Method for comprehensively improving maturing rate of sugarcane hybrid seeds

Abstract

The invention discloses a method for comprehensively improving the maturing rate of sugarcane hybrid seeds, and relates to the technical field of sugarcane cultivation. According to the method, the male parent is optimally cultured by adopting the microbial agent and the male parent nutrient solution, so that the flowering period of the male parent is prolonged, and the pollen amount and pollen viability are increased; according to the method, a female parent nutrient solution is adopted for carrying out optimized culture on a female parent, the female parent is subjected to humidification and low-temperature treatment before pollination to reduce pollen activity, female flower development is synchronously stimulated, the flowering period of the female parent is prolonged, the pollinability of female flowers is improved, the selfing rate of sugarcane is greatly reduced, and the hybridization efficiency is improved; by adopting the method disclosed by the invention, the maturing rate of the sugarcane hybrid seeds can be increased by 20-30%.

Description

Technical Field

[0001] This invention relates to the field of sugarcane cultivation technology, and in particular to a method for comprehensively improving the seed setting rate of hybrid sugarcane seeds. Background Technology

[0002] Hybridization is a major method for sugarcane germplasm innovation and new variety breeding. Obtaining sufficient hybrid seeds is crucial to the success of new sugarcane variety breeding. The current method for sugarcane hybrid seed production involves first cultivating regenerated plants by budding and rooting the parent plants. When the sugarcane has already produced tassels and the florets have begun to open, the regenerated plants are cut from the budding and rooted parts and placed in a hybridization chamber for hydroponics. Then, the female and male parents are artificially pollinated and hybridized. Currently, sugarcane hybrid seed production has the following drawbacks: 1. Sugarcane flowers are large, terminal panicles with 6,000 to 18,000 spikelets per spikelet. Each spikelet contains one ovary, two stigmas, and three to four anthers, making it a hermaphroditic plant. Because sugarcane spikelets are extremely small, it is difficult to artificially remove the male flowers. Even if removal is possible, the methods used will have an adverse effect on the female flowers (currently, the hot water or chemical methods used for removal will have an adverse effect on the female flowers). Therefore, hybrid offspring are prone to producing a large number of self-pollinated offspring, sometimes as high as 40% or more. The seed setting rate of hybrid seeds is low, which seriously affects the efficiency of sugarcane breeding. 2. Regenerated plantlets are easily affected by environmental and nutritional factors during cultivation, resulting in poor root vitality and insufficient nutrient supply. This leads to a short flowering period for the female parent (generally around 5 days), poor pollination ability of the stigma, lower pollination efficiency, and consequently, a lower seed set rate. Similarly, the male parent will have a short flowering period, low pollen quantity, and low pollen viability, requiring a larger number of male parents to meet the pollen demand, increasing the consumption of male parent material, and further reducing pollination efficiency and seed set rate. Therefore, preventing low seed set rates in hybrids due to self-pollination, improving the pollination ability of the female parent, and enhancing the pollen viability of the male parent to ultimately improve the seed set rate of hybrid seeds are urgent problems to be solved in the field of sugarcane hybrid seed production. Summary of the Invention

[0003] To address the above shortcomings, this invention provides a method for comprehensively improving the seed setting rate of sugarcane hybrid seeds, solