IL31885A - Enhancement of the yield and/or nitrogen content of plants by application of phosphorus derivatives - Google Patents

Description

ENHANCEMENT OF THE YIELD AND/ OR NITROGEN CONTENT OF PLANTS BY APPLICATION OF PHOSPHORUS DERIVATIVES This invention relates to methods for use in agriculture and horticulture by means of which the growth of plants may be modified.

The usual method of enhancing the yield of a crop is to treat the medium in which the crop is grown with fertilizers. The efficiency of utilisation of fertilizers, however, depends upon their availability coinciding with the time when the crop requires them.

Another method of enhancing the yield is to alter the environmental conditions under which the crops are grown.

We have now discovered that by the use of the comp0unds hereinafter defined we are able, by selecting the appropriate application rate to affdct the growth of plants and thereby: (a) increase the useful yield of plants as regards their quantity and/ or composition of the economically important parts of the plants and/ or (b) increase the uptake of nitrogen by the crop, thereby increasing the utilisation of the added fertilizer nitrogen and/ or increase the percentage nitrogen in the economically important part of the plant and hence its protein content.

According to the present invention a method of regulating the growth of plants is provided which comprises applying to plants, seeds or the medium in which they are grown in an amount effective to increase the yield and/or the nitrogen content thereof, a phosphorus compound d'f formula: - X w— p II — y I 31885/2 <¾ ¾ C2Q alk l. 4, 6-bi-^h sphonyl) 2-s-triazinyl or -(CH2)n -R where n is 0 - 7 and R is naphthyl or phenyl optionally substituted with halo, nitro alkylamino or alkyl groups; Y is hydroxyl, amino, /W or 2-haloethyl; or W and Y are both 2-haloethyl; and Z is hydroxyl, amino or alkylamino or salt or an ester thereof. Where W is alkyl, So - CJQ alk l is preferred. Preferably according to the invention the treated plants are subsequently harvested.

It will be realised that the response of plants to a fixed rate of application will vary from one compound to another and from one type of plant to another and that the responses of a particular plant to varying applications of the same compound will also vary. It will be further realised that whereas an amount of a compound when applied within certain limits to a plant may produce a certain effect, for example a favourable increase in yield, the same compound when applied in a different amount may produce a different result, for example a higher concentration may produce a retardation of growth, though the uptake Q f nitrogen by the plant is increased relative to controls. A still higher concentration may produce a herbicidal effect; in applying the present invention these latter concentrations are to be avoided. - — oi» unoubotitutod aliphatio group of 1 ·10 (proforably 2 ·10) oarbon atomo^ - an- w*ev&&bthvubBS. o-p aubotitutod aroma io (o»g» phonyl or naphthyl) nuolotto- -linked oitho-r dirootly or through a ohain of 1~7 (pre£er^ y~-l—^ ■ oarbon .atomo to the phoophoruo a om^ and ¾-~&ad--Z¾-y- iweubctltutod al iphatio group of 1-10 (proforably a 10) oarbon atomo¾ -Ihe- -g®B-¾ii¾ing valenoias of Yj¾ and Za whioh »aro not linlcod to tho phosphorus atora aro proforably oatiafiod by- -yd^&gen-y---alk-al-i--ineta3., . ql kg atomoy li hatic or arornati r grrmps .

As examples of compoum e invention, the following may be instanced :- Chemical Name Formula Phenyl phosphonic diamide 0 C6H5 - P - ¾ i ^fono^sodlum phen l pho^phonate 0 tl G&5 - P - 0% OH Sodium phenyl phosphonamidate 0 jl C6H5 - P - ONa NH2 Phenyl thiophosphonic diamide S n G6H5 - P - N¾ N¾ Phenyl phosphonic acid 0 II C6H5 - P - OH I OH p-chloro phenyl phosphonic acid 0 it P - OH OH p-tolyl phosphonic acid 0 H CH3G6¾ - P - OH Mono- calcium phenyl phosphonate Naphthyl phosphonic acid II Gi Benzyl phosphonic acid Bis phenyl thiophosphinic acid G6H5 Xjiaphthyl methane phosphonic acid P naphthyl methane phosphonic acid /?C1eH7C¾ ti f*—oKLorp&t yl phenyl ph ephinic 0 t! acid GlCHaCH2 P - OH ί Mono-calcium 3-phenyl phosphonate — Oa Bis (^chloroethyl) phosphinic acid 0 II - P - OH I GH2CH2GQ.

