A method for creating maize germplasm specifically for grain and forage or for silage

Abstract

This invention discloses a method for creating maize germplasm specifically for grain and forage or silage, relating to the field of bio-breeding technology. The method includes the following steps: Zheng 58 and PH6WC are crossed, and then self-crossed to obtain the inbred line GNK29-3; the Suwan germplasm is crossed with Iodent germplasm, and then haploidized and doubled to produce the DH line GNK2073-1; the inbred line GNK29-3 and the DH line GNK2073-1 are then crossed to obtain maize germplasm and varieties specifically for grain and forage or silage. This germplasm creation method can provide high-quality germplasm resources for silage maize breeding, effectively increase dry matter yield, and provide an efficient technical path for silage maize germplasm creation, possessing extremely high agricultural promotion and industrial application value.

Description

Technical Field

[0001] This invention relates to the field of biological breeding technology, and in particular to a method for creating maize germplasm specifically for grain and forage or for silage. Background Technology

[0002] Silage corn is a core high-quality feed source for livestock development, possessing dual value as both grain and forage. Innovation and improvement of its germplasm resources are crucial for promoting the upgrading of the feed industry and ensuring the supply of feed grains. With the accelerated development of large-scale and intensive livestock farming, the demand for silage corn continues to grow, placing higher demands on its varietal characteristics. It needs to possess high biomass yield and dry matter content to ensure feed supply, excellent nutritional quality, and agronomic traits suitable for the planting environment, such as good stress resistance, lodging resistance, and greenness retention. Therefore, dual-purpose (grain and forage) or silage-specific corn germplasm has become a research focus in the breeding field.

[0003] While significant progress has been made in silage maize breeding, numerous challenges remain. Existing silage maize germplasm suffers from a relatively narrow genetic base, and insufficient innovation and integration of breeding materials. This results in most varieties failing to meet the dual demands of grain yield and biomass production. Furthermore, some silage-specific varieties exhibit poor green retention and weak stress resistance, failing to meet the high-standard feeding requirements of large-scale livestock farming. Traditional maize breeding research has largely focused on grain production, with silage maize breeding starting relatively late. A targeted germplasm creation system is lacking, and the integration and application of breeding methods and technologies are not yet mature.

[0004] While various maize germplasm resources each carry different desirable traits—some exhibit outstanding resistance to diseases and pests, others possess superior ear traits and high grain yields, and still others boast compact plant type and strong adaptability—a single germplasm resource is insufficient to meet the comprehensive breeding goals of silage maize, and the advantageous traits of different superior germplasms are difficult to efficiently integrate. Furthermore, traditional conventional breeding methods suffer from long breeding cycles and low screening efficiency. Even though some modern breeding technologies, especially haploid breeding technology, have been applied to maize breeding, their integration with conventional breeding methods still lacks systematic design, making it difficult to quickly and accurately create high-quality breeding materials that meet the needs of silage maize breeding.

[0005] Furthermore, the planting environment for silage maize is diverse, with significant differences in climate and soil conditions across different regions. This leads to varying requirements for traits such as growth period, plant type, and stress resistance among varieties. Existing silage maize varieties have limited adaptability, and in some planting areas, they are prone to problems such as insufficient yield stability and poor agronomical traits, hindering widespread planting. Therefore, there is an urgent need to explore an efficient and suitable germplasm creation and seed production technology system for silage maize. Summary of the Invention

[0006] The purpose of this invention is to provide a method for creating maize germplasm specifically for grain and forage or silage production, thereby addressing the problems existing in the prior art. This method provides technical support for creating maize germplasm resources specifically for grain and forage or silage production, and has significant value for agricultural promotion and application.

[0007] To achieve the above objectives, the present invention provides the following solution: This invention provides a method for creating maize germplasm specifically for grain and forage or for silage, comprising the following steps: After crossing Zheng 58 with PH6WC, the inbred line GNK29-3 was obtained through self-pollination. After crossing Suwan germplasm with Iodent germplasm, haploid induction and chromosome doubling were performed to produce the DH line GNK2073-1; The inbred line GNK29-3 and the DH line GNK2073-1 were hybridized to obtain the maize germplasm specifically for grain and forage or silage.

[0008] Furthermore, hybridization was carried out using the inbred line GNK29-3 as the female parent and the DH line GNK2073-1 as the male parent.

