A method for cultivating drought-resistant maize and its application

Abstract

The invention discloses a method for cultivating drought-resistant corn and its application, and relates to the field of biological breeding technology. The method comprises the following steps: after ly8406 is hybridized with PH6WC, self-pollination is performed to obtain a self-fertile line Z39-1; after PH4CV is hybridized with LY1359, a DH (Double Haploid) line DHZ62-3 (the double haploid obtained by haploid doubling is a DH line, also known as a DH population) is produced after induction by haploid induction technology and natural doubling; after hybridization of the self-fertile line Z39-1 and the DH line DHZ62-3, a new drought-resistant corn variety Longdan 639 is obtained. The method can be used to cultivate a drought-resistant corn variety, which is suitable for planting in dry land. After testing, the average yield per mu can reach more than 1,000 kilograms. The method of the present invention provides technical support for the creation of drought-resistant excellent corn germplasm resources, and has important agricultural promotion and application value.

Description

Technical Field

[0001] The invention relates to the technical field of biological breeding, and in particular to a method for cultivating drought-resistant corn and application thereof. Background Art

[0002] Drought is a common natural disaster, which is affected by many factors such as precipitation, temperature, light and soil conditions. In recent years, due to abnormal changes in the global climate and frequent occurrence of extreme high temperatures, drought has become a frequent abiotic stress. Drought may cause major problems in global food security. Analyzing the mechanism of plant response to drought, cultivating new varieties of drought-tolerant crops, and increasing crop yields have become major issues that scientists need to solve urgently.

[0003] Corn is an important food crop in my country, as well as an important feed and industrial raw material. During its growth and development, it is sensitive to various environmental stresses, such as drought, salt, high temperature, low temperature, and pests and diseases, which leads to a significant decline in corn yield and quality. Drought stress can affect the normal development and morphology of plants, thereby inhibiting their growth and reducing their yield. According to reports, in the past 50 years, yield losses caused by drought stress accounted for 67% of the total grain losses. Although corn is a dryland crop, it has a strong demand for water and is sensitive to drought at multiple growth stages. In recent years, water resources in the main corn-producing areas in northern my country have become increasingly scarce, and irrigation in the hilly and mountainous corn-producing areas in the south has been inconvenient. Corn production has been severely affected by drought. Therefore, drought has become one of the main abiotic stresses that currently restrict corn planting. However, my country currently lacks excellent corn varieties with good drought tolerance and can be promoted on a large scale. Therefore, it is urgent to create drought-resistant and excellent corn germplasm resources. Summary of the invention

[0004] The purpose of the present invention is to provide a method for cultivating drought-resistant corn and its application to solve the problems existing in the above-mentioned prior art. The method provides technical support for creating drought-resistant high-quality corn germplasm resources and has important agricultural promotion and application value.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for cultivating drought-resistant corn, comprising the following steps:

[0007] After crossing ly8406 with PH6WC and self-pollination, the self-fertile line Z39-1 was obtained;

[0008] After crossing PH4CV with LY1359, the DH line DHZ62-3 was generated by haploid induction and doubling;

[0009] The drought-resistant corn variety Longdan 639 was obtained by hybridizing the self-fertile line Z39-1 and the DH line DHZ62-3.

[0010] Furthermore, hybridization is performed using the self-fertile line Z39-1 as the female parent and the DH line DHZ62-3 as the male parent.

[0011] The present invention adopts general field small-scale seed production hybridization, and the main work in the early stage of pollination is to cover the female ears. Before the female ears of the female parent do not extract the filaments, the female ears are covered with a new sulfuric acid paper bag to prevent the female ears from growing and spitting out the filaments and contacting with other male pollens to complete fertilization. Therefore, the female ears of the female parent should be strictly bagged, and the female ears develop and grow, and gradually spit out the filaments in the sulfuric acid paper bag, and the filaments are pollution-free. Correctly select the first ear, require that the female ears cannot be too small, and the female ears that have already spit out silk cannot be covered. When bagging, one side of the bag is close to the leaf sheath, and the other side is close to the stem. If an inbred line is encountered in which the female ears do not come out of the leaf sheath or part of the sheath just spit out silk, the leaf sheath can be peeled off and bagged. When the husk of the male ear is opened and the anther is exposed, the male ear can be covered. On the afternoon before hybridization pollination, all the tassels for collecting pollen are also covered with larger sulfuric acid paper bags. When covering the tassels, first open the paper bag, then hold the paper bag with one hand and the internode of the tassel with the other hand, and completely cover the tassel with the paper bag, then fold the paper bag around the stem, and use a pin to pierce the stem to fix the paper bag, so as to prevent other pollen from falling and pollen impurity from causing insufficient purity of seeds after hybridization. Between 9 and 11 a.m. the next day, collect pollen during the peak pollen season, collect all the pollen in the sulfuric acid paper bag together, sift through a sieve, remove the anthers, collect a large amount of pollen, and evenly sprinkle the male parent's pollen on the filaments of the female parent's bag (during the pollination process, first gently remove the sulfuric acid paper bag. Generally, during hybridization, if the female ear filaments in the bag are too long, use scissors or other tools to uniformly cut off the longer filaments, leaving 1 to 2 cm "brush-like filaments", and quickly and evenly shake the pollen onto the female ear filaments of the female parent). After the pollen comes into contact with the filaments, quickly change to sulfuric acid paper bags of different colors to cover the pollinated female ears, gradually complete fertilization and development, and wait for the seeds to grow and mature before harvesting.

