fertile maintainer soybean plants which when crossed with said cytoplas-mically male sterile soybean plants enable the formation of seeds on said cytoplas-mically male sterile plants which are capable of growing additional cytoplasmically male sterile plants, (b) applying water via irrigation to said substantially uniform populations of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation within each of said populations, (c) withholding irrigation water from said plants of said substantially uniform populations at a time when flowers are present within each of said substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said cytoplasmically male sterile soybean plants and said male fertile main-tainer soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) selectively recovering the seeds which have formed on said substantially uniform popula-tion of cytoplasmically male sterile soybean plants.
77. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 76 wherein the flowering period at said location for said male fertile soybean plants of step (a) commences before the flowering period for said male sterile soybean plants of step (a) and ends after the flowering period for said male sterile plants.
78. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein said substantially uniform populations of cytoplas-mically male sterile soybean plants and male fertile soybean plants are grown in alternating strips.
79. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 which includes the additional step of selectively recovering seeds formed on said substantially uniform population of male fertile maintainer soybean plants grown in step (a).
80. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein said male fertile maintainer soybean plants grown in step (a) are a pure line variety.
81. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein said limited natural rainfall when soybean flowering occurs during the summer is normally less than 4 inches.
82. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein said limited natural rainfall when soybean flowering occurs during the summer is normally less than 2 inches.
83. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein said cytoplasmically male sterile soybean plants and said male fertile maintainer soybean plants of step (a) each possess a day length sensitivity which generally corresponds to that of said location of step (a) and the area where the seeds capable of growing said cytoplasmically male sterile soybean plants are to be grown.
84. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein said cytoplasmically male sterile soybean plants and said male fertile maintainer soybean plants of step (a) each possess substantially the same flower coloration.
85. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein said cytoplasmically male sterile soybean plants and said male fertile maintainer soybean plants of step (a) each possess purple flowers.
86. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein water is applied by irrigation during step (b) for a period of approximately 0.1 to 15 days prior to the with-holding of irrigation water in step (c).
87. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein water is withheld in step (c) for a period of at least 8 days.
88. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein water is withheld in step (c) for a period of approximately 10 to 15 days.
89. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein said pollen-carrying bees of step (d) are primarily honeybees.
90. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 89 wherein honeybee hives are provided in pollinating proximity to said location of step (a) at a rate of at least 2 hives per acre of said substantially uniform populations of soybean plants.
91. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein following step (d), steps (b), (c), and (d) are successively repeated at least one time prior to step (e).
92. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 76 wherein a supplemental pollen source for said pollen-carrying bees is provided in addition to the pollen formed on said male fertile maintainer soybean plants of step (a) in order to provide ample pollen to support said pollen-carrying bees.
93. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants comprising:
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially uniform population of male sterile soybean plants wherein said male sterility is attributable to the combination of an atypical Cms cytoplasm and two distinct pairs of recessive genes r1r1 and r2r2 in pollina-ting proximity to a substantially uniform population of male fertile maintainer soybean plants which possess an N cytoplasm and two distinct pairs of recessive genes r1r1 and r2r2, which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile plants which are capable of growing additional male sterile plants, (b) applying water via irrigation to said substantially uniform populations of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation within each of said populations, (c) withholding irrigation water from said plants of said substantially uniform populations at a time when flowers are present within each of said substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said male sterile soybean plants and said male fertile maintainer soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) selectively recovering the seeds which have formed on said substantially uniform popula-tion of sterile soybean plants.
(a) growing at a location which normally experi-ences limited natural rainfall when soybean flowering occurs during the summer a substan-tially uniform population of male sterile soybean plants wherein said male sterility is attributable to the combination of an atypical Cms cytoplasm and two distinct pairs of recessive genes r1r1 and r2r2 in pollina-ting proximity to a substantially uniform population of male fertile maintainer soybean plants which possess an N cytoplasm and two distinct pairs of recessive genes r1r1 and r2r2, which when crossed with said male sterile soybean plants enable the formation of seeds on said male sterile plants which are capable of growing additional male sterile plants, (b) applying water via irrigation to said substantially uniform populations of soybean plants of step (a) as required to promote normal plant growth up to at least the time of the onset of flower formation within each of said populations, (c) withholding irrigation water from said plants of said substantially uniform populations at a time when flowers are present within each of said substantially uniform populations for a period of time during which no appreciable natural rainfall occurs so as to induce enhanced nectar flow within said flowers which serves to render the flowers more attractive to bees, (d) crossing said male sterile soybean plants and said male fertile maintainer soybean plants with the aid of pollen-carrying bees which are attracted to said enhanced nectar flow whereby seeds are formed on said male sterile soybean plants, and (e) selectively recovering the seeds which have formed on said substantially uniform popula-tion of sterile soybean plants.
94. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein with respect to said male sterile soybean plants of step (a) said atypical Cms cytoplasm was derived through its female parent from an appropriate cytoplasmic source, and in which said recessive genes r1r1 were derived through its male parent from a first gene source which possessed said r1r1 genes, and in which said recessive genes r2r2 addi-tionally were derived through its male parent from a second gene source which possessed said r2r2 genes.
95. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 94 wherein with respect to said male sterile soybean plants of step (a) said atypical Cms cytoplasm was derived through its female parent from a Mandarin cytoplasmic source, and in which said recessive genes r1r1 were derived through its male parent from a Dunfield germplasm base and in which said recessive genes r2r2 additionally were derived through its male parent from a Tokyo germplasm base.
96. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 95 wherein with respect to said male sterile soybean plants of step (a) said atypical Cms cytoplasm was derived through its female parent from the Elf variety, and in which said recessive genes r1r1 were derived through its male parent from the Bedford variety, and in which said recessive genes r2r2 additionally were derived through its male parent from the Braxton variety.
97. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 93 wherein the flowering period at said location for said male fertile soybean plants of step (a) commences before the flowering period for said male sterile soybean plants of step (a) and ends after the flowering period for said male sterile plants.
98. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein said substantially uniform populations of male sterile soybean plants and male fertile maintainer soybean plants are grown in alternating strips.
99. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F hybrid soybean plants according to Claim 93 which includes the additional step of selectively recovering seeds formed on said substantially uniform population of male fertile maintainer soybean plants grown in step (a).
100. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein said male fertile maintainer soybean plants grown in step (a) are a pure line variety.
101. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein said limited natural rainfall when soybean flowering occurs during the summer is normally less than 4 inches.
102. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 9 wherein said limited natural rainfall when soybean flowering occurs during the summer is normally less than 2 inches.
103. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein said male sterile soybean plants and said male fertile maintainer soybean plants of step (a) each possess a day length sensitivity which generally corresponds to that of said location of step (a) and the area where the seeds capable of growing said male sterile soybean plants are to be grown.
104. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein said male sterile soybean plants and said male fertile maintainer soybean plants of step (a) each possess substantially the same flower coloration.
105. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein said male sterile soybean plants and said male fertile maintainer soybean plants of step (a) each possess purple flowers.
106. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein water is applied by irrigation during step (b) for a period of approximately 0.1 to 15 days prior to the with-holding of irrigation water in step (c).
107. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein water is withheld in step (c) for a period of at least 8 days.
108. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein water is withheld in step (c) for a period of approximately 10 to 15 days.
109. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein said pollen-carrying bees of step (d) are primarily honeybees.
110. An improved process for the efficient production of seeds capable of growing male fertile F1 hybrid Glycine max plants according to Claim 109 wherein honeybee hives are provided in pollinating proximity to said location of step (a) at a rate of at least 2 hives per acre of said substantially uniform populations of soybean plants.
111. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein following step (d), steps (b), (c), and (d) are successively repeated at least one time prior to step (e).
112. An improved process for maintaining male sterile Glycine max plants useful in the production of male fertile F1 hybrid soybean plants according to Claim 93 wherein a supplemental pollen source for said pollen-carrying bees is provided in addition to the pollen formed on said male fertile maintainer soybean plants of step (a) in order to provide ample pollen to support said pollen-carrying bees.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US779,647 | 1985-09-24 | ||
| US06/779,647 US4648204A (en) | 1984-03-05 | 1985-09-24 | Process for forming seeds capable of growing hybrid soybean plants |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1297675C true CA1297675C (en) | 1992-03-24 |
Family
ID=25117062
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000516727A Expired - Fee Related CA1297675C (en) | 1985-09-24 | 1986-08-25 | Process for forming seeds capable of growing hybrid soybean plants |
Country Status (3)
| Country | Link |
|---|---|
| CN (1) | CN1019257B (en) |
| BR (1) | BR8604566A (en) |
| CA (1) | CA1297675C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1058133C (en) * | 1997-06-13 | 2000-11-08 | 吉林省农业科学院 | Cytoplasm male sterility soybean and method for prodn. of hybrid soybean seeds |
-
1986
- 1986-08-25 CA CA000516727A patent/CA1297675C/en not_active Expired - Fee Related
- 1986-09-17 CN CN 86106298 patent/CN1019257B/en not_active Expired
- 1986-09-23 BR BR8604566A patent/BR8604566A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BR8604566A (en) | 1987-05-26 |
| CN86106298A (en) | 1987-05-13 |
| CN1019257B (en) | 1992-12-02 |
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