CN113796309B - Method for breeding maize inbred line parents by enhancing heterosis in different ecological regions - Google Patents

Abstract

The invention discloses a method for breeding maize inbred line parents by enhancing heterosis in different ecological regions. The method takes the machine-harvested germplasm resources suitable for Huang-Huai-Hai areas as a base material, and the male parent group creates and adds the heat source QR273, so that the close-tolerance machine-harvested characteristic of a temperate zone inbred line is reserved, and meanwhile, the broad-spectrum disease resistance of tropical germplasm is permeated. The female parent is selected in Henan in the north and the male parent is selected in Fujian in the south, so that the parents are selected naturally and then manually, and the difference of the parent genes for selecting and breeding in different ecological areas is large, thereby achieving the purpose of enhancing the heterosis. The breeding method disclosed by the invention is strong in practicability, strong in operability, clear in purpose and high in breeding efficiency, and can be popularized and applied in corn breeding.

Description

Method for breeding maize inbred line parents by enhancing heterosis in different ecological regions

Technical Field

The invention belongs to the technical field of crop breeding, and particularly relates to a method for breeding corn inbred line parents by enhancing heterosis in different ecological regions.

Background

Heterosis is a common biological phenomenon, which is a phenomenon that a hybrid produced by hybridizing two parents with different genetic compositions exceeds parents in the aspects of growth vigor, vitality, stress resistance, adaptability, yield, quality characters and the like. Maize is a cross-pollinating plant, and maize breeding mainly utilizes heterosis. The heterosis has close relation with the source of the parent inbred line, and the heterosis is stronger when the genetic difference between the inbred lines is larger. For decades, scholars at home and abroad discuss the heterosis group of the maize inbred line by methods such as genetic relationship, morphology, quantitative inheritance, isoenzymes, molecular marker technology developed in recent years and the like, and are beneficial to improvement and innovation and germplasm resource widening.

The high-yield breeding of the corn is based on germplasm innovation, and the heterosis level is improved through combination and matching. A very serious problem faced by China at present in corn breeding is increasingly narrow and deficient germplasm resources, in recent years, the problem of genetic simplification of the existing corn varieties in Huang-Huai-Hai regions is more and more serious, the innovation road is more and more narrow, and the symptom is that new germplasm is lacked. In the process of urbanization, mechanical operation, particularly mechanical harvesting, adjusts the breeding direction of the forced Huang-Huai-Hai region, and the early maturing, close planting resistance and stress resistance enhancement become the mainstream direction, and all of the main flow is to be implemented on the improvement and innovation of excellent germplasm.

The introduction, identification, improvement and utilization of foreign germplasm are one of the most effective ways for widening the current germplasm basis. The variety, population, hybrid or inbred line of the American corn belt and the like play an important role in the development of corn breeding and production in China. The germplasm has the advantages of wide adaptability, high combining ability and the like. In particular, the Di Ka series which is suitable for mechanical harvest and sold in comparative fire in recent years: the Di Ka 517, di Ka 653, di Ka 6361, yu Tian 9953 and Yu Tian 888 approved by Nangda of Henan, all utilize the characteristics of being suitable for mechanical and mechanical harvesting. And tropical and subtropical germplasm from a maize diversity center, including maize germplasm in low-latitude regions of central south America, africa and southeast Asia, has different genetic variability and special stress resistance, disease resistance and special adaptability of maize germplasm in China and even America, and is characterized by dark green leaf color, long green-keeping period, developed root system and tough stems. The genetic diversity is distant from the temperate germplasm geography, the genetic communication is less for a long time, and the genetic diversity is large. The tropical and subtropical maize germplasm is applied to temperate breeding, and plays an important role in the improvement of the prior temperate germplasm dominant group and the selection and construction of a new hybrid-optimal mode.