The compounds may be applied to the seeds, plants or growth medium either without a diluent or in admixture with a suitable diluent. Such diluent may be solid, liquid or slurry.

When used without a diluent they are conveniently applied to the growth medium, or to the seeds prior to sowing* When applied to plants prior to planting out, a compound of the invention may be applied in admixture with a diluent to the roots of the plant.

Examples of solid diluents which may be used are china clay, Kieselguhr, diatomite, bentonite, talc or gypsum. The solid diluent may also comprise fertiliser materials.

In 00.Θ embodiment of the invention the compounds are incorporated with fertiliser ingredients into, for example a compound fertiliser.

Examples of suitable fertiliser ingredients are ammonium phosphate, ammonium sulphate, ammonium nitrate, superphosphates, potassium chloride, potassium sulphate or mixtures thereof. The G-P bond in the compounds is relatively stable, so that the compounds are compatible with most fertiliser salts. If desired, the fertiliser incorporating the compound may be granular, pelleted or powdered. Preferably it is granular. The fertiliser may then be applied to the medium in close proximity to the seed by known fertiliser placement techniques.

When applied to seeds the compounds may be applied in admixture with inert i, diluent which may be solid, or fluid. Examples of suitable solid diluents ; fluid are those instanced above* The liquid" may be, for example a surfactant^ or non-toxic oil or solvent. As another example of a suitable diluent may be instanced petroleum jelly.

For application to growing plants the compounds are preferably applied in the form of a solution, suspension or emulsion, in admixture with a liquid diluent. When used with a liquid diluent surface active agents may be incorporated, Examples of liquid diluents which may be used are water, dioxan, alcohols such as for instance ethyl alcohol, methyl alcohol, isopropanol, 2-ethoxyethanol, amyl alcohol and ketones such as for instance acetone or any suitable mixture of such diluents, lis will be recognised that the use of liquid diluents other than water will necessitate experiment to determine the quantity of diluent which may safely be used for particular applications. Suitable surface active agents may be selected from known anionic, cati*nic and non-ionic surface active agents, "Lissapol" (Regd. Trade Mark) is a very suitable surface active agent for the purpose.

If desired, fertiliser salts, for example such as have already been mentioned, may be dissolved or suspended in the liquid.

In one embodiment of the invention the compounds are applied in admixture with a weed killer which does not have an adverse effect on the growing crop,i. e. a selective weedkiller.

In a further embodiment compounds of the invention are applied in admixture with one another to the plants, seeds or the medium in which they are grown.

Thus, according to the present invention, there are provided plant growing regulating compositions comprising an effective amour:'; of at least one compound as hereinbefore defined in admixture with a efe en , ourfaotant, fertiliser, o woodlcjjT ar, g.

Also according to the invention there are provided seeds of potentially improved growth characteristics comprising seeds treated with at least one compound as hereinbefore defined which is capable of enhancing the useful yield of plants.

In some c ses seeds from treated plants, from plants grown from treated seeds or from plants grown in a treated medium, in each case the treatment being in accordance with the invention may be found to have improved growth characteristics* used in Compounds the invention have, been applied to monocotyledonous plants and dicotyledonous plants and have been found to enhance the growth and quality in both when applied at the correct rate. used in We have found that when a compound «f'the invention, for example bis-n-octyl phosphinic acid, was applied to some monocotyledons, for example' / barley, oats, maize or rice, as a 0«5 y foliar spray at the 2 leaf stage a band of approximately wide, where much of the tissue had senesaedj, formed across the leaf near to the base of the leaf. It would appear, however, that the conducting tissue remained functional since the leaf remained green on either side of the senescent band. In addition the tip of the 3rd leaf was withered but the subsequent growth had normal appearanoe.

When the foliar spray was applied at the 4- leaf stage the band of senescent tissue was noted on the h leaf and the tip of the 5th leaf.

When this compound was applied to a matured 2nd leaf of a maize plant, care being taken to avoid the solution coming into contact with the growing point of the plant, the subsequent 3rd leaf was produced with a band of senescent tissue as described above.

When an immature 3rd leaf was so treated the band of senescence appeared on the 3rd leaf and the expected withering at the tip of the 4-th leaf.

