阅读说明：本技术 一种玉米自交系配合力高效快速检测方法 (Efficient and rapid detection method for corn inbred line combining ability ) 是由 魏建伟 卜俊周 岳海旺 陈淑萍 郭安强 孙海霞 谢俊良 彭海成 孙文芳 于 2021-07-20 设计创作，主要内容包括：本发明公开了一种玉米自交系配合力高效快速检测方法,具体涉及作物育种领域,包括步骤1、自交系创制基础材料的AB分群：将种质资源按照母本群(A群)和父本群(B群)分类；步骤2、自交系选系群体的组配与后代选择；步骤3、稳定自交系“非字型”测配；步骤4、杂交组合配合力测定及强优势组合的鉴定。本发明通过创新出了“非”字测配试验设计,大大减少了人工的投入,降低了劳动风险。(The invention discloses a method for efficiently and quickly detecting the combining ability of a maize inbred line, and particularly relates to the field of crop breeding, which comprises the following steps of 1, creating AB grouping of a base material by the inbred line: classifying the germplasm resources according to a parent group (A group) and a father group (B group); step 2, the combination of the inbred line selection population and the selection of offspring; step 3, testing and matching the stable inbred line in a non-font manner; and 4, determining the combining ability of the hybridization combination and identifying the strong dominant combination. According to the invention, a non-character testing and matching test design is created, so that the labor investment is greatly reduced, and the labor risk is reduced.)

1. A high-efficiency and rapid detection method for the combining ability of a maize inbred line is characterized by comprising the following steps: the specific detection steps are as follows:

step 1, creating AB grouping of basic materials by inbred lines: classifying the germplasm resources according to a parent group (A group) and a father group (B group);

step 1.1: selecting two typical female parent materials and two typical male parent materials in self-owned germplasm resources as test seeds, and planting 30 rows and 5 m rows of test seeds in each test seed; using other germplasm resources as a tested system, planting 1 row of each material, configuring test cross combinations by adopting NCII genetic mating design, and 3 ears of each combination;

step 1.2: planting the test cross combinations in the step 1.1 according to a dot matrix design, wherein the row length is 5 meters, the row area is 2, the 3 times of repetition are carried out, the yield is calculated by harvesting in the whole area, and the special combining ability of each combination is calculated;

step 1.3: dividing the existing germplasm resources into two groups according to the fact that the germplasm resources are divided into a father group (group B) with the Special Combining Ability (SCA) Ts0 of female parent test seeds and are divided into a mother group (group A) with the Special Combining Ability (SCA) Ts0 of male parent test seeds;

step 2, the combination of the inbred line selection population and the selection of the offspring: in each corn growing season, the selected line group is prepared by homogeneous germplasm resources, generally 10-20 selected line groups are prepared in one corn growing season, the number of the selected line groups can be adjusted according to the conditions of manpower and material resources, the selection standard is improved in S1-S3 generations, and the combinations with obvious defects of lodging, grain shortage, stem rot and ear grain rot are eliminated as soon as possible; when the inbred lines of the S5-S8 generations tend to be stable, the spinning period is continuously investigated in 2-3 seasons, the inbred lines with the spinning period more than 5 days later than the parents of the inbred lines are eliminated, other selections are carried out according to breeding targets, and a stable inbred line group with excellent comprehensive properties, good resistance and no obvious defects is formed through 6-10 generations of inbred selection;

step 3, testing and matching the stable inbred line non-font:

step 3.1, establishing an isolation region: determining the number of the isolation regions according to the number of the test seeds, wherein several test seeds exist, namely, several isolation regions are established, and only one test seed is planted in each isolation region; the isolation area is established in two forms of time isolation and space isolation, wherein the time isolation is 15 days per sowing period, and the space isolation is more than 500 meters;