[0009] Furthermore, the traits of the inbred line GNK29-3 include: yellow seeds, semi-dental, 100-seed weight 30.5 g; green seedlings, light purple leaf sheaths, and green leaf margins; plant height 285 cm, ear position 102 cm, semi-compact plant type, 19 leaves per mature plant, purple anthers, and yellow filaments; conical ear, red cob, ear length 16.0 cm, 14 rows of ears, 31.0 kernels per row, ear diameter 3.6 cm, and cob diameter 2.6 cm.

[0010] Furthermore, the characteristics of the DH line GNK2073-1 include: yellow kernels, semi-hard kernel shape, 100-kernel weight of 29.7 g; green seedlings, light purple leaf sheaths, and green leaf margins; plant height of 227 cm, ear position of 73 cm, semi-compact plant type, 20 leaves per mature plant, yellow anthers, and yellow filaments; conical ear, white cob, ear length of 18.0 cm, 20 rows of kernels per ear, 31.0 kernels per row, ear diameter of 4.6 cm, and cob diameter of 3.0 cm.

[0011] Furthermore, the characteristics of the corn germplasm specifically for grain and forage or silage are as follows: yellow kernels, semi-dent shape, 100-kernel weight 37.5 g; purple leaf sheaths, green leaves, and green leaf margins in seedlings; semi-compact plant type, plant height 305 cm, ear height 128 cm, 20 leaves per mature plant; purple stem base, light purple anthers, green glumes, and yellow silks; cylindrical ear, 20.9 cm long, 16-18 rows of kernels per ear, 40.9 kernels per row, and red cob.

[0012] Furthermore, after crossing Zheng 58 with PH6WC, and undergoing 7 generations of self-pollination, the inbred line GNK29-3 was obtained. This invention utilizes the domestic Reid germplasm inbred line Zheng 58, which has large ears and kernels, but poor kernel quality after maturity. Its endosperm is composed of starchy starch, with only a small amount of corneous starch in the outer layer, resulting in a soft texture, high cob water content, and slow water loss (i.e., slow dehydration). The invention introduces the American backbone inbred line PH6WC, belonging to the SS (sturdy stalk) group. Its kernels have corneous endosperm at the top and around the edges, resulting in good quality, early maturity, and strong adaptability. Utilizing the excellent kernel quality, rapid dehydration, and generally good combining ability of this inbred line, a new germplasm with high biological yield and excellent kernel quality is bred. This creates a new high-yield, high-quality dual-purpose corn or silage corn germplasm, solving the problem of poor quality in domestic Reid germplasms such as Zheng 58.

[0013] Furthermore, after hybridization of the Suwan germplasm and Iodent germplasm, haploid induction and chromosome doubling were performed to produce the DH line GNK2073-1. This invention introduces Suwan germplasm, a tropical material, which improves the disease resistance and lodging resistance of silage maize germplasm. Simultaneously, by utilizing Iodent germplasm, it maintains temperate lineage, ensuring high yield, stable yield, and a suitable maturity period for northern planting. This "warm-tropical" integration creates a new dual-purpose (grain and forage) maize or silage maize germplasm with improved disease and lodging resistance, while avoiding the problem of prolonged growth periods and premature maturity associated with tropical materials grown in the north.

[0014] The present invention also provides the application of maize germplasm for dual use as grain and feed or for silage, cultivated according to the above method, in the planting of silage maize.

[0015] The present invention discloses the following technical effects: This invention successfully created maize germplasm specifically for grain and forage or silage, achieving precise aggregation of superior traits from different high-quality germplasms. The bred germplasm exhibits excellent agronomical traits, significantly increased 100-kernel weight, cylindrical ear shape with long ears and outstanding row kernel count, and significant advantages in biomass and dry matter yield. This germplasm's growth period is suitable for silage harvesting, exhibits excellent lodging resistance, significantly improved greenness retention, moderate resistance to Fusarium wilt, and good overall stress resistance. It is suitable for mulching planting and maintains stable yield and trait performance in multiple regions. The germplasm creation method of this invention can provide high-quality germplasm resources for silage maize breeding, offering an efficient technical path for silage maize germplasm creation, and possesses extremely high agricultural promotion and industrial application value. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart of the breeding process for Longqing No. 5; Figure 2 This is a comparison chart of the ears of Longqing No. 5 and the control variety Jindan No. 73. Detailed Implementation

[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0019] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0020] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0021] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0022] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0023] Unless otherwise specified, the maize base materials used in the following examples were all provided by the Germplasm Resource Bank of Gansu Academy of Agricultural Sciences.