This indicates that a compound of the invention may be translocated within the plant from the point of application to a point of cell growth, Vi fta applied to dicotyledonous plants, for o.camplo radioh and 4-0 hours and over a period of a wcolc tho affootod- loavoo diod. Tho plants-roma-unod alivo, producing.-new leavoo, but tho tota-tr crop growth wag roduaod. used in The solubility of the compounds & l the invention varies. In general, it is found that phosphonic acid derivatives are more soluble in water than phosphinic acid derivatives* However, solubility of the phosphonic acid derivatives within the scope of the invention varies. Thus, phenyl phosphonic acid and its diamide are soluble in water, whereas its calcium salt is only sparingly soluble* used in When a compound &£lthe invention is sparingly soluble in water and it is desired to apply it as a foliar spray, it may be emulsified or it may be applied in an organic solvent in which it is more readily soluble* used in In certain cases a sparingly soluble compound .e£-/the invention may be solubilised by dissolving it in a dilute solution of alkali (for example., sodium hydroxide) and then carefully adding dilute acid, for example hydrochloric acid? to neutralise excess alkali without causing precipitation. On the other hand, an insoluble calcium salt of one of the compounds of the invention may be solubilised by dissolving in dilute acid and readjusting the pH of the solution by the addition of dilute alkali, for example sodium hydroxideβ Alternatively the compound may be brought into suspension by the use of suitable emulsifying agents and applied in that form.

It will be realised that each compound must be tested individually in order to arrive at the best means of application and to determine the correct amount of compound to be applied to achieve a desirec. result with a particular plant.

When admixed with a growth medium the characteristics, for example pH of such medium must be taken into account.

When, oppliod. to a gxn-wth m&dium tho comounds may conveniently added to such an extent that the growth medium contains 2,5—500 p.p.m. (preferably 5-350 p.p.m.) by weight of active compound.

When applied as a foliar spray the compounds may conveniently be .offoot a herbioidal or rotarding aotion en-^l-ants, -However,-~for tho - purpoooo of onhanoing tho growth and uooful ield-o-f—lants,~tho oompoundeH may oonvoniontly bo applied at rates of 0.01-10 lb./acre (preferably 0.05-7,5 lb./acre) of active compound, It will be appreciated that compounds of the invention may be admixed with a suitable solid or liquid diluent in any desired proportion, for application to the plants, seeds or media in which they are grown so long as the proportion used enables the compound to be applied at the desired rate without unduly high local concentrations of compound being formed when applied. In this respect, a foliar spray would conveniently contain from 0.05$ w/v to 5% w/v of active compound.

Preliminary tests with chickens on the feeding value of grain produced from seed or plants treated with a compound of the invention have not any indicated that there is ·»©· deleterious effect resulting from their use, The following examples illustrate the effect of compounds of the invention on the growth of plants.

In all the examples, unless otherwise stated, the results are expressed on a "dry matter" basis. The results given are the average of 3 replicates per test and are measured against control tests which are also the average of 3 replicate tests. All Nitrogen uptake figures are based on the duplicate determinations of nitrogen in samples talcen from each test and percentages yield. Concentrations expressed as parts per millions (p.p,m.)/are expressed on a weight basis.

Unless otherwise stated in the following examples the* pH of the medium had a value within the range 5,9 - 6.3, Tests have confirmed that where an increase has been obtained in the nitrogen content of the economically useful part of the plant, this C^ increased nitrogen is not due to nitrate or nitrite content* EXAMPLE 1 In this example compounds according to the invention were added at the rate of 100 p.p.m. of compound/ ot of growth medium which consisted of 21 lb. of a mixture of 2 parts of sand and 1 part of soUL, The pH of this mixture was approximately 6,0. The pots were also supplied with 120 p^p.m, of nitrogen in the form of ammonium nitrate, 200 p.p.m* of P2O5 in the form of dicalcium phosphate, 150 p.p.m. of K20 in the form of potassium sulphate, 100 p.p.m. magnesium sulphate and 50 p.p.m. Nad. 0 seeds of YMER barley were sown in each pot. Soon after emergence of the young plants (at one and a half leaf stage) the plants were thinned to 35 plants/pot. During growth the pots were kept in a greenhouse under natural lighting conditions, no supplementary lighting being supplied.