The amplification, improvement and innovation of germplasm must also follow the principle of heterosis group to raise breeding efficiency. The heterosis patterns in different ecoregions are not completely the same, and in the continuous development and change, the original advantage groups and patterns can be continuously improved and perfected. The maize growth is greatly influenced by climate, so is the inbred line breeding, and a main obstacle of the utilization of tropical and subtropical germplasm is that the tropical and subtropical germplasm is sensitive to photoperiod reaction under the condition of temperate zone and long sunshine. Beginning in 2016, the Agrimonial Hospital collaborated with brother units such as Guizhou, fujian, and Showa Country. With the same basal population: the Suwan changes the Iodent population, and the low generations F1 and F2 are sown in summer (selected in the north) in Henan, and are divided into 3 parts later, which are respectively selected in Fuzhou (ecological region in southeast of China), yunnan (ecological region in plateau in southwest) and Henan (ecological region in Huang-Huai-Hai). The Fuzhou selected line shows longer growth period and strong leaf resistance, and the test seeds (15S 717, T4575) in the summer seeding area of Henan have the characteristics of strong resistance, good quality and good high yield, and the effect of the selected line in Henan is not as good as the advantage of the ecological selected line in the southeast area. The materials which are too excessive and are deviated to the heat zone are selected in the ecological region in Yunnan, so that the phenomenon of water and soil inadequacy is shown in the north of late generation.

The adaptability of the maize germplasm material in the ecological region is similar to the gene convergence selection type in the ecological region, namely, most of contributing genes (yield, resistance and environment-adaptive genes) of the material in the same climatic environment present environmental tendency in the selection process. The heterosis mechanism is used to explain: the larger the gene difference, the higher the richness and the stronger the heterosis. Based on the method, the hybrid parents are selected by utilizing different ecological area environments, the heterosis is enhanced, and a basis is provided for breeding a good maize inbred line.

Disclosure of Invention

The method for breeding the maize inbred line parents by enhancing the heterosis in different ecological areas provided by the invention takes the machine-harvested germplasm resources in Huang-Huai-Hai areas as basic materials, and the heat source QR273 is added in the creation of male parent groups, so that the characteristics of density tolerance and machine-harvested property of temperate inbred lines are maintained, and meanwhile, the broad-spectrum disease resistance of tropical germplasm is permeated. The female parent is selected in Henan in the north and the male parent is selected in Fujian in the south, so that the parents are selected naturally and then manually, and the difference of the parent genes for selecting and breeding in different ecological areas is large, thereby achieving the purpose of enhancing the heterosis. The breeding method disclosed by the invention is strong in practicability, strong in operability, clear in purpose and high in breeding efficiency, and can be popularized and applied in corn breeding.

The invention provides a method for breeding maize inbred line parents by enhancing heterosis in different ecological areas, which takes the accessible machine harvesting germplasm resources in Huang-Huai-Hai areas as basic materials, carries out breeding after a heat source QR273 is added into a male parent, breeds the female parent in Henan in the north and breeds the male parent in Fujian in the south according to environmental tropism, and enhances the heterosis; the method specifically comprises the following steps:

step 1, collecting, evaluating and identifying basic germplasm, and screening machine-harvested germplasm resources in Huang-Huai-Hai regions;

step 2, mixing and hybridizing the germplasm resources screened in the step 1 with a male parent heat source QR273, constructing a basic population, and breeding maternal germplasm resources with excellent comprehensive resistance, density resistance and high seed production yield and male parent resources with high prematurity and combining ability;

step 3, planting the male parent resources and the female parent resources screened in the step 2 in different ecological areas, and identifying and selecting high-quality single plants;

step 4, selecting high-quality single plants to be hybridized and combined;

and 5, selecting a corn variety with comprehensive resistance and outstanding yield by a multipoint field combination identification method.

Further, in step 1, the collection, evaluation and identification of the basic germplasm comprises the following steps:

step 1.1, evaluating and identifying the paternal population germplasm resources: carrying out evaluation and identification by using QR273, HCL645, KWS49 and PH4CV materials;

step 1.2, evaluating and identifying maternal germplasm resources: using a dicard C6361 female parent: D9102Z; dicar 653 female parent: H3659Z; good jade 99 female parent: m03; yudan 888 female parent: 15S717; 9953 female parent of Yu-Dan: 1122 (Yu-Si); zhengdan 958 female parent: zheng 58 for evaluation and identification.

Further, in step 2, the mixed hybridization for constructing the basic population comprises the following steps:

step 2.1, hybridizing and breeding 15DP10 by using QR273 and HCL645 in Fuzhou of the father group, hybridizing the 15DP10 with F1 of KWS49 and PH4CV, and selecting a premature material group on the premise of not reducing the combining ability;

2.2, constructing a base material selection system by using various female parents (D9102Z, H3659Z, M03, 15S717, yu 1122) which are suitable for machine-harvested varieties and Zheng 58 with wider adaptability examined in recent years in China; early hybrid breeding, genetic balance for 2 times, and breeding of mother stock group germplasm resources with excellent comprehensive resistance, density resistance and high seed production yield.