[0024] Comparison variety 1: Yuyu 22 is a maize variety approved by the state in 2000, with the approval number: Guoshenyu 20000012.

[0025] Control variety 2: Jindan 73 (also known as Jindan No. 73) is a mid-to-late maturing maize hybrid bred by Beijing Denong Seed Industry Co., Ltd. (or in conjunction with Jinyang Maize Research Institute of Yanggao County, Shanxi Province). It has been approved in multiple provinces including Shanxi, Hebei, Ningxia, Gansu, and Jilin, with approval numbers including Jin Shen Yu 2010009 (Shanxi), Ning Shen Yu 20160009 (Ningxia), Ji Shen Yu 20170072 (Hebei), and Gan Shen Yu 2015008 (Gansu).

[0026] Zheng 58 has been published in the literature “Zhang Falin. Breeding and application of excellent maize inbred line Zheng 58 [J]. Crop Journal, 2001, 000(004): 31-31. DOI: 10.3969 / j.issn.1001-7283.2001.04.026.”

[0027] PH6WC has been published in the literature “Feng Guang, Zhao Hongxu, Wang Xiaojie, et al. Study on combining ability of maize inbred line Zheng 58 × PH6WC double-loop selection line [J]. Maize Science, 2021, 29(05):22-27.DOI:10.13597 / j.cnki.maize.science.20210503”.

[0028] The Suwan germplasm Suwan 1 was provided by the Guizhou Academy of Agricultural Sciences as the female parent; the Iodent germplasm 702 was provided by the germplasm resource bank of the Gansu Academy of Agricultural Sciences as the male parent.

[0029] Example 1 This invention uses GNK29-3 as the female parent and GNK2073-1 as the male parent for hybridization to cultivate a new maize germplasm specifically for grain and forage or silage, named Longqing No. 5. The specific breeding process (e.g.) Figure 1 As shown below: Using the base material of the female parent Zheng 58 (Reid type) and the male parent PH6WC (SS type), the inbred line was obtained through seven generations of self-pollination and selection in Zhangye and Hainan, and named GNK29-3. The specific process is shown in Table 1.

[0030] Table 1. Breeding process of Longqing No. 5 Traits of the inbred line GNK29-3: ① Seed characteristics: The seeds are yellow, semi-dentate, and the weight of 100 seeds is 30.5 grams.

[0031] ②Plant characteristics: Seedlings are green, leaf sheaths are light purple, and leaf margins are green. Plant height is 285 cm, ear height is 102 cm, plant type is semi-compact, mature plants have 19 leaves, anthers are purple, and filaments are yellow.

[0032] ③ Harvest characteristics: The ears are conical with a red cob, 16.0 cm long, 14 rows of kernels, 31.0 kernels per row, 3.6 cm in diameter, and 2.6 cm in cob diameter.

[0033] ④ Resistance: Resistant to lodging, corn leaf blight and stalk rot.

[0034] ⑤ Growth period: 136 days from emergence to maturity.

[0035] Using the maternal parent Suwan germplasm Suwan 1 (heat source material) and the paternal parent Iodent germplasm 702 as the basic material, haploid induction and chromosome doubling were performed on the F2 generation to produce an excellent DH (Double Haploid) line, named GNK2073-1 (the double haploid obtained by haploid doubling is the DH line, also known as the DH population). The specific process is shown in Table 1.

[0036] The characteristics of DH series GNK2073-1 are as follows: ① Seed characteristics: The seeds are yellow, semi-hard, and weigh 29.7 grams per 100 seeds.

[0037] ②Plant characteristics: Seedlings are green, leaf sheaths are light purple, and leaf margins are green. Plant height is 227 cm, ear height is 73 cm, plant type is semi-compact, mature plants have 20 leaves, anthers are yellow, and filaments are yellow.

[0038] ③ Harvest characteristics: The ear is conical with a white cob, 18.0 cm long, 20 rows of kernels, 31.0 kernels per row, 4.6 cm in diameter, and 3.0 cm in cob diameter.