step 3.2, carrying out test design according to the number of the tested systems and the isolation region plots: designing a non-font planting picture, planting 3 rows of test seeds, wherein the length of the test seeds is the same as the length of the isolation region, the row spacing is 60cm, and the planting spacing is 20 cm; the tested lines are vertically planted on two sides of the test seeds, 1 line is planted on each tested line, the distance between each tested line and the test seeds is 20cm, the line length is 100cm, the line spacing is 60cm, and the plant spacing is 20 cm;

step 3.3, determining the seeding time: comparing the spinning period result of the tested series S5-S8 generation survey with the test seed powder scattering period to determine the sowing period; if the consistency of the spinning period of the tested line is better and is matched with the powder scattering period of the test seeds, the seeds can be sowed at the same time; the matching degree with the test seed powder scattering period is not good, and the test seeds need to be sowed in a staggered period, so that the spinning period of the tested line is ensured to be 2-3 days earlier than the test seed powder scattering period as the respective suitable sowing period;

step 3.4, emasculation of the tested line: after the large bell mouth period, observing the growth and development process of the test seeds and the tested line, judging the meeting degree of the test seed pollination period and the tested line pollination period, and estimating that when the test line pollination period is earlier than or equal to the test seed pollination period, the top ends of the male spikes of the tested line are exposed out of flag leaves, and the stem of the male spikes can be touched to be the emasculation proper period; until all the tested lines are emasculated;

step 3.5, artificial supplementary pollination: the test pollen quantity is large, auxiliary pollination is not needed generally, if the test pollen quantity is insufficient, artificial auxiliary pollination can be performed, and only one time of walking between test species in the morning and afternoon every day in the pollen scattering period is needed;

step 3.6, cutting off the test seeds in time; after the test seeds are pollinated, the test seeds are cut off in time;

step 3.7, timely harvesting: harvesting in time when the seed milk lines disappear, and individually bagging each tested line, and writing a name card;

step 4, determining the combining ability of the hybridization combination and identifying the strong dominant combination:

step 4.1, determining and applying hybridization combination combining ability: 20000-plus 30000 parts of hybrid combination seeds obtained by the test cross of the non-font test formula are planted according to the lattice design, 5 m of row length, 2 rows of areas, 2 times of repetition, and the yield is calculated by harvesting and counting in the whole area, and the general combining ability of the tested line and the special combining ability of the hybrid combination are calculated; for the common inbred lines with good combining ability, a new round of line selection and combination configuration can be carried out, so that recurrent selection of the inbred lines is realized, excellent allele polymerization is gradually improved, and the common excellent inbred lines with high combining ability are created;

step 4.2, seed production of the strong-superiority combination: in subsequent tests, including multipoint identification, regional tests and production tests, small-scale seed production needs to be carried out on the strong-advantage combination, and the non-font design can be continuously used according to the selected combination condition, so that simple seed production of hybrid seeds is realized.

2. The method for efficiently and rapidly detecting the combining ability of the maize inbred line according to claim 1, which is characterized by comprising the following steps: in the step 1.1, female parent materials are set to be Zheng 58 and PH6WC, and male parent materials are set to be Chang 7-2 and PH4 CV.

3. The method for efficiently and rapidly detecting the combining ability of the maize inbred line according to claim 1, which is characterized by comprising the following steps: in step 1.2, the specific combining ability of each combination is calculated according to the following formula:

S_ij＝X_ij-T_i/m-T_j/f+T/mf

wherein: s_ijThe specific combining ability of the tested system i and the test species j is shown;

X_ijthe yield of the combination of the tested series i and the test species j is obtained;

T_ithe m is the average value of the combined yield of the tested line i and all tested combinations;

T_jthe/f is the average value of the combined yield of all tested systems and the test species j;

t/mf is the mean of the yields of all combinations.

4. The method for efficiently and rapidly detecting the combining ability of the maize inbred line according to claim 1, which is characterized by comprising the following steps: in the step 3.2, for example, 500 tested systems are used, and the length of the isolation region is only required to be more than 150 meters, so that the test can be performed by the group of tests; if one group is not enough to arrange all the tested lines, repeating the operation; if the protected area needs to be planted, 4 test seeds in the peripheral seeds are used as the protected area.