[0012] Large-scale seed production generally adopts a 50m field isolation belt around the field. The female parent is planted in 6-7 rows and the male parent is planted in 1 row with an interval ratio. When the male spike of the female parent has not yet stretched out, the male parent begins to emerge from the bracts. Then the flowering period of the male parent is coordinated with the silking period of the female parent. The pollen of the male parent is scattered by the wind on the silk of the woody female spike to complete fertilization. Therefore, large-scale seed production adopts an open "natural pollination" method to complete hybridization.

[0013] Furthermore, the traits of the self-fertile line Z39-1 include: medium green leaf color of seedlings, light purple leaf sheaths, green leaf margins, and semi-compact plant type; average plant height of about 248 cm, average ear height of about 73 cm, 2 to 4 primary branches of the male spike, 19 leaves on mature plants, yellow filaments, purple anthers, conical ears, ear length of about 17.0 cm, ear thickness of about 4.8 cm, axis thickness of about 2.5 cm, 18 ear rows, yellow and semi-hard grains, and red ear axes.

[0014] Furthermore, the traits of the DH series DHZ62-3 include: a semi-compact plant type, an average plant height of 198 cm, an average ear height of 65 cm, 19 leaves on mature plants, 3 to 5 primary branches on the male spike, medium green leaf color on seedlings, green leaf margins, light purple leaf sheaths, pink filaments, yellow anthers, conical ear, ear length of about 14.3 cm, 14 rows of ears, ear thickness of about 4.4 cm, axis thickness of about 2.6 cm, yellow, horse-tooth-shaped grains, and red ear axis.

[0015] Furthermore, the characteristics of the drought-resistant corn variety Longdan 639 are: green leaf sheaths of seedlings, green leaves, and green leaf margins; semi-compact plant type, average plant height 290 cm, ear height 102 cm, and 19 leaves on mature plants; green stem base, light purple anthers, purple husks; yellow filaments, cylindrical ears, average ear length 19.6 cm, 16 rows of ears, an average number of 35.8 grains per row, red cobs, yellow grains, semi-dent shape, and 100-grain weight 41.9 g.

[0016] Furthermore, after the ly8406 was hybridized with the PH6WC, the self-fertile line Z39-1 was obtained after 7 generations of self-pollination.

[0017] The present invention also provides an application of the drought-resistant corn cultivated according to the above method in dryland agricultural planting.

[0018] The present invention discloses the following technical effects:

[0019] The present invention develops a method for cultivating drought-resistant corn, and the drought-resistant corn variety Longdan 639 can be cultivated by the method. Longdan 639 is about 140 days from emergence to maturity, the seedling leaf sheath is green, the leaf blade is green, and the leaf margin is green; the plant type is semi-compact, the average plant height is 290cm, the ear height is 102cm, and the number of leaves of the mature plant is 19; the stem base is green, the anther is light purple, and the husk is purple; the filament is yellow, the ear is cylindrical, the average ear length is 19.6cm, the number of ear rows is 16, the average number of rows is 35.8, the ear axis is red, the grain is yellow, semi-horse dent, and the hundred-grain weight is 41.9g. Longdan 639 is suitable for planting in dry land. After testing, the average yield per mu can reach more than 1,000 kilograms. The method of the present invention provides technical support for creating drought-resistant excellent corn germplasm resources, and has important agricultural promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is the breeding flow chart of Longdan 639;

[0022] Figure 2 The following is a comparison of the characteristics of Longdan 639 and Xianyu 335; A is a seedling; B is a male ear; C is a female ear; D is a fruit ear; E is a plant; in AE, the left side is Longdan 639, and the right side is Xianyu 335;

[0023] Figure 3 These are the ears of Longdan 639 and Xianyu 335 under normal irrigation and limited irrigation (70% of the normal irrigation amount). DETAILED DESCRIPTION

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0026] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0027] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0028] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0029] The corn basic materials ly8406, PH6WC, PH4CV and LY1359 used in the following examples are from the germplasm resource bank of Gansu Academy of Agricultural Sciences; the present invention promises that the above corn basic materials will be open to the public 20 years from the filing date of the present invention.