Further, in step 3, the selection of superior plants in different ecoregions comprises the following steps:

step 3.1, sowing the F1 generation of the male parent group seed material in the third generation, selfing and reserving seeds, and harvesting F2 generation seeds; sowing the F1 generation of the female parent group seed material hybridized by the summer sowing mixed powder in the third generation, selfing and reserving seeds, and harvesting F2 generation seeds;

step 3.2, planting the F2 generation father group seeds in Fuzhou, selfing and reserving seeds, and harvesting F3 generation seeds; planting the seeds of the F2 generation mother group in high density on the crane wall, reserving seeds by selfing, and harvesting the F3 generation seeds;

3.3, sowing the F3 generation of male parent germplasm materials harvested in summer sowing in Fuzhou in the third generation, performing selfing and reserving seeds, and harvesting F4 generation seeds; sowing the F3 generation of female parent germplasm material harvested in summer on the crane wall in the third generation, selfing and reserving seeds, and harvesting F4 generation seeds;

step 3.4, planting the F4 generation father seed material in summer in Fuzhou, selfing and reserving seeds, and harvesting F5 generation seeds; planting the F4 generation mother seed material in high density in the crane wall, selfing and reserving seed, and harvesting F5 generation seed.

Further, in step 4, the hybridization combination is to combine and combine the F5 generation father group selected in Fuzhou with the F5 generation mother group selected in the arm of the crane and the third generation mother group, and finally combine and combine 500 shares of hybrid seeds.

Further, in step 5, the multipoint field combination identification method is to perform multipoint field identification on 500 parts of the matched and combined hybrid seeds and select the variety of the dredgerfill 678 which shows comprehensive resistance and outstanding yield.

The invention also provides an amphiphile obtained by the method, wherein the amphiphile is named as a corn combination 1673, the female parent is dredged SN12E, and the male parent is 15DP10.

The invention also provides an amphiphile obtained by the method, wherein the amphiphile is named as a corn combination 1752, the female parent is a dredging heddle 68, and the male parent is a dredging M009.

The invention also provides an amphiphile obtained by the method, wherein the amphiphile is named as a corn combination 1718, the female parent is dredged SN12E, and the male parent is 15DP80.

Compared with the prior art, the method for breeding the corn inbred line parents by enhancing the heterosis in different ecological areas has the following beneficial effects:

1. according to the invention, the suitable machine-harvested germplasm resources in Huang-Huai-Hai regions are used as basic materials, and the heat source QR273 is created and added to the male parent group, so that the characteristics of close tolerance and suitable machine-harvesting of temperate zone inbred lines are retained, and meanwhile, the broad-spectrum disease resistance of tropical germplasm is permeated.

2. The invention obtains the high lodging-resistant, broad-spectrum disease-resistant, dense-resistant, high-temperature-resistant and early-maturing suitable mechanical harvesting germplasm material, and the material can be used for breeding of yellow-Huaihai suitable mechanical harvesting varieties.

3. The corn combination obtained by the method provided by the invention, namely the combination 1673 (dredged seed 678), and the corn combination 1752 and the combination 1718 has the advantages of strong disease resistance, precocity, good quality and good fructification, is suitable for being planted in summer sowing areas of Huang-Huai-Hai, and has high yield.

4. The method for breeding the maize inbred line parents by enhancing the heterosis in different ecological regions has strong practicability, strong operability, clear purpose and high breeding efficiency, and can be popularized and applied to maize breeding.

Detailed Description

The present invention is illustrated in detail below with reference to specific examples, but the present invention should not be construed as being limited thereto. The experimental methods in the following examples are conventional methods unless otherwise specified, and materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The invention provides a method for breeding maize inbred line parents by enhancing heterosis in different ecological regions, which comprises the following steps:

1. collecting, evaluating and identifying basic germplasm:

the collection and evaluation of germplasm are the precondition of the corn breeding work; the reasonable evaluation and identification of germplasm resources are the first work for improving breeding efficiency. Whether the father group or the mother group, the machine-harvested germplasm resources in Huang-Huai-Hai regions are used as basic materials.