5. The method for efficiently and rapidly detecting the combining ability of the maize inbred line according to claim 1, which is characterized by comprising the following steps: in the step 3.3, if the consistency of the spinning periods of the tested lines is not good and the spinning interval is less than 7 days, dividing the test seeds into a 2 nd period, a 1 st period in the 2 th line and a 2 nd period after 5-7 days in the middle 1 line; if the spinning period interval is more than 7 days, different groups of tests are not recommended.

6. The method for efficiently and rapidly detecting the combining ability of the maize inbred line according to claim 1, which is characterized by comprising the following steps: when the spinning period of the tested line in the step 3.4 is later than the test seed pollen scattering period, the emasculation time is properly advanced; the emasculation time is controlled from nine am to five pm every day once a day until the emasculation of all the tested lines is completed.

7. The method for efficiently and rapidly detecting the combining ability of the maize inbred line according to claim 1, which is characterized by comprising the following steps: in the step 4.1, for the hybridization combination with high special combining ability, a multipoint identification test is carried out, and generally the selected combination is not more than 200 parts.

Technical Field

The invention relates to the technical field of crop breeding, in particular to a method for efficiently and quickly detecting the combining ability of a maize inbred line.

Background

The rapid determination and utilization of the combining ability of the maize inbred line are one of the most critical links in maize breeding, a breeding team in China generally combines 20000 + 30000 hybrid combinations every year, the pollination task is very difficult, a large amount of manpower is required for support, but along with the gradual advance of urbanization in recent years, rural labor force is gradually transferred, the employment of workers by scientific research units is more and more difficult, and a proper method is urgently needed to be found, so that the labor input is reduced, and the efficiency is improved.

Disclosure of Invention

In order to overcome the above-mentioned drawbacks of the prior art, embodiments of the present invention provide a method for efficiently and rapidly detecting the combining ability of a maize inbred line, so as to solve the above-mentioned technical problems.

In order to achieve the purpose, the invention provides the following technical scheme: a high-efficiency and rapid detection method for the combining ability of a maize inbred line comprises the following specific detection steps:

step 1, creating AB grouping of basic materials by inbred lines: classifying the germplasm resources according to a parent group (A group) and a father group (B group);

step 1.1: selecting two typical female parent materials and two typical male parent materials in self-owned germplasm resources as test seeds, and planting 30 rows and 5 m rows of test seeds in each test seed; other germplasm resources are used as a tested system, 1 row of each material is planted, test cross combinations are configured by adopting NCII genetic mating design, and 3 ears of each combination ensure that seeds can be tested in the next step;

step 1.2: planting the test cross combinations in the step 1.1 according to a dot matrix design, wherein the row length is 5 meters, the row area is 2, the 3 times of repetition are carried out, the yield is calculated by harvesting in the whole area, and the special combining ability of each combination is calculated;

step 1.3: dividing the existing germplasm resources into two groups according to the fact that the germplasm resources are divided into a father group (group B) with the Special Combining Ability (SCA) Ts0 of female parent test seeds and are divided into a mother group (group A) with the Special Combining Ability (SCA) Ts0 of male parent test seeds;

step 2, the combination of the inbred line selection population and the selection of the offspring: in each corn growing season, homogeneous germplasm resources are prepared when a selected line group is prepared, such as a group A selected line group prepared in summer of 2019 and a group B selected line group prepared in winter of 2019; generally, 10-20 selected line groups are allocated in one corn growing season, the number of the selected line groups can be adjusted according to the conditions of manpower and material resources, the selection standards of S1-S3 generations are improved, and the selected line groups with obvious defects of lodging, grain lack, stem rot and ear grain rot are eliminated as early as possible; when the inbred lines of the S5-S8 generations tend to be stable, the spinning period is continuously investigated in 2-3 seasons, the inbred lines with the spinning period more than 5 days later than the parents of the inbred lines are eliminated, other selections are carried out according to breeding targets, and stable inbred line groups with excellent comprehensive properties, good resistance and no obvious defects are formed through 6-10 generations of inbred selection, wherein the stable inbred line groups generally comprise 500-1000 selected inbred lines to be tested;