[0030] Xianyu 335 is a common corn variety approved by the state in 2006, with the approval number: Guoshenyu 2004017.

[0031] Example 1

[0032] The research and development team of this invention based its research on the introduction, innovation and utilization of excellent germplasm in haploid breeding, adopted a breeding approach of "large-scale, multi-location and sustainability", and formed a high-efficiency corn breeding technology system of "excellent germplasm materials + high-efficiency selection methods (high density, multi-location, strong stress, strict selection) + new combination and multi-environment testing", and bred the drought-resistant, dense-resistant and mechanized-harvesting variety Longdan 639.

[0033] 1. Breeding process and variety characteristics

[0034] like Figure 1 As shown, the present invention uses Z39-1 as the female parent and DHZ62-3 as the male parent to hybridize and obtain a new drought-resistant corn variety named Longdan 639. The specific breeding process is described in detail as follows:

[0035] The self-fertile line was obtained by self-pollination selection of ly8406 and PH6WC in Zhangye and Hainan for 7 consecutive generations. It was named Z39-1. The specific process is as follows:

[0036] First, we used large populations, high density, and multiple locations to conduct strict selection under limited irrigation (70% of normal irrigation) and low nitrogen stress (70% of normal urea application). In 2015, we selected 90,000 plants / hm2 at the Zhangye breeding base. 2 Density Planting F 2There are about 3,000 plants in the population. Individual plants are selected according to the target traits of compact plant type, strong growth, strong stem toughness, and fewer male spike branches. When harvesting, excellent plants with good resistance and good spike traits are selected. When testing indoors, 86 spikes with 16-20 rows, neat arrangement, high 100-grain weight, and good capping are selected. In winter, the selected spikes are planted at the Hainan breeding base with the same density and the same limited irrigation conditions. Two rows are selected for each spike, with a row length of 4m, and 65 spikes are harvested (F 3 ) In 2016, the planting density was increased to 105,000 plants / hm2. 2 Density planting, also in high-density, multi-location limited irrigation and low nitrogen stress environment, strict breeding, north-south shuttle breeding in Zhangye and Hainan, focus on the selection of good resistance, plant height but low ear position, tolerance to dense planting, other well-developed single plant harvest, especially under limited irrigation and low nitrogen stress conditions, screening out the excellent performance of the isolated population, after indoor testing, select the excellent single plant ear 50 (F 4 ), 35 bunches (F 5 ); In the spring of 2017, 25 ear rows were planted in a single row under the same density and stress environment at the Zhangye test site. The various traits of the ear rows tended to be stable, and the phenotypes were relatively uniform. The ear rows with excellent phenotypes were selected for combining ability determination. In winter, ear rows were planted at the same density in Hainan, and the combining ability of the test combinations was determined and analyzed; in 2018, cross-crossing was performed based on a single parent and other maternal or paternal inbred lines. According to the GCA (general combining ability) and SCA (special combining ability) calculation formulas, the GCA and SCA values ​​of the single parent were calculated based on the yield results of the test hybrid combination, and a single ear row with high combining ability was selected. At the Zhangye test base, 90,000 plants / hm2 were used. 2 The inbred line was selected and propagated with density retention rows and named Z39-1.

[0037] The characteristics of the self-bred line Z39-1 are as follows: the growth period is about 137 days; the leaf color of the seedling is medium green, the leaf sheath is light purple, the leaf edge is green, and the plant type is semi-compact; the average plant height is about 248cm, the average ear height is about 73cm, the number of primary branches of the male spike is 2 to 4, the number of leaves of the mature plant is 19 leaves, the filaments are yellow, the anthers are purple, the fruit spike is conical, the spike length is about 17.0cm, the spike diameter is about 4.8cm, the axis diameter is about 2.5cm, the number of spike rows is 18, the grains are yellow and semi-hard, and the spike axis is red; it is resistant to lodging and stem rot.

[0038] The basic material composed of PH4CV and LY1359 was 2 Haploid induction and doubling were performed in the next generation to produce an excellent DH (Double Haploid) line, named DHZ62-3 (the double haploid obtained by haploid doubling is the DH line, also known as the DH population).

