Method for rapid selection of soybean varieties in Guangdong and Guangxi regions

Abstract

The application discloses a rapid breeding method for soybean varieties in Guangdong and Guangxi regions, and aims at the long breeding period of conventional soybeans, the dependence on southward transplantation or artificial temperature control, the method realizes three maturing of spring soybeans in one year without the aid of southward transplantation and artificial temperature control through cultivation of F1-F7 generations in different years, combination of 30 DEG C seed germination, tray seedling transplanting, reasonable sowing period, pod picking and drying and other technologies, and the breeding period is shortened by 33.33% compared with the conventional breeding period, the operation is simple and does not need complicated equipment, the method is beneficial to popularization at the basic level, and the breeding process of new soybean varieties is effectively accelerated.

Description

Technical Field

[0001] This invention belongs to the field of agricultural planting technology and relates to a method for rapid breeding of soybean varieties in the Guangdong and Guangxi regions. Background Technology

[0002] Soybeans are an important grain, oilseed, and feed crop in my country, holding a pivotal strategic position in ensuring national food security and promoting agricultural development. Given the limited arable land resources, the fundamental solution to increasing soybean production capacity lies in improving yield per unit area through genetic modification and cultivating high-yield, high-quality new varieties.

[0003] Currently, the breeding of new soybean varieties mainly relies on conventional sexual hybridization breeding methods. Obtaining a new line with stable genetic traits through this method typically requires about seven generations of self-pollination from the F1 generation. In most parts of northern my country, where light and temperature conditions are limited, soybeans can only be grown once a year, so developing a stable line requires at least seven years. To shorten the breeding cycle, the breeding community commonly uses the "southern propagation and generation extension" technique, which involves moving soybean materials to tropical regions such as Hainan during the winter for propagation, achieving two harvests a year. Even so, developing a stable line often takes more than four years.

[0004] Compared to northern regions, low-latitude areas like Guangxi and Guangdong have abundant sunshine and heat resources, and long frost-free periods, providing natural climatic conditions for multiple soybean harvests per year. For example, theoretically, spring soybeans can be harvested twice a year without the aid of southern breeding programs; with the addition of southern breeding programs in Hainan, three harvests can be achieved annually. The average growing period for spring soybeans is about 90 days. Even with a three-crop-a-year model, approximately 90 days of sunshine and heat resources remain unutilized each year. Analysis shows that the main reason for this resource waste is that June to August in the Guangxi and Guangdong regions is typically the rainy season with concentrated rainfall. Continuous heavy rainfall leads to excessive soil moisture in the fields, making normal plowing and harrowing impossible, severely impacting land preparation and timely sowing, thus creating a nearly three-month gap in the breeding process.

[0005] In summary, existing soybean breeding technologies, whether the single-crop-a-year model in the north or the double-crop or triple-crop-a-year model utilizing southern breeding, all suffer from excessively long breeding cycles and insufficient utilization of light and heat resources. Particularly in the Guangdong and Guangxi regions, the constraints of the rainy season on field operations have become a key bottleneck limiting further improvements in breeding efficiency. Therefore, there is an urgent need in this field for a rapid breeding method that can overcome the adverse effects of the rainy season, fully utilize local light and heat resources, and significantly shorten the soybean breeding cycle. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for rapid breeding of soybean varieties in the Guangdong and Guangxi regions, which can achieve three harvests of spring soybeans per year without relying on the Hainan breeding program, effectively improving the process of breeding new soybean varieties.

[0007] This invention provides a method for rapid breeding of soybean varieties in the Guangdong and Guangxi regions, comprising the following steps:

[0008] (1) In mid-January of the first year, the F1 soybean hybrid seeds were germinated in a culture box at 28-32℃ for 1-3 days, and then sown in seedling trays containing substrate. The seedling trays were placed in a greenhouse. When the seedlings grew to the true leaf stage, they were transplanted to the field. In early May of the first year, the pods were harvested at the R6 stage (peak grain filling stage) of soybeans to obtain F2.

[0009] (2) In early May of the first year, the F2 generation pods were dried at 40℃ for 3 days, and the beans were peeled out and sown into seedling trays with holes at the bottom containing substrate. When the seedlings grew to the true leaf stage, the seedling trays were placed directly into the field. The seedling trays were arranged in rows along the length direction, and the gaps between the two rows were covered with black weeding cloth. In late July of the first year, the pods were harvested at the R6 stage of soybean (peak grain filling stage) to obtain F3.

[0010] (3) From late July to early August of the first year, the F3 generation bean pods were dried at 40℃ for 3 days, and then the beans were peeled out and sown in the field. In late October of the first year, the bean pods were harvested after the soybean plants matured to obtain F4.

[0011] (4) After drying and threshing the F4 generation pods, they were sown in the field in mid-January of the second year. In early May of the second year, the pods were harvested at the R6 stage (peak grain filling stage) of soybeans to obtain F5.

[0012] (5) In early May of the second year, the F5 generation pods were dried at 40℃ for 3 days, and the beans were peeled out and sown into seedling trays with holes at the bottom containing substrate. When the seedlings grew to the true leaf stage, the seedling trays were placed directly into the field. The seedling trays were arranged in rows along the length direction, and the gaps between the two rows were covered with black weeding cloth. From late July to early August of the second year, the pods were harvested at the R6 stage (peak grain filling stage) of soybeans to obtain F6.

[0013] (6) In early August of the second year, the F6 generation pods were dried at 40°C for 3 days, and the beans were peeled out and sown in the field. The F7 generation seeds were harvested in early November of the second year when the plants matured.

[0014] The substrate is peat moss. Produced by Changchun Saisheng Peat Technology Co., Ltd.

[0015] In step (1), the germination temperature is 30℃ and the germination time is 2 days.

[0016] In steps (2) and (5), when sowing beans in the seedling tray, one bean is sown in each hole. The sowing method in the seedling tray is as follows: after sowing a row of beans along the length of the seedling tray, leave an empty row (i.e., a row without sowing) and then continue sowing the next row, and so on. The spacing between each row of seedling trays is 60cm.

[0017] In steps (3), (4), and (6), the soybeans are sown in rows in the field with a row spacing of 40cm and a row length of 400cm.

[0018] The beneficial effects of this invention are:

[0019] This invention combines techniques such as pod drying, tray transplanting and direct planting, and reasonable sowing time to achieve three harvests of spring soybeans per year in large-scale material breeding without the need for artificial temperature control or southern breeding. This shortens the cycle by 33.33% compared to conventional soybean new line breeding (without southern breeding), effectively improving the process of new soybean variety breeding. Moreover, the simple operation method can be implemented without complicated equipment, which is conducive to grassroots promotion. Attached Figure Description

[0020] Figure 1 Diagram of sowing in seedling trays

[0021] exist Figure 1 Soybean seeds are planted in the white circle in the middle.

[0022] Figure 2 Arrangement of seedling trays in the field

[0023] exist Figure 2 In the middle, the black strips between the rows of seedling trays are weed-proof cloth.

[0024] Figure 3 Experimental results on timely pod harvesting to shorten the soybean breeding cycle Detailed Implementation

[0025] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the present invention.

[0026] Example 1: Rapid Breeding Method for Soybean Varieties in Guangdong and Guangxi Regions

[0027] In July 2021, soybean varieties Guichun 1902 and Guichundou 104 were sown. Using Guichun 1902 as the female parent and Guichundou 104 as the male parent, hybrid seeds F1 were obtained through sexual hybridization.

[0028] On January 15, 2022, the F1 hybrid seeds were germinated for 2 days in an incubator at 30℃, then sown in seedling trays with holes at the bottom containing peat moss. These trays were then placed in a simple greenhouse at the Mingyang Base of the Guangxi Academy of Agricultural Sciences in Nanning. Once the seedlings reached the true leaf stage, they were transplanted to the field. The hybrid offspring entered the R6 stage (peak grain-filling stage) on May 2, 2022, after which the pods were harvested to obtain the F2 generation.

[0029] After air-drying F2 seeds in an electric heating drying oven at 40℃ for 3 days, the seeds were peeled and sown on May 6, 2022, into 50-cell seedling trays (54cm*28cm) with holes at the bottom, containing peat moss. One seed was sown in each cell along the length of the tray, and a row was sown every other cell along the width of the tray. Figure 1 When the soybeans reach the true leaf stage, place them directly in the field at the Nanning Mingyang Base of the Guangxi Zhuang Autonomous Region Academy of Agricultural Sciences, along with their seedling trays. The seedling trays should be arranged in a row, with the first and last trays connected end-to-end along the length of the field. The distance between the seedling trays in each row should be 60cm. Cover the gaps between the seedling trays with black weed-control tarpaulin. Figure 2 Before placing the seedling trays in the field, a low-toxicity pre-emergence herbicide is sprayed for weed control. The seedling trays have holes at the bottom; after the soybeans germinate, their roots will grow into the soil through these holes. On July 27, 2022, after most soybeans had entered R6, one pod was harvested from each plant to obtain F3.

[0030] After air-drying F3 seeds in a 40℃ electric drying oven for 3 days, the seeds were hulled and sown on August 1, 2022, in the field at the Mingyang Base of the Guangxi Academy of Agricultural Sciences in Nanning City. Sowing was done in rows with a row spacing of 40cm and a row length of 400cm. A low-toxicity pre-emergence herbicide was applied to seal the soil on the same day. On October 27, 2022, after the plants matured, one pod of F4 was harvested from each plant.