step 3, testing and matching the stable inbred line non-font:

step 3.1, establishing an isolation region: determining the number of the isolation regions according to the number of the test seeds, wherein several test seeds exist, namely, several isolation regions are established, and only one test seed is planted in each isolation region; the isolation area is established in two forms of time isolation and space isolation, wherein the time isolation is 15 days per sowing period, and the space isolation is more than 500 meters; for example: selecting 12 test seeds in the balanced water in 2020, namely dividing the test seeds into three sowing periods of 4 months and 30 days, 5 months and 15 days and 5 months and 31 days, and establishing 4 isolation regions at each sowing period by spatial separation;

step 3.2, carrying out test design according to the number of the tested systems and the isolation region plots: designing a non-font planting diagram according to the diagram shown in figure 1, wherein three horizontal lines are test seeds, a vertical line is a tested seed on two sides of the test seeds, the test seeds are planted in 3 rows, the length of the test seeds is the same as the length of the isolation region, the row spacing is 60cm, and the plant spacing is 20 cm; the tested lines are vertically planted on two sides of the test seeds, 1 line is planted on each tested line, the distance between each tested line and the test seeds is 20cm, the line length is 100cm, the line spacing is 60cm, and the plant spacing is 20 cm;

step 3.3, determining the seeding time: comparing the spinning period result of the tested series S5-S8 generation survey with the test seed powder scattering period to determine the sowing period; if the consistency of the spinning period of the tested line is better and is matched with the powder scattering period of the test seeds, the seeds can be sowed at the same time; the matching degree with the test seed powder scattering period is not good, and the test seeds need to be sowed in a staggered period, so that the spinning period of the tested line is ensured to be 2-3 days earlier than the test seed powder scattering period as the respective suitable sowing period;

step 3.4, emasculation of the tested line: after the large bell mouth period, observing the growth and development process of the test seeds and the tested line, judging the meeting degree of the test seed pollination period and the tested line pollination period, and estimating that when the test line pollination period is earlier than or equal to the test seed pollination period, the top ends of the male spikes of the tested line are exposed out of flag leaves, and the stem of the male spikes can be touched to be the emasculation proper period; predicting that the later the spinning period is, the earlier the emasculation time is, so as to reduce the nutrient consumption of the upper leaves and the tassels, promote the nutrient supply to the female ears, enable the female ears to spin early but not to completely unfold earlier than the fallen 5 leaves until the emasculation of all the tested lines is completed;

step 3.5, artificial supplementary pollination: the test pollen quantity is large, auxiliary pollination is not needed generally, if the test pollen quantity is insufficient, artificial auxiliary pollination can be performed, and only one time of walking between test species in the morning and afternoon every day in the pollen scattering period is needed;

step 3.6, cutting off the test seeds in time; after the test seeds are pollinated, the test seeds are cut off in time so as to increase ventilation and light transmission, reduce soil and fertilizer water loss and improve the tying rate of the tested knot;

step 3.7, timely harvesting: harvesting in time when the seed milk lines disappear, and individually bagging each tested line, and writing a name card;

step 4, determining the combining ability of the hybridization combination and identifying the strong dominant combination:

step 4.1, determining and applying hybridization combination combining ability: 20000-plus 30000 parts of hybrid combination seeds obtained by the test cross of the non-font test formula are planted according to the lattice design, 5 m of row length, 2 rows of areas, 2 times of repetition, and the yield is calculated by harvesting and counting in the whole area, and the general combining ability of the tested line and the special combining ability of the hybrid combination are calculated; for the common inbred lines with good combining ability, a new round of line selection and combination configuration can be carried out, so that recurrent selection of the inbred lines is realized, excellent allele polymerization is gradually improved, and the common excellent inbred lines with high combining ability are created;

step 4.2, seed production of the strong-superiority combination: in subsequent tests, including multipoint identification, regional tests and production tests, the strong dominant combination needs to be subjected to small-scale seed production, the non-font design can be continuously used according to the selected combination condition, the simple seed production of hybrid seeds is realized, the yield and purity of the seed production can be well ensured, and the investment of manpower and material resources is reduced.