[0039] The characteristics of DH series DHZ62-3 are as follows: the growth period is about 132 days; the plant type is semi-compact, the average plant height is 198cm, the average ear height is 65cm, the mature plant has 19 leaves, the male ear has 3 to 5 primary branches, the seedling leaves are medium green, the leaf margins are green, the leaf sheaths are light purple, the filaments are pink, the anthers are yellow, the ear is conical, the ear length is about 14.3cm, the number of ear rows is 14, the ear thickness is about 4.4cm, the axis thickness is about 2.6cm, the grains are yellow and horse-toothed, and the ear axis is red; it is highly resistant to lodging, and resistant to corn leaf blight and stem rot.

[0040] With Z39-1 as the female parent and DHZ62-3 as the male parent, after hybridization, the following F genes were obtained by screening. 1 The offspring is a drought-resistant corn variety named Longdan 639: the seedling leaf sheath is green, the leaves are green, and the leaf margins are green; the plant type is semi-compact, the plant height is 290 cm, the ear height is 102 cm, and the number of leaves on the mature plant is 19; the stem base is green, the anther is light purple, and the husk is purple; the filaments are yellow, the ear is cylindrical, the ear length is 19.6 cm, the number of ear rows is 16, the number of kernels per row is 35.8, the ear axis is red, the kernels are yellow and semi-dent, and the 100-kernel weight is 41.9 g (see Figure 2 Longdan 639 matures 2 to 3 days earlier than the control variety Xianyu 335 when planted in the same ecological environment.

[0041] The present invention adopts general field small-scale seed production hybridization, and the main work in the early stage of pollination is to cover the female ears. Before the female ears of the female parent do not extract the filaments, the female ears are covered with a new sulfuric acid paper bag to prevent the female ears from growing and spitting out the filaments and contacting with other male pollens to complete fertilization. Therefore, the female ears of the female parent should be strictly bagged, and the female ears develop and grow, and gradually spit out the filaments in the sulfuric acid paper bag, and the filaments are pollution-free. Correctly select the first ear, require that the female ears cannot be too small, and the female ears that have already spit out silk cannot be covered. When bagging, one side of the bag is close to the leaf sheath, and the other side is close to the stem. If an inbred line is encountered in which the female ears do not come out of the leaf sheath or part of the sheath just spit out silk, the leaf sheath can be peeled off and bagged. When the husk of the male ear is opened and the anther is exposed, the male ear can be covered. On the afternoon before hybridization pollination, all the tassels for collecting pollen are also covered with larger sulfuric acid paper bags. When covering the tassels, first open the paper bag, then hold the paper bag with one hand and the internode of the tassel with the other hand, and completely cover the tassel with the paper bag, then fold the paper bag around the stem, and use a pin to pierce the stem to fix the paper bag, so as to prevent other pollen from falling and pollen impurity from causing insufficient purity of seeds after hybridization. Between 9 and 11 a.m. the next day, collect pollen during the peak pollen season, collect all the pollen in the sulfuric acid paper bag together, sift through a sieve, remove the anthers, collect a large amount of pollen, and evenly sprinkle the male parent's pollen on the filaments of the female parent's bag (during the pollination process, first gently remove the sulfuric acid paper bag. Generally, during hybridization, if the female ear filaments in the bag are too long, use scissors or other tools to uniformly cut off the longer filaments, leaving 1 to 2 cm "brush-like filaments", and quickly and evenly shake the pollen onto the female ear filaments of the female parent). After the pollen comes into contact with the filaments, quickly change to sulfuric acid paper bags of different colors to cover the pollinated female ears, gradually complete fertilization and development, and wait for the seeds to grow and mature before harvesting.

[0042] Large-scale seed production generally adopts a 50m field isolation belt around the field. The female parent is planted in 6-7 rows and the male parent is planted in 1 row with an interval ratio. When the male spike of the female parent has not yet stretched out, the male parent begins to emerge from the bracts. Then the flowering period of the male parent is coordinated with the silking period of the female parent. The pollen of the male parent is scattered by the wind on the silk of the woody female spike to complete fertilization. Therefore, large-scale seed production adopts an open "natural pollination" method to complete hybridization.