1. Finishing evaluation and identification of paternal group germplasm resources: QR273 is a stable breeding selection in 2002 by 8 generations of selfing of Guiyang and Hainan, wherein the QR273 is a 2002 field number 273, and Suwan1 group is used as a basic material by Guizhou farm academy Chenghong researcher in 1997. The material has high combining ability, the 300 parts of inbred lines used by Sichuan agriculture generally test the combining ability, and the QR273 rank is the first; the reaction is slow to photoperiod, most heat band materials have strong photosensitivity and are difficult to be normally firmed in the north, QR273 can be normally firmed in Henan, gansu and Xinjiang, the comprehensive resistance is good, and the like, but the defects of slow seed dehydration and the like are overcome. The Iodent germplasm is deep in seed, malted, early-maturing, fast in dehydration, short in leaf, good in tightness and free of bald and sharp in ears, is an ideal germplasm material for mechanically harvested varieties, but is poor in disease resistance and lodging resistance. QR273, HCL645, KWS49 and PH4CV materials are hybridized and then are backcrossed to form Iodent, so that male parent germplasm resources which are high temperature resistant, suitable for mechanical harvest and wide disease resistance are bred.

2. Finishing evaluation and identification of maternal germplasm resources: constructing a base material selection line by using a female parent which is approved in recent years and suitable for machine-harvested varieties in China. The source of the base material is as follows: mother dicard C6361: D9102Z; dicar 653 female parent: H3659Z; good jade 99 female parent: m03; yudan 888 female parent: 15S717; 9953 female parent of Yu-Dan: yudan 1122 and Zhengdan 958 female parent with wider applicability: zheng 58. Early hybrid breeding, genetic balance for 2 times, and breeding of mother stock group germplasm resources with excellent comprehensive resistance, density resistance and high seed production yield.

2. Mixed hybridization to construct the basal population:

1. the male parent group is mainly hybridized by QR273 and HCL645, and simultaneously, in the line selection of Fuzhou, shoatong, guizhou and Crane wall, the 15DP10 breeding period in Fuzhou is late, but the combining ability is high, and the premature material group is selected on the premise of not reducing the combining ability by hybridizing the 15DP10 with KWS49 and F1 of PH4 CV.

2. Mother group base material dicard C6361 mother: D9102Z; dicar 653 female parent: H3659Z; good jade 99 female parent: m03; yudan 888 female parent: 15S717; 9953 female parent of Yu-Dan: 1122 (Yu-Si); zhengdan 958 female parent: zheng 58 carries out mixed pollination in the Mian breeding base, the powder mixing and hybridization are carried out again on the crane wall in the next year, the seeds are mixed in the early stage, the genetic balance is carried out for 2 times, the F1 generation seeds are harvested, and the line selection is started in the third year.

3. Selecting excellent plants in different ecological regions:

1. the collected and identified F1 generation of male parent group seed material is sowed in the third generation, the plants with early flowering phase are selected for selfing, and early maturing material with good resistance, developed root system and good grain quality is selected for reserving seeds during harvesting to generate F2 generation of parent group seeds. The F1 generation of female parent group seed material hybridized by the mixed powder sowed in summer is sowed in the third generation, the plants with early flowering phase are selected for selfing, and the material with good resistance, developed root system, strong fruiting performance and good seed quality is selected for seed reservation during harvesting to generate F2 generation female parent group seeds.

2. Planting the F2 generation of the three-selected male parent group seed material in Fuzhou, wherein the planting population is large due to the obvious separation phenomenon of the F2 generation, selecting single plants with excellent comprehensive resistance, bagging and selfing, and harvesting F3 generation parent group seeds; and (3) planting the F2 generation of the three-selected female parent group seed material in the large crane wall group at high density (6000 plants/mu), bagging and selfing the selected excellent single plant with lodging resistance, high temperature resistance and strong fruiting property, and harvesting the F3 generation female parent group seed.

3. Sowing F3 generations of male parent group seed materials harvested in summer sowing in Fuzhou according to ear rows, selecting plants with early flowering phase for selfing, selecting excellent individual plants in the good ear rows for reserving seeds during harvesting, and generating F4 generation parent group seeds; the F3 generation of female parent group seed material selected by summer sowing on the crane wall is sowed in the third generation according to the ear rows, the plant with early flowering phase is selected for selfing, and the excellent single plant of the excellent ear row is selected for reserving seeds during harvesting to generate F4 generation female parent group seeds.