In a preferred embodiment, the maternal material is set to Zheng 58 and PH6WC and the paternal material is set to Chang 7-2 and PH4CV in step 1.1.

In a preferred embodiment, in step 1.2, the specific mating force of each combination is calculated according to the following formula:

S_ij＝X_ij-T_i/m-T_j/f+T/mf

wherein: s_ijThe specific combining ability of the tested system i and the test species j is shown;

X_ijthe yield of the combination of the tested series i and the test species j is obtained;

T_ithe m is the average value of the combined yield of the tested line i and all tested combinations;

T_jthe/f is the average value of the combined yield of all tested systems and the test species j;

t/mf is the mean of the yields of all combinations.

In a preferred embodiment, taking 500 tested samples as an example in step 3.2, the length of the isolation region is only required to exceed 150 meters, and the above-mentioned group of tests is only required; if one group is not enough to arrange all the tested lines, repeating the operation; if the protected area needs to be planted, 4 test seeds in the peripheral seeds are used as the protected area.

In a preferred embodiment, in step 3.3, if the measured laying period consistency is not good and the laying interval is less than 7 days, dividing the test seeds into 2 periods, 2 lines 1 period, and 5-7 days later than 2 periods in the middle 1 line; if the spinning period interval is more than 7 days, different groups of tests are not recommended.

In a preferred embodiment, when the spinning period of the tested line in the step 3.4 is later than the test seed pollen dispersing period, the castration time is appropriately advanced; the emasculation time is controlled from nine am to five pm every day once a day until the emasculation of all the tested lines is completed.

In a preferred embodiment, said step 4.1 is performed on a hybridization combination with high specific combining ability, and the selected combination is generally not more than 200 parts.

The invention has the technical effects and advantages that:

according to the invention, a non-character testing and matching test design is created, so that the labor investment is greatly reduced, and the labor risk is reduced.

Drawings

FIG. 1 is a test planting chart of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a high-efficiency and rapid detection method for the combining ability of a maize inbred line, which is shown in figure 1 and comprises the following specific detection steps:

step 1, creating AB grouping of basic materials by inbred lines: classifying the germplasm resources according to a parent group (A group) and a father group (B group);

step 1.1: selecting two female parent materials (Zheng 58 and PH6WC) and two male parent materials (Chang 7-2 and PH4CV) which are typical in self-owned germplasm resources as test seeds, and planting 30 rows and 5 m rows in each test seed; other germplasm resources are used as a tested system, 1 row of each material is planted, test cross combinations are configured by adopting NCII genetic mating design, and 3 ears of each combination ensure that seeds can be tested in the next step;

step 1.2: planting the test cross combinations in the step 1.1 according to a dot matrix design, wherein the row length is 5 meters, the row area is 2, the 3 times of repetition are carried out, the yield is calculated according to the harvest in the whole area, and the special combining ability of each combination is calculated according to the following formula:

S_ij＝X_ij-T_i/m-T_j/f+T/mf

wherein: s_ijThe specific combining ability of the tested system i and the test species j is shown;

X_ijthe yield of the combination of the tested series i and the test species j is obtained;

T_ithe m is the average value of the combined yield of the tested line i and all tested combinations;