Heating to maintain a minimum night temperature of 55°F was supplied as necessaryc Control experiments similar to the above, but omitting the compound of the invention, were carried out under the same conditions. The results were as follows Qompound Grain Yield Nitrogen Uptake increase increase over control over control < % 2,4· dichloro phenyl phosphonic acid 12 8 Mono-calcium p-chlorophenyl phosphonate 9 7 2, ·*5 trichlorophenyl phosphonic acid 9 H Phenyl phosphonic acid 14· 15 Bis naphthyl phosphinic acid 8 4· Bis-n-octyl phosphinic acid l6 15 Increases were obtained in the grain/straw ratio of plants from pots treated with the compounds, when compared with the control tests* EXAMPLE 2 In this fi33U3plB whi^h further illuirfetsrfces the ,ftnhn_aosnen.i; according to of yj.alds obtained by use of compounds -af/the invention, the conditions of test were similar to those of the previous example except that the rate of application of the active ingredient was 25 p.p.m./pot. The crop was barley, Compound Grain Yield Nitrogen Uptake increase increase over control over control 3,4- dichlorophenyl phosphonic acid 12 15 Mono-calcium benzyl phosphonate 20 19 Mono-calcium phenyl phosphonate 11 17 2,4? 5 trichlorophenyl phosphonic acid 8 16 Increases were obtained in the grain/ straw ratio of plants from pots treated with the compounds, Bh_¾a compared with the control tests.

EXAMPLE 3 In this example the conditions of test were as in Example 1 except that the rate of application was 5 p.p.m. of active ingredient per pot.

Again the enhancement of yield is demonstrated on barley.

Compound Grain Yield Nitrogen Uptake increase increase over control over control Bis phenyl thiophosphinic acid 7 17 naphthyl methane phosphonic acid 13 17 Mono-calcium phenyl phosphonate 17 17 Mono-calcium p-chlorophenyl phosphonate 12 15 Mono-calcium benzyl phosphonate 10 17 3-chlorophenyl phosphonic acid 8 14 2,4, trichlorophenyl phosphonic acid 13 9 Bis-n-octyl phosphinic acid 14 14 EXAMPLE "' *■■ used in The effect on growth enhancement of application of the compounds i-e£ the invention at various rates of addition is demonstrated "by the following tests carried out on barley.

Compound Rate of addition % increase ia Grain p.pem./pot Yield over control 2,-4 dichlorophenyl phosphonic acid 5 0 3 100 12 Phenyl phosphonic acid 5 1 5 100 ISXAMPLE 5 The suppressant action of compounds according to the invention is increasing illustrated by this example, from which it will be seen that by varying the amount of active ingredient applied to the medium the yield may be suppressed. Neve theless under such conditions the nitrogen content of the crop may^stfll be e±aiced(see sample 14). or onhanood. The conditions of test were as in Example 1. The crop was barley.

Compound Rate of addition % increase in Grain p.p.m./pot Yield over control Bis p-chlorophenyl phosphinic acid 5 +5 25 -9 100 Bis phenyl thio phosphinic acid 5 +7 -5 100 -9 ^naphthyl methane phosphonic acid 5 +6 0 100 -17 Mono-calcium p-chlorophenyl phosphonate 5 +12 H 100 -3 Compound Rate of addition % increase in Grain Yield over control Bis-n—omyl phosphinic. acid 5 +8 -1 100 -7 Phenyl phosphonic diamide 75 +15 150 -13 300 -70 used in This example illustrates that the amount of a compound -»£ the invention to be added to the medium to achieve a desired effect varies from compound to compound and that testing is necessary to determine the optimum amount of a compound to be used to obtain the desired effect, EXAMPLE 6 In Example 5 the beneficial effect of phenyl phosphonic diamide was demonstrated at a level of 75 p«p»m* by weight. Thia experiment was carried out under a full nitrogen fertilisation regime. A separate experiment in which the same amount of phenyl phosphonic diamide was added was carried out with reduced nitrogen level (a quarter of full level) when an increase in grain yield of 22$ was obtained. The total nitrogen uptake was similar as the nitrogen content of the grain was maintained, EXAMPLE 7 used in This example illustrates the use of a compound -e# the invention as a foliar spray under field conditions.

Trial plots wore sown with barley (variety YMER). The fertiliser application was made at the rate of 3 cwts/acre of a compound fertiliser containing 20$ nitrogen, U~$ P205 and 1 > KjjO. A compound 't¾ invention, phenyl phosphonic acid, was applied to plots as a foliar spray of concentration 0,5$ w/v at rates of 1 lb,/acre and lb*/aare at the 3 leaf stage of growth* The results were as followss~ Crop Barley '~ Rate of application 1 lb. lb.

Grain Yield increase over 20 7 control % Nitrogen uptake increase 30 9 over control % EXAMPLE 8 according to A compound s£ the invention phenyl phosphonic acid was applied as a foliar spray under field conditions to oat plants at the 3 leaf stage of growth with fertiliser application as in Example ¾.