[0039] ④ Resistance: Resistant to corn leaf blight and stalk rot.

[0040] ⑤ Growth period: 135 days from emergence to maturity.

[0041] Using GNK29-3 as the female parent and GNK2073-1 as the male parent, after hybridization, the F1 offspring with the following traits were selected, which are maize germplasm for dual-purpose grain and forage or silage, and named Longqing No. 5: ① Seed characteristics: The seeds are yellow, semi-dental, and weigh 37.5 grams per 100 seeds.

[0042] ② Plant characteristics: Seedlings have purple leaf sheaths, green leaves, and green leaf margins. The plant type is semi-compact, with a plant height of 305 cm and an ear height of 128 cm. Mature plants have 20 leaves. The stem base is purple, the anthers are light purple, the glumes are green, and the filaments are yellow.

[0043] ③ Harvest characteristics: The ear is cylindrical, 20.9 cm long, with 16-18 rows of kernels, 40.9 kernels per row, and a red cob (see...). Figure 2 ).

[0044] ④ Resistance: Inoculation tests show that this variety is moderately resistant to Pythium stalk rot, moderately resistant to head smut, susceptible to large leaf spot, and resistant to lodging.

[0045] ⑤ Growth period: 138 days from emergence to harvest.

[0046] This invention employs small-scale field hybridization for seed production. The primary task in the pre-pollination stage is covering the female ears. Before the female ears of the female parent emerge their silks, they are covered with new sulfuric acid paper bags to prevent the silks from coming into contact with pollen from other male parent species for fertilization. Therefore, the female ears of the female parent must be strictly bagged. As the female ears develop and grow, they gradually emerge their silks within the sulfuric acid paper bag, ensuring the silks remain uncontaminated. The first ear should be correctly selected; the female ear should not be too small, and ears that have already emerged silks should not be bagged. When bagging, one side of the bag should be tightly against the leaf sheath, and the other side should be tightly against the stem. If an inbred line has silks emerging before or only partially from the leaf sheath, the leaf sheath can be peeled open before bagging. When the glumes of the male ear open and the anthers are exposed, the bagging of the male ear can begin. The afternoon before hybridization pollination, all the male spikes to be pollinated are covered with large sulfuric acid paper bags. When covering the male spikes, first open the paper bag, then hold the paper bag with one hand and the internode of the male spike with the other hand, completely covering the male spike with the paper bag. Then fold the opening of the paper bag around the stem and use a pin to pierce the stem to secure the paper bag. This is to prevent other pollen from falling and impure pollen from causing insufficient purity of the seeds after hybridization. The following morning, between 9 and 11 a.m., pollen was collected during the peak pollination period. All the pollen in the sulfuric acid paper bags was collected together, sieved to remove the anthers, and a large amount of pollen was collected. The male parent's pollen was then evenly sprinkled onto the filaments of the female parent's bag. (During pollination, the sulfuric acid paper bags were gently removed first. Generally, during hybridization, if the filaments of the female ear in the bag protrude too far, the longer filaments were uniformly cut off with scissors or other tools, leaving 1-2 cm of "brush-like filaments." The pollen was then quickly and evenly shaken onto the filaments of the female ear.) After the pollen came into contact with the filaments, a sulfuric acid paper bag of a different color was quickly placed over the pollinated female ear to gradually complete fertilization and development. The seeds were then harvested after they matured.

[0047] In seed production in the Hexi Corridor of Gansu Province, a 50-meter field isolation strip is generally used for isolation. Male and female parents are sown together, with a parent-to-parent ratio of 1:5 being ideal. The female parent should maintain 5000 plants / mu, and the male parent 1000-1500 plants / mu. During thinning and seedling establishment, weeding and removing inferior plants are carried out. Before tasseling, both parents undergo 2-3 rounds of weeding and tasseling, with timely detasseling. Tasseling begins when the female parent's tassel has not yet emerged, while the female parent's tassel is removed by removing 1-2 leaves from the tassel before tasseling. The male parent's flowering period coincides with the female parent's silking period, allowing pollen from the male parent to fall onto the silks of the female parent's ear, completing fertilization. Large-scale seed production uses an open "natural pollination" method for hybridization. After pollination, the male parent is removed. During critical growth periods, timely fertilization and watering are essential.