[0031] After drying and threshing, F4 seeds were row-sown on January 15, 2023, at the Mingyang Base of the Guangxi Academy of Agricultural Sciences in Nanning City, with a row spacing of 40cm and a row length of 400cm. On May 5, 2023, when most plants entered the R6 stage, the superior plants were selected, pods were picked, and placed in mesh bags in an electric heating drying oven at 40℃ for 3 days before being shelled to obtain F5 seeds.

[0032] F5 seeds were sown on May 10, 2023, in seedling trays containing peat moss, using the same planting method as in 2022. By July 30, 2023, most plants had entered the R6 stage. The best plants were selected, their pods were removed, and they were placed in mesh bags and air-dried in a 40℃ electric hot air drying oven for 3 days before being shelled to obtain F6 seeds.

[0033] F6 seeds were sown on August 5, 2023, at the Mingyang Base of the Guangxi Academy of Agricultural Sciences in Nanning City, using row sowing with a row spacing of 40cm and a row length of 400cm. On November 2, 2023, when the plants matured, the best plants were selected, threshed, and dried to obtain F7 seeds.

[0034] On February 25, 2024, the above-mentioned F7 seeds were planted, with soybean Guichun 8 as a control. On July 13, 2024, when the plants matured, row 24CJ108, which had better growth than Guichun 8, was selected from the above-mentioned F7 generation plants for harvest. The yield of the two was counted. The results showed that the yield of 24CJ108 was 4.7% higher than that of Guichun 8, and it was named Guichun Black 7.

[0035] Under conventional breeding methods, spring soybeans in Nanning are harvested twice a year. Starting from the summer of 2021 when hybrid pods are obtained, stable F7 seeds need to be obtained after the summer of 2024 when they are sown and harvested. The finished product will be available in the summer of 2025. The rapid breeding method of this invention is one year faster than the traditional method, increasing the breeding speed by 33.33%.

[0036] Example 2: High-temperature germination to accelerate soybean emergence experiment

[0037] Using soybean varieties GC15 (Guichun 15) and GC206 (Guichun 206) as materials, a sowing experiment under different conditions was conducted on January 15, 2023, at the Mingyang Base of the Guangxi Academy of Agricultural Sciences in Nanning. T1: Direct sowing in the field; T2: Germination in a 30℃ incubator for 2 days followed by sowing in the field; T3: Sowing in flowerpots and placing them in a simple greenhouse; T4: Germination in a 30℃ incubator for 2 days, then planting in flowerpots and placing them in a simple greenhouse.

[0038] Germination method: Soybean seeds were placed on three sheets of moistened tissue paper, wrapped, and then covered with another layer of moistened germination paper. The ends were then tied with rubber bands and placed in a 30℃ incubator for 2 days to germinate. Experimental results showed that seedlings emerged after 14 days (T1), 9 days (T2, including germination time), 8 days (T3), and 5 days (T4, including germination time) under field conditions. Germination under field conditions resulted in seedling emergence 5 days earlier than normal sowing, accelerating the process by 35.71%. Germination under greenhouse conditions resulted in seedling emergence 3 days earlier than normal sowing, accelerating the process by 37.50%.

[0039] Example 3: Experiment on shortening the soybean breeding cycle by timely pod harvesting

[0040] Using soybean varieties Guichun 15 (GC15) and GC206 (Guichun 206) as materials, soybeans were planted at the Mingyang Base of the Guangxi Academy of Agricultural Sciences on January 18, 2023. Each plot was 4m long and 1.2m wide, with 3 rows of soybeans planted in each plot, with a row spacing of 40cm and a plant spacing of 20cm. Three replicates were set. Both varieties emerged on January 29. The R1 (initiation of flowering) for GC206 and GC15 were March 25 and March 31, respectively; the R6 (peak grain filling) for GC206 and GC15 were May 7 and May 6, respectively; the R7 (initial maturity) for GC206 and GC15 were May 28 and May 25, respectively; and the R8 (full maturity) for GC206 and GC15 were June 2 and May 31, respectively. Soybean pods with uniformly fullness were placed in a 40℃ electric drying oven. Samples were taken on days 1, 2, 3, 4, 5, and 6 after drying. The dried samples, along with the control (CK), were stored in a 4℃ refrigerator for later use. After sample processing, the pods, along with the CK, were dehulled. Soybean seed germination was tested using the paper bed method as described in GB / T3543.4—1995 "Specifications for Crop Seed Inspection - Germination Test". Thirty intact seeds were placed in a germination box (length × width × height: 12 cm × 12 cm × 6 cm) lined with two layers of moist germination paper. Two more layers of moist germination paper were then placed on top, and the box was placed in a 25℃ germination chamber for germination. The number of germinated seeds and the number of normal seedlings were counted on days 3 and 5. Germination seed count: the number of seeds with a radicle length ≥ 1 cm; Normal seedling count: the number of seedlings with no obvious damage to the cotyledons, true leaf buds, hypocotyl, and roots. Then, referring to the method of Chen Wenjie et al. (2025), the germination potential and normal seedling rate of each treatment were calculated. Germination potential = (number of germinated seeds on day 3 / number of tested seeds) × 100%; Normal seedling rate = (number of normal seedlings / number of tested seeds) × 100%.