Rate of application Grain Yield Nitrogen Uptake Increase over control increase % over control EXAMPLE 9 according to Compounds ©£ the invention were added at various rates to pots of soil/sand mixture supplied with added fertiliser ingredients as in Example 1, 12 seeds of radish were sown in each pot. Soon after emergence the young seedlings were thinned to 8 plants/pot and allowed to grow to the point of optimum growth, i.e. to the point at which they would normally be harvested to produce good quality produce. Environmental conditions were such as to maintain a day temperature of 65-70°F and a minimum night temperature of 55°F. Supplementary lighting to supply a 20 hour day length at an intensity of 700 lumen/sq.ft. was provided. Increased yields were obtained as follows Compound Rate of application Eresh weight root Increased Root p.p»ma increase % over Nitrogen Uptake control over control Mono-calcium phenyl phosphonate Mono-calcium benzyl phosphonate' Compound Rate of application Fresh weight root Increased' Root p.p,m» increase % over Nitrogen Uptake control over control Mono-calcium benzyl 50 8 4 phosphonate EXAMPLE 10 In a paral el experiment to that of Example 9 invention Bis— n-o tyl phosphinic acid and mono-calcium phenyl phosphonate were added at various rates to pots of sroil/ sand medium as in Example 9, and radish were sown, grown and harvested as in that example* that high rates of application may depress the The results illustrate tho varying off oot hioh may bo obtainod οη· total yield of the crop (as in Exarrple 5). planto by tho variation of tho r-ato of applioation-t Compound Rate of application Fresh weight P*P¾:I1» , root yield increase over control .% Mono-calcium phenyl phosphonate 200 -75 50 -15 +29 Bis-n-octyl phosphinic acid 200 -20 50 -3 +15 EXAMPLE 11 according to A compound -»f the invention, mono— calcium phenyl phosphonate, was applied to a crop of radish as a 0. $ w/v foliar spray to "run off" . The radishes were grown in a soil/sand medium as in Example 9 without any addition of a compound of the invention to the medium and under the same environmental conditions.

The fresh root weight yield of the radishes was increased by U$>% EXAMPLE 12 according to A compound the invention was added at Tarious rat,js to pots of soil/ sand mixture supplied with added fertiliser ingredients as in Example 1 except that there was no added nitrogen, 20 clover seeds were sown in each po an nne a a a er s age o p an s po . nv ronmen a c o were as in Example 9» The crop was harvested after 12 weeks* Compound Hat© of application Fresh weight yield Nitrogen Uptake p.p.K , increase over increase yield control % over control % Ethyl ester of 2,Λ>6 100 32 triazine triphosphoric acid 25 15 18 EXAMPLE 13 according to Compounds ·©£· the invention were added as foliar sprays to ©lover grown as in Example 12· The application was made as 0,5$ w/v solution to "run off" at the 6 trifoliate leaf stage of growth. The plants were harvested 12 weeks after sowing.

Compound Fresh weight Nitrogen Uptake increased yield increased yield over control Mono-calcium phenyl phosphonate 20 20 Mono-calcium benzyl phosphonate 13 16 Bis-n-octyl phosphinic acid 19 25 EXAMPLE 1 according to A compound -©# the invention, phenyl phosphonic acid was admixed with fertiliser ingredients to form a compound fertiliser having an approximate analysis 20% nitrogen, ~U$ P2O5, 1 > K20 and having incorporated therein 2,5 by weight of the compound. The so treated fertiliser was applied to prepared test plots at the rate of 3 cwt./acre. Plots were seeded with Italian ryegrass and Perennial ryegrass. Control plots were laid down at the same time.