[0048] Example 2 1. Experimental Design A planting trial was conducted using Longqing No. 5, selected in Example 1, with Yuyu No. 22 as a control. The experimental method is as follows: The experiment was conducted under mulched conditions, using a randomized block design with three replicates, 5 rows per plot, row length of 7 meters, row spacing of 0.5 meters, and a planting density of 5000 plants / mu. When the milk line of each variety reached half of its grain-filling stage, 2 plants were removed from one end of the plot, and 20 plants were selected and harvested from 20 cm above the ground. The fresh grass weight was measured, then blanched at 105℃ and dried at 70℃ to constant weight. The dry matter yield was then calculated.

[0049] 2. Test Results (1) Production performance As shown in Table 2, the average dry matter yield of Longqing No. 5 at five different locations in Gansu Province was 6.4% higher than that of Yuyu No. 22.

[0050] Table 2. Dry matter yield of the tested varieties Note: All data are average production values ​​for 2022 and 2023.

[0051] (2) Reproductive period and resistance The growth period, stress resistance, varietal yield and stability of Longqing 5 and the control are shown in Tables 3-5.

[0052] Table 3 Summary of silage harvesting time and field stress resistance of the tested varieties Note: Field natural disease resistance index: Level 1 is highly resistant, Level 3 is resistant, Level 5 is moderately resistant, Level 7 is susceptible, and Level 9 is highly susceptible.

[0053] Table 4. Results of Disease Inoculation Identification for Tested Varieties Note: MR represents neutral resistance; S represents disease infection.

[0054] Table 5. Analysis of the high yield and stability of varieties The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for creating maize germplasm specifically for grain and forage or for silage, characterized in that, Includes the following steps: After crossing Zheng 58 with PH6WC, the inbred line GNK29-3 was obtained through self-pollination. After crossing Suwan germplasm with Iodent germplasm, haploid induction and chromosome doubling were performed to produce the DH line GNK2073-1; The inbred line GNK29-3 and the DH line GNK2073-1 were hybridized to obtain the maize germplasm specifically for grain and forage or silage.

2. The method according to claim 1, characterized in that, The inbred line GNK29-3 was used as the female parent and the DH line GNK2073-1 was used as the male parent for hybridization.

3. The method according to claim 1, characterized in that, The traits of the inbred line GNK29-3 include: yellow, semi-dent seeds with a 100-seed weight of 30.5 g; green seedlings with light purple leaf sheaths and green leaf margins; plant height of 285 cm, ear height of 102 cm, semi-compact plant type, 19 leaves per mature plant, purple anthers, and yellow filaments; conical ear with a red cob, 16.0 cm long, 14 rows of kernels per ear, 31.0 kernels per row, ear diameter of 3.6 cm, and cob diameter of 2.6 cm.

4. The method according to claim 1, characterized in that, The characteristics of the DH line GNK2073-1 include: yellow kernels, semi-hard kernel shape, 100-kernel weight of 29.7 g; green seedlings, light purple leaf sheaths, and green leaf margins; plant height of 227 cm, ear position of 73 cm, semi-compact plant type, 20 leaves per mature plant, yellow anthers, and yellow filaments; conical ear, white cob, ear length of 18.0 cm, 20 rows of kernels per ear, 31.0 kernels per row, ear diameter of 4.6 cm, and cob diameter of 3.0 cm.

5. The method according to claim 1, characterized in that, The characteristics of the corn germplasm specifically for grain and forage or silage are as follows: yellow kernels, semi-dent shape, 100-kernel weight 37.5 g; purple leaf sheaths, green leaves, and green leaf margins in seedlings. Semi-compact plant type, plant height 305 cm, ear height 128 cm, 20 leaves per mature plant; purple stem base, light purple anthers, green glumes, and yellow silks; cylindrical ear, 20.9 cm long, 16-18 rows of kernels per ear, 40.9 kernels per row, and red cob.

6. The method according to claim 1, characterized in that, After Zheng 58 was crossed with PH6WC, and after 7 generations of self-pollination, the inbred line GNK29-3 was obtained.

7. The application of a dual-purpose (grain and forage) or silage-specific maize germplasm cultivated according to any one of claims 1-6 in the cultivation of silage maize.

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