T_jthe/f is the average value of the combined yield of all tested systems and the test species j;

t/mf is the average value of the yield of all combinations;

step 1.3: dividing the existing germplasm resources into two groups according to the fact that the germplasm resources are divided into a father group (group B) with the Special Combining Ability (SCA) Ts0 of female parent test seeds and are divided into a mother group (group A) with the Special Combining Ability (SCA) Ts0 of male parent test seeds;

step 2, the combination of the inbred line selection population and the selection of the offspring: in each corn growing season, homogeneous germplasm resources are prepared when a selected line group is prepared, such as a group A selected line group prepared in summer of 2019 and a group B selected line group prepared in winter of 2019; generally, 10-20 selected line groups are allocated in one corn growing season, the number of the selected line groups can be adjusted according to the conditions of manpower and material resources, the selection standards of S1-S3 generations are improved, and the selected line groups with obvious defects of lodging, grain lack, stem rot and ear grain rot are eliminated as early as possible; when the inbred lines of the S5-S8 generations tend to be stable, the spinning period is continuously investigated in 2-3 seasons, the inbred lines with the spinning period more than 5 days later than the parents of the inbred lines are eliminated, other selections are carried out according to breeding targets, and stable inbred line groups with excellent comprehensive properties, good resistance and no obvious defects are formed through 6-10 generations of inbred selection, wherein the stable inbred line groups generally comprise 500-1000 selected inbred lines to be tested;

step 3, testing and matching the stable inbred line non-font: at present, the conventional method comprises planting 2 rows of regions and 5 m row length in each of 500 inbred lines, wherein 1 row is inbred and 1 row is tested and matched; testing 10-15 seeds, wherein the seeds are planted for 30-50 lines and 5 m lines according to different pollen amounts of the seeds; after the female ear of the tested line appears, sheathing a sheepskin paper bag to prevent from receiving external pollen, after the tested seed is tested for pollen scattering, taking the pollen of the sheepskin paper bag, pollinating the tested line one by one, and pollinating about 2 ears generally; the method generally needs 3-5 people, is finished in 7-10 days, and consumes more manpower; in addition, the temperature is about 35 ℃ in a pollination season, the air humidity is high, the stuffiness is difficult to endure, the heatstroke phenomenon often occurs, and the current agricultural test workers are generally older and have greater risks;

in order to change the situation, a non-character testing and matching test design is innovated through exploration and research, so that the labor investment is greatly reduced, and the labor risk is reduced; the specific method comprises the following steps:

step 3.1, establishing an isolation region: determining the number of the isolation regions according to the number of the test seeds, wherein several test seeds exist, namely, several isolation regions are established, and only one test seed is planted in each isolation region; the isolation area is established in two forms of time isolation and space isolation, wherein the time isolation is 15 days per sowing period, and the space isolation is more than 500 meters; for example: selecting 12 test seeds in the balanced water in 2020, namely dividing the test seeds into three sowing periods of 4 months and 30 days, 5 months and 15 days and 5 months and 31 days, and establishing 4 isolation regions at each sowing period by spatial separation;

step 3.2, carrying out test design according to the number of the tested systems and the isolation region plots: designing a non-font planting diagram according to the diagram shown in figure 1, wherein three horizontal lines are test seeds, a vertical line is a tested seed on two sides of the test seeds, the test seeds are planted in 3 rows, the length of the test seeds is the same as the length of the isolation region, the row spacing is 60cm, and the plant spacing is 20 cm; the tested lines are vertically planted on two sides of the test seeds, 1 line is planted on each tested line, the distance between each tested line and the test seeds is 20cm, the line length is 100cm, the line spacing is 60cm, and the plant spacing is 20 cm; taking 500 tested samples as an example, the length of the isolation region is only required to exceed 150 meters, and the test can be carried out by the group; if one group is not enough to arrange all the tested lines, repeating the operation; if the protected area needs to be planted, 4 test seeds in the peripheral seeds are used as the protected area;