[0041] The experimental results show that at 40℃, with the extension of drying time, both the pod color and the grain color gradually change from green to yellow. Figure 3 As the soybeans gradually dehydrate and dry, the moisture content of the soybean seeds drops below 13% after 6 days of drying. The color change is most noticeable on the 3rd day, when the seeds change from green to yellow, and they begin to dehydrate, feeling noticeably soft when squeezed. Germination results show that GC206 and GC15 varieties had the lowest germination vigor and normal seedling rate with fresh pods, followed by those dried for 1 day. Drying for 2 days significantly improved germination vigor and normal seedling rate compared to fresh pods, with GC206 showing increases of 78.77% and 80.00% respectively, and GC15 showing increases of 64.45% and 67.78% respectively. Drying for 3 days resulted in the highest germination vigor and normal seedling rate (Table 3). Sowing GC206 and GC15 varieties 3 days after pod harvesting and drying at the R6 stage can advance sowing by at least 23 days and 22 days respectively.

[0042] Table 3. Effects of different drying times after pod harvesting on germination ability of GC206 and GC15 varieties.

[0043] .

Claims

1. A method for rapid breeding of soybean varieties in the Guangdong and Guangxi regions, characterized in that, Includes the following steps: (1) In mid-January of the first year, the F1 soybean hybrid seeds were germinated in a culture box at 28-32℃ for 1-3 days, and then sown in seedling trays containing substrate. The seedling trays were placed in a greenhouse. When the seedlings grew to the true leaf stage, they were transplanted to the field. In early May of the first year, the pods were harvested at the R6 stage (peak grain filling stage) of soybeans to obtain F2. (2) In early May of the first year, the F2 generation pods were dried at 40℃ for 3 days, and the beans were peeled out and sown into seedling trays with holes at the bottom containing substrate. When the seedlings grew to the true leaf stage, the seedling trays were placed directly into the field. The seedling trays were arranged in rows along the length direction, and the gaps between the two rows were covered with black weeding cloth. In late July of the first year, the pods were harvested at the R6 stage of soybean (peak grain filling stage) to obtain F3. (3) From late July to early August of the first year, the F3 generation bean pods were dried at 40℃ for 3 days, and then the beans were peeled out and sown in the field. In late October of the first year, the bean pods were harvested after the soybean plants matured to obtain F4. (4) After drying and threshing the F4 generation pods, they were sown in the field in mid-January of the second year. In early May of the second year, the pods were harvested at the R6 stage (peak grain filling stage) of soybeans to obtain F5. (5) In early May of the second year, the F5 generation pods were dried at 40℃ for 3 days, and the beans were peeled out and sown into seedling trays with holes at the bottom containing substrate. When the seedlings grew to the true leaf stage, the seedling trays were placed directly into the field. The seedling trays were arranged in rows along the length direction, and the gaps between the two rows were covered with black weeding cloth. From late July to early August of the second year, the pods were harvested at the R6 stage (peak grain filling stage) of soybeans to obtain F6. (6) In early August of the second year, the F6 generation pods were dried at 40°C for 3 days, and the beans were peeled out and sown in the field. The F7 generation seeds were harvested in early November of the second year when the plants matured.

2. The method according to claim 1, characterized in that, The substrate is peat soil.

3. The method according to claim 1, characterized in that, The germination temperature in step (1) is 30℃, and the germination time is 2 days.

4. The method according to claim 1, characterized in that, In steps (2) and (5), when sowing beans in the seedling tray, one bean is sown in each hole. The sowing method in the seedling tray is as follows: after sowing a row of beans along the length of the seedling tray, leave an empty row (i.e., a row without sowing) and then continue sowing the next row, and so on. The spacing between each row of seedling trays is 60cm.

5. The method according to claim 1, characterized in that, In steps (3), (4), and (6), the soybeans are sown in rows in the field with a row spacing of 40cm and a row length of 400cm.

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