4. Planting the F4 generation father group germplasm material in summer sowing in Fuzhou, selecting a single plant with excellent comprehensive resistance for bagging and selfing, and harvesting F5 generation father group seeds; planting the F4 generation mother seed group germplasm material in the high density (6000 plants/mu) of the crane wall, bagging and selfing the excellent single plant with lodging resistance, high temperature resistance and strong fruiting property, and harvesting the F5 generation mother seed group seeds.

4. Hybridization and combination assembly:

combining and matching the F5 generation father group bred in Fuzhou with the F5 generation mother group bred in the crane wall; finally, 500 parts of the combined hybrid seeds are assembled. The method has the advantages that different ecoregions are utilized to separately select the female parent group and the male parent group, the selected parental genes have large difference, the heterosis is more obvious, and a new corn variety with outstanding resistance, excellent quality and higher yield can be selected and bred more quickly.

5. Multi-point field combination identification method:

and (3) performing field identification on 500 newly assembled hybrid combinations in the crane wall area, wherein each hybrid combination has the row length of 4 meters, the row spacing of 2 rows and the row spacing of 0.60 meter, the planting density of 5000 plants/mu, and the field management is the same as the field production by setting Zhengdan 958. And (3) performing field yield identification, comprehensively comparing the agronomic characters and the economic characters through field investigation and indoor seed test, selecting the superior and inferior characters, screening out an excellent combination with high cooperation force exceeding the comparison by more than 10%, and continuously performing 6-point field combination combined identification such as Anyang, crane wall, zhou Kong, luoyang, luoye, unsealing and the like twice in the next year.

Example 1

Combination 1673 (dredge list 678): the female parent dredging SN12E is prepared by using foreign (south Africa) corn hybrid, introducing domestic backbone inbred line fluid 478, then introducing domestic backbone inbred line Zheng 58 as basic material, and then strictly selecting and breeding through south breeding and north breeding, continuous multi-generation inbred. The male parent 15DP10 is obtained by hybridizing QR273 with HCL645 and selfing for 6 generations continuously for 3 years.

The plant type is compact, the plant height is 280cm, the ear position is 105cm, the total leaves are 19-21, the stem diameter is 2.2cm, the leaf width is 8.7cm, the leaf color is dark green, the tassel branches are 5-7, the seedling emergence lasts for 50 days, the seedling emergence lasts for 52 days, the fruit cluster barrel type is formed, the ear length is 18.6cm, the ear thickness is 5.5cm, the ear row number is 18-20, the row number is 42, the thousand kernel weight is 340g, the seed yield is 90.8%, the half dent of the seed is half, the top end of the seed is white, the back of the seed is yellow, and the cob is red. The product can resist diseases such as leaf spot, northern leaf blight and bacterial wilt of Curvularia lunata, and has high lodging resistance. Is suitable for being planted in summer sowing areas of Huang-Huai-Hai.

Example 2:

combination 1752: the female parent dredging heddle 68 is formed by constructing a base material selection line by using female parents (D9102Z, H3659Z, M03, 15S717, yu 1122) which are suitable for machine accepting varieties and have wider adaptability in recent years in China and Zheng 58. The Dredging M009 is obtained by crossing 15DP10 with KWS49 and F1 of PH4CV and then selfing and breeding for multiple generations.

The plant height is 276cm, the ear position is 110cm, the plant type is compact, the total leaves are 19-21, the leaf color is dark green, the fruit cluster is uniform and cylindrical, the ear length is 18.9cm, the ear thickness is 5.4cm, the cob is white, the ear row number is 18-20, the row grain number is 36, the thousand grain weight is 361g, the seed yield is 90.0%, half horse teeth of seeds have bald tips, the disease resistance and lodging resistance are strong, the quality is good, and the method is suitable for being planted in Huang-Huai-Hai summer sowing areas.

Example 3:

combination 1718: the female parent dredging SN12E is prepared by introducing foreign (south Africa) corn hybrid into domestic backbone inbred line 478, then introducing domestic backbone inbred line Zheng 58 as base material, continuous multi-generation inbred, and strictly selecting and breeding. The male parent 15DP80 is the hybrid of HCL645 with artificially synthesized warm Suwan-Iodent (Suai) population mixed pollen of corn; and 6 generations of selfing are continuously carried out for 3 years.