[0043] 2. Output performance

[0044] Gansu Province is located at the intersection of the Qinghai-Tibet Plateau, the Inner Mongolia Plateau and the Loess Plateau. It has a unique geographical location and topography, complex and diverse climate types, and more than two-thirds of the cultivated land is dry land. The present invention conducts a planting test of Longdan 639 in a dry land test field in Gansu Province, which is described in detail as follows:

[0045] Longdan 639 participated in the regional corn variety trial in Gansu Province from 2020 to 2021 (with Xianyu 335 as the control), and the test results are shown in Table 1. The results showed that the average yield of Longdan 639 was 1107.4 kg per mu in 2020, an increase of 6.0% over the control Xianyu 335; the average yield of Longdan 639 was 1073.8 kg per mu in 2021, an increase of 5.6% over the control Xianyu 335. The average yield of Longdan 639 in two years was 1090.6 kg per mu, an increase of 5.8% over the control Xianyu 335.

[0046] Longdan 639 participated in the production test in 2022 (with Xianyu 335 as the control), and the test results are shown in Table 2. The results show that the average yield of Longdan 639 in the 2022 production test was 1000.8 kg per mu, an increase of 6.4% over the control Xianyu 335. Under normal irrigation and limited irrigation conditions, Longdan 639 increased its yield over the control Xianyu 335, especially under limited irrigation conditions, the ear length of Longdan 639 was longer than the control, and the bald tip length was shorter than the control ( Figure 3 ).

[0047] Table 1 Yield performance of Longdan 639 in regional trials

[0048]

[0049] Table 2 Yield performance of Longdan 639 production trial (2022)

[0050]

[0051] 3. Disease resistance

[0052] According to the inoculation and identification by the Institute of Plant Protection, Gansu Academy of Agricultural Sciences in 2021-2022, Longdan 639 is resistant to Fusarium stem rot (R, diseased plant rate is 10.0%), highly susceptible to Fusarium ear rot (HS, average disease level is 7.8), moderately resistant to head smut (MR, diseased plant rate is 8.3%), and susceptible to large leaf spot (S, disease level is 7).

[0053] 4. Quality

[0054] According to the inspection by the Agricultural Testing Center of Gansu Academy of Agricultural Sciences, the bulk density of Longdan 639 is 728g / L, the protein (dry basis) is 8.71g / 100g, the crude fat (dry basis) is 3.69%, the crude starch (dry basis) is 76.67%, and the lysine (dry basis) is 0.297%.

[0055] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for cultivating drought-resistant corn, characterized in that: The following steps are involved: After crossing ly8406 with PH6WC and self-pollination, the self-fertile line Z39-1 was obtained; After crossing PH4CV with LY1359, the DH line DHZ62-3 was generated by haploid induction and doubling; After hybridization of the self-fertile line Z39-1 and the DH line DHZ62-3, the drought-resistant corn variety Longdan 639 was obtained; The traits of the self-fertile line Z39-1 include: medium green leaf color of seedlings, light purple leaf sheaths, green leaf margins, and semi-compact plant type; average plant height of about 248 cm, average ear height of about 73 cm, 2 to 4 primary branches of the tassel, 19 leaves of mature plants, yellow filaments, purple anthers, conical ears, ear length of about 17.0 cm, ear diameter of about 4.8 cm, axis diameter of about 2.5 cm, 18 rows of ears, yellow and semi-hard grains, and red ear axes; The characteristics of the DH series DHZ62-3 include: a semi-compact plant type, an average plant height of 198 cm, an average ear height of 65 cm, 19 leaves on mature plants, 3 to 5 primary branches on the tassel, medium green leaves on seedlings, green leaf margins, light purple leaf sheaths, pink filaments, yellow anthers, conical ear, ear length of about 14.3 cm, 14 rows of ears, ear diameter of about 4.4 cm, axis diameter of about 2.6 cm, yellow, horse-tooth-shaped grains, and red ear axis; The self-fertile line Z39-1 was used as the female parent and the DH line DHZ62-3 was used as the male parent for hybridization.

2. The method according to claim 1, characterized in that The characteristics of the drought-resistant corn variety Longdan 639 are: green seedling leaf sheaths, green leaves, and green leaf margins; semi-compact plant type, average plant height 290 cm, ear height 102 cm, and 19 leaves on mature plants; green stem base, light purple anthers, purple husks; yellow filaments, cylindrical ears, average ear length 19.6 cm, 16 rows of ears, an average number of 35.8 grains per row, red cob, yellow, semi-dent-shaped grains, and 100-grain weight 41.9 g.

3. The method according to claim 1, characterized in that After the ly8406 was hybridized with the PH6WC and self-pollinated for 7 generations, the self-fertile line Z39-1 was obtained.

4. Use of the drought-resistant corn cultivated according to the method according to any one of claims 1 to 3 in dryland agricultural planting.

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