Inspection of the plots after 16 weeks shewed that the growth of grass was markedly increased in the plots treated with phenyl phosphonic acid. In pot experiments using ryegrass as the test crop a compound according o the inven on, pheny phosphonic diami e, was incorpora e i n the growth medium at a rate of 250 p,p.m. by weight, together with sufficient nutrients to ensure complete growth, Oontrol pots similar in all respects to the test pots but omitting the »ompound were also prepared and all pots sown with the same amount of seed. The yield of grass from pots treated with the compound was reduced by about 10$ when compared to the control, but the nitrogen uptake by the grass in the treated pots was increased by almost 50 This experiment illustrates according to It 'has boon found/ that compounds θί the invention may, if applied in sufficient quantity, be used to retard the growth of grass. Such application has the additional effect of intensifying the green colour of the grass during the growing season and of enabling this colour to be maintained during the winter months, EXAMPLE 15 according to Compounds -βί the invention were applied at the rates shown to boxes containing 14¾" lb, of John Innes No, 1 Compost and having 60 p,p.m, by weight of nitrogen as ammonium nitrate incorporated therein. Lettuce seeds (variety Neptune) were sown in the boxes and the seedlings thinned t* two plants/box. The environmental conditions were as in Example 9· The lettuce were harvested 13 weeks after sowing, Compound Rate of application Fresh weight yield Nitrogen Uptake p«p.m, increase over increase yield control % over control % Bis-n-octyl phosphinic 250 17 2 acid Bis-n-octyl phosphinic 75 6 42 acid Bis-n-octyl phosphinic 25 21 -3 acid Sompound Rate of application Fresh weight yield Nitrogen^tJptake p .p »m. increase over increase yield control. % over control % Ethyl ester of 2,4,6 25 24 17 triazine tri- phosphonic acid Mono-calcium phenyl 25 20 29 phosphonate Mono-calcium benzyl 75 50 53 phosphonate Mono- calcium benzyl 25 21 21 phosphonate EXAMPLE 16 according to A compound ·Θ£ the invention, ethyl ester of 2,4>6 triazine t3?ip oeph.

EXAMPLE 17 according to Compounds e£-the invention were applied, at the rates shown, to pots of soil/ sand medium. Turnip seeds were sown in the pot and later thinned to 3 plants/pot. The plants were grown under similar environmental conditions to those of Example 9 · The crops were harvested 12 weeks after sowing.

Compound Rate of application Plant Yield Nitrogen Yield p. p.m. increase over increase over control % control % Mono-calcium phenyl 10 24 10 phosphonate Mono-calcium benzyl 200 42 41 phosphonate Compound Rate of application Plant Yield Nitrogen Yield P¾P« » increase over increase over control $ control $ Mono-calcium benzyl 50 12 11 phosphonate EXAMPLE IS according to A compound &£ the invention, mono-calcium benzyl phosphonate was applied as a 0.5$ w v foliar spray to "run off" to turnip plants at the 4. leaf stage of growth* The turnips were grown as in Example 17, The crops were harvested 12 weeks after sowing and the treated plants gave a 9$ increase in dry weight over a control test, EXAMPLE 19 Ymer barley was grown in pots as in Example 1 except that the according to environmental conditions were those used in Pbcample 9. The compound the invention treated, mono-calcium benzyl phosphonate, was admixed with the medium at the application rate of 5 p.p.m. A 16% grain yield increase over control and a 19 increased nitrogen uptake over control were obtained, EXAMPLE 20 Pots of Ymer barley grown as in Example 19 were foliar sprayed with according to compounds of the invention. The concentration used was 0.5$ w/v and the compound was applied at rates equivalent to 0.2 lb., 1 lb. and 6 lb.fa. ere, The results obtained were as follows:- Compound Rate Stage of Grain Yield Nitrogen Uptake lb./aere application increase over increase over control % control $ Mono-calcium benzyl 2 leaf 30 23 phosphonate Bis-n-octyl phosphinic 0 2 leaf 18 28 acid Bis-n-octyl phosphinic 0 leaf 36 20 acid Bis benzyl thiophosphinic 4 leaf 25 10 acid EXAMPLE 21 Compounds according to the invention were added at the rates shown to pots containing a soil/sand medium and an adequate supply of phosphate, potash and minor plant nutrients. The nitrogen addition in the growth medium was at a level of 4-5 p.p.m. nitrogen, if necessary being supplied in the form of ammonium nitrate. In one instance the nitrogen level in the growth medium was p.p.m. nitrogen. The crop tested was oats.

Compound Rate of addition Grain Yield Nitrogen Uptake p.p.m. increase over increase over control % i control % ι Phenyl phosphonic diamide 250 23 63 Phenyl phosphonic diamide 250 20 6 (+45 p.p.m. nitrogen) p-nitro phenyl phosphonic acid 50 7 5 Benzyl phosphonic acid 50 12 13 diamide Phenyl thiophosphonic 250 30 4-6 EXAMPLE Maize (variety SA 200) was grown in test plots under normal field conditions in rows 3 ft. apart with 1 ft. between plants. At planting a fertiliser dressing of 3 cwts./acre of a fertiliser containing 6% nitrogen, 9$ P2O5 and 12$ 20 was appliedo At a later stage of growth when plants were 15 inches high a further dressing of 100 lbs./acre of urea (eontaining nitrogen) was applied. according to Foliar applications of compounds «£ the invention at the 4· leaf stage of growth were made to the test plots at various rates with the following results. Results are the mean of 6 replicate tests.