step 3.3, determining the seeding time: comparing the spinning period result of the tested series S5-S8 generation survey with the test seed powder scattering period to determine the sowing period; if the consistency of the spinning period of the tested line is better and is matched with the powder scattering period of the test seeds, the seeds can be sowed at the same time; the matching degree with the test seed powder scattering period is not good, the test seeds are sowed in a staggered period, the fact that the spinning period of the tested line is 2-3 days earlier than the test seed powder scattering period is guaranteed to be the respectively suitable sowing period, if the spinning period of the tested line is not good in consistency, and the spinning interval is less than 7 days, the test seeds are divided into 2 periods, 2 periods are carried out at the side of 1 period, and the 2 periods are carried out after 5-7 days in the middle of 1 period; if the interval of the spinning period is more than 7 days, different groups of tests are not recommended;

step 3.4, emasculation of the tested line: observing the growth and development processes of the test seeds and the tested line after the large bell mouth period, judging the meeting degree of the test seed pollination period and the tested line pollination period, estimating that when the test line pollination period is earlier than or equal to the test seed pollination period, the male spike of the tested line has a certain top end to expose flag leaves, and the stem of the spike can be touched to be a castration suitable period, and when the test line pollination period is later than the test seed pollination period, suitably advancing the castration time; predicting that the later the spinning period is, the earlier the emasculation time is, so as to reduce the nutrient consumption of the upper leaves and the tassels, promote the nutrient supply to the female ears, enable the female ears to spin early, but not to fully unfold before the fallen 5 leaves until the emasculation of all the tested lines is completed, mastering the emasculation time every day from nine am to five pm, and once every day until the emasculation of all the tested lines is completed;

step 3.5, artificial supplementary pollination: the test pollen quantity is large, auxiliary pollination is not needed generally, if the test pollen quantity is insufficient, artificial auxiliary pollination can be performed, and only one time of walking between test species in the morning and afternoon every day in the pollen scattering period is needed;

step 3.6, cutting off the test seeds in time; after the test seeds are pollinated, the test seeds are cut off in time so as to increase ventilation and light transmission, reduce soil and fertilizer water loss and improve the tying rate of the tested knot;

step 3.7, timely harvesting: harvesting in time when the seed milk lines disappear, and individually bagging each tested line, and writing a name card;

step 4, determining the combining ability of the hybridization combination and identifying the strong dominant combination:

step 4.1, determining and applying hybridization combination combining ability: 20000-plus 30000 parts of hybrid combination seeds obtained by the test cross of the non-font test formula are planted according to the lattice design, 5 m of row length, 2 rows of areas, 2 times of repetition, and the yield is calculated by harvesting and counting in the whole area, and the general combining ability of the tested line and the special combining ability of the hybrid combination are calculated; for the general inbred line with good combining ability, a new round of line selection combination configuration can be carried out, so that recurrent selection of the inbred line is realized, excellent allele polymerization is gradually improved, the general excellent inbred line with high combining ability is created, for the hybrid combination with high special combining ability, a multipoint identification test is carried out, and the general selected combination is not higher than 200 parts;

step 4.2, seed production of the strong-superiority combination: in subsequent tests, including multipoint identification, regional tests and production tests, the strong dominant combination needs to be subjected to small-scale seed production, the non-font design can be continuously used according to the selected combination condition, the simple seed production of hybrid seeds is realized, the yield and purity of the seed production can be well ensured, and the investment of manpower and material resources is reduced.

The points to be finally explained are: first, in the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounted," "connected," and "connected" should be understood broadly, and may be a mechanical connection or an electrical connection, or a communication between two elements, and may be a direct connection, and "upper," "lower," "left," and "right" are only used to indicate a relative positional relationship, and when the absolute position of the object to be described is changed, the relative positional relationship may be changed;

secondly, the method comprises the following steps: in the drawings of the disclosed embodiments of the invention, only the structures related to the disclosed embodiments are referred to, other structures can refer to common designs, and the same embodiment and different embodiments of the invention can be combined with each other without conflict;

and finally: the above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention are intended to be included in the scope of the present invention.