The plant type is compact, the plant height is 285cm, the ear position is 112cm, the total leaves are 19-21, the leaf color is dark green, the fruit cluster is uniform and medium, the ear length is 18.5cm, the ear thickness is 5.5cm, the ear row number is 18-20, the row grain number is 35.6, the thousand grain weight is 377g, the seed yield is 90.1%, the half horse teeth of the grains, the spike stalk is white, the bract is loose, partial covering is incomplete, the disease resistance is strong, the early maturing is good in quality and the solidity is good, and the method is suitable for planting in Huang-Huai-Hai summer sowing areas.

TABLE 1 summary of yield of new combinations of crosses combined with multipoint field combinations

Through the analysis of the yield of the multipoint hybridization combination, researches find that 3 corn combinations with high matching force, high yield and good stress resistance are selected. From the above, it can be seen that the yield of the corn combination obtained by the method of the present invention is also greatly increased.

It should be noted that the preferred embodiments of the present invention have been described for the purpose of preventing redundancy, but that additional variations and modifications to these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (1)

1. A method for utilizing different ecological regions to enhance heterosis for breeding corn inbred line parents is characterized in that germplasm resources in Huang-Huai-Hai regions are taken as basic materials, and breeding is carried out after a heat source QR273 is added into male parents; breeding female parent in the north and breeding male parent in the south; the method specifically comprises the following steps:

step 1, collecting, evaluating and identifying basic germplasm, and screening machine-harvested germplasm resources in Huang-Huai-Hai regions; the method comprises the following steps:

step 1.1, evaluating and identifying paternal ethnic resources: evaluating and identifying by using QR273, HCL645, KWS49 and PH4CV materials;

step 1.2, evaluating and identifying maternal germplasm resources: using the dicard C6361 female parent: D9102Z, dicard 653 female parent: H3659Z, good jade 99 female parent: m03, yudan 888 female parent: 15S717, yu mono 9953 female: yu 1122, zhengdan 958: zheng 58 is evaluated and identified;

step 2, the male parent germplasm resources screened in the step 1 and a male parent heat source QR273 are mixed and hybridized to obtain male parent resources with high prematurity and combining ability, a female parent basic group is constructed, and female parent germplasm resources with excellent comprehensive resistance, density tolerance and high seed production yield are bred, and the method specifically comprises the following steps:

step 2.1, hybridizing QR273 and HCL645 in Fuzhou of the father group to breed 15DP10 with a later growth period and high prematurity combining ability, hybridizing the 15DP10 with F1 of KWS49 and PH4CV, and selecting a prematurity material group on the premise of not reducing the combining ability;

2.2, constructing a basic material selection line by using each female parent, carrying out early hybrid breeding, carrying out genetic balance for 2 times, and breeding a female parent group germplasm resource with excellent comprehensive resistance, density resistance and high seed production yield;

step 3, planting the male parent resources and the female parent resources screened in the step 2 in different ecological regions, and identifying and selecting high-quality single plants, which specifically comprises the following steps:

step 3.1, sowing the F1 generation of the male parent group seed material in the third generation, selfing and reserving seeds, harvesting F2 generation seeds, sowing the F1 generation of the female parent group seed material hybridized by the summer sowing mixed powder in the third generation, selfing and reserving seeds, and harvesting F2 generation seeds;

3.2, planting the F2 generation parent group seeds in Fuzhou, selfing and reserving seeds, harvesting F3 generation seeds, planting the F2 generation parent group seeds in the crane wall at high density, selfing and reserving seeds, and harvesting F3 generation seeds;

3.3, sowing the F3 generation of male parent germplasm materials harvested in summer sowing in Fuzhou in three generations, selfing and reserving seeds, harvesting F4 generation seeds, sowing the F3 generation of female parent germplasm materials harvested in summer sowing in the wall of the crane in three generations, selfing and reserving seeds, and harvesting F4 generation seeds;

step 3.4, planting the F4 generation parent seed material in summer sowing in Fuzhou, selfing and reserving seeds, harvesting F5 generation seeds, planting the F4 generation parent seed material in the high density on the crane wall, selfing and reserving seeds, and harvesting F5 generation seeds;

step 4, selecting high-quality single-plant hybridization combination, wherein the hybridization combination is to combine the bred F5 generation father parent group with the bred F5 generation mother parent group in three, and finally combine 500 parts of the combined hybrid seeds;

and 5, selecting a corn variety with comprehensive resistance and outstanding yield by a multipoint field combination identification method.