Compound, ' Rate of Grain, Yield Ear Plant Nitrogen Uptake applicatio iricroase oyer . ratio · increase over lbs./acre control % control % Benayl phosphonic 0.25 4.0 I.03 - acid 1.0 10.0 I.03 12 4.0 18.0 0.99 18 Compound Rate of Grain Yield Ear Plant Nitrogen.uptake application increase over ratio increase over lbs./acre control % .control % Phenyl phosphonic 0.25 11.0 1.87 acid Control 0.91 EXAMPLE 2.3 Soya beans (variety Masterpiece) were grown in test plots under normal field conditions in rows 3 ft. apart. The seeds were sown at the rate of 4-0 lbs»/acre. Fertiliser dressings were applied as outlined in Example 22. according to A compound e# the invention was applied to the seeds in admixture with separated milk to obtain adherence of the compound to the seed.

Results quoted are the mean of 6 replicate tests and are compared to control plots which were grown with untreated seed.

Compound Rate of application Fresh Weight Yield Nitrogen Uptake to seed X% u/v) increase over increase over control % control % Calcium benzyl a phosphonate EXAMPLE 2A according to A compound the invention, phenyl phosphonic diamide, was applied to pots of soil/sand medium at the rate of 150 p.p.m. The pots were sown with wheat and grown in the open under bird-proof cages.

Each pot was otherwise as treated in Example 1 with respect to fertiliser application and methods of sowing and thinning. After 10 weeks under these conditions the pots were brought indoors and kept under the environmental conditions of Example 9 for a further 4· weeks after which time the crop was harvested. An increase in dry weight yield of 14$ was obtained* The pH of the medium in this example was 5.8.

EXAMPLE 25 Barley plants were grown in pots under the conditions of Example 1 an -un er env ronmen a con ons o xamp e · according to Gompounds the invention were applied to the growing plants as foliar sprays at the 2 leaf stage of growth Compound Rate of addition Increase Grain Increased (lbs ./acre) Yield over Nitrogen Uptake control % over control % Mono— calcium benzyl phosphonate 1 30 23 Ethyl ester of 2,J+, o triazine 2* 10 9 triphosphonic acid Bis S chloroethyl) phosphinic 0c5 acid Phenyl J& chloroethyl phosphinic 2* 12 acid Mono-calcium 3-phenyl propyl phosphonate EXAMPLE 26 Barley (variety Olli) was grown in pots as in Example 1 and under according to the environmental conditions of Example 9» Compounds -θί the invention were mixed into the medium at the rates shown. The crops were harvested after 14. weeks and compared with controls grown under the same conditions.

Compound Rate of addition Grain Yield Nitrogen Uptake •p«P oftL« : increase over increase over control % control Mono-calcium phenyl 50 21 20 phosphonate chloroethyl phenyl 50 23 2 phosphinic acid 10 19 13 Bis ethyl amino phenyl 50 U 12 di(ethylamide) phosphonic aidr Diethyl ester of 2 ,4,6 50 8 13 triazine triphosphonic acid EX&MPLE 27 - according to Thie example illustrates the use of a compound the invention in admixture with fertiliser ingredients under field conditions.

A. granular concentrated complete fertiliser was prepared incorporating 2,5% phenyl phdsphonic acid. The fertiliser formulation was such as would have given an analysis of 20% nitrogen, 11$ total P2O5 and ±0> K20 if no phenyl phosphonic acid had been added. It was considered that the amount of dilution brought about by the addition of the phenyl phosphonic acid was negligible for the purposes of the test.

The fertiliser was applied to prepared plots at the rate of 3 cwts./acre by placement in the soil adjacent to the seed at the time of sowing. The crop used was barley (variety YMER) and a control test was carried out at the same time.

Grain Yield increase over control % 7 Nitrogen Uptake increase over control % 1& Thus, although the fertiliser application was marginally less than the fertiliser applied to the control, there was a substantial nitrogen uptake increase.

EXAMPLE 28 according to can Some of the compounds &£■ the invention/exhibit a strong suppressant action as illustrated by the following tests carried out on barley under the conditions of Example 1. Nevertheless nitrogen uptake may still be increased, as in Example 14.

Compound Rate of addition % increase in p.p«mf yield over control, -Eriphonyl phoophino oxido —§— ■ - ■ -35- -±θθ- — s-p-chlorobenzyl phosphonic acid 5 -2 -7 100 -79 ■Ruto of addition p»p»m» yield over control Big php yl phosphiaothioy-L. aootio aoid EXAMPLE 29 a according to In order to demonstrate that tfee compound^ o# the invention are not deleterious to germination when applied as a seed dressing, 2% by weight of phenyl phosphonic diamide was applied with 1.5 by weight of petroleum jelly to oats seeds. Laboratory germination tests showed that there was no diminution in germination with these seeds compared with those coated with 1.5% petroleum jelly only or uncoated seeds* EXAMPLE: 30 according to Seeds from a plant grown from seed treated with a compound ·Θ£ the invention, phenyl phosphonic diamide, were subjected to routine seed germination tests. The results of the test showed a high germination rate (90-100 ) comparable with that of good quality seed from untreated plants.

Claims (23)

31895/2 What we claim is:

1. A method of modifying the growth of plants which comprises applying to plants, seeds, or the medium in which they are goxwn, in an amount effective to fejahance the yield and/ or the nitrogen content thereof, a phosphorus compound of formula: wherein X is oxygen or sulphur; W is ai - C2n alkyl, 4, 6- dialkyl bisphosphonyD-2-s-triazinyl or -(CH2)n -R where n is 0 - 7 and R is naphthyl or phenyl, optionally substituted with halo, nitro, and alkyl groups; Y is hydroxyl, amino, alkylamino* W or 2-haloethyl; or W and Y are both 2-haloethyl: and Z is hydroxyl, amino or alkylamino; or a salt or an ester thereof.

2. A method as claimed in claim 1, wherein the plants are subsequently harvested.

3. A method as claimed in either of claims 1 or 2 wherein W is cio alkyx-

4. A method as claimed in either of claims 1 or 2 wherein the phosphorus compound is a compound of formula: zy't · 31895/2 wherein m and n are 0 - 3 and R' is halogen or alkyl; or a salt, dster or amide thereof.

5. A method as claimed in either of claims 1 or 2 wherein the phosphorus compound is phenyl phosphonic acid or a salt, ester or amide thereof.

6. A method as claimed in either of claims 1 or 2 in which the phosphorus compound is 3-phenyl-propylphosphonic acid or a salt, ester or amide thereof.

7. A method as claimed in either of claims 1 or 2 wherein the phosphorus compound is p-chlorobcnzylphosphonic acid or a salt ester or amide thereof.

8. A method as claimed in either of claims 1 or 2 wherein the phosphorus compound is bis-n-octyl phosphinic acid or a salt, ester or amide thereof.

9. A method as claimed in any of claims 1 - 8 in which the plants are monocotyledons.

10. A method as claimed in claim 9 in which the plants are cereals.

11. A method as claimed in any of claims 1 - 8 in which the plants are dicotyledons.

12. A method as claimed in any of claims 1 - 8 in which the plants are wheat, barley, oats, maize, rice, clover, lettuce, radish, turnips, or soya beans.

13. A method as claimed in any of claims 1 - 8 wherein the plants are grass. \ 31895/2

14. A method as claimed in claim 13, wherein the phosphorus compound is applied to grass in an amount sufficient to enhance the nitrogen content thereof.

15. 16. A method as claimed in any of claims 1 - 14 in which the phosphorus compound is applied to the plants as a foliar spray a rate of 0· 001 - lO lb/acre.

16. A method s claimed ir claim 15 in which the phosphorus compound is applied at a rate of 0· 05 - 7· 5 lb/ acre.

17. A method as claimed in any of claims 1 - 14 in which the phosphorus compound is applied to seeds as a seed dressing composition.

18. A method as claimed in any of claims 1 - 1 in which the amount of the phosphorus compound applied is such that the growth medium contains 2- 5 - 500 ppm by weight thereof.

19. A method as claimed in claim 18 in which the amount of the phosphorus compound applied is such that the growth medium contains 5-350 ppm by weight thereof.

20. A method as claimed in any of claims 1 to 19 wherein the phosphorus compound is applied in admixture with inert diluent, surfactant, fertilizer or selective weedkiller,

21. Seeds or growth media treated by a method claimed in any of claims 1 - 14, 17 or 20.

22. A composition for enhancing the growth of plants comprising a phosphorus compound as defined in any of claims 1 and 3 - 8 and a fertilizer,

23. A method as claimed in any of claims 1 - 20 substantially as hereinbefore described with reference to any of Examples 1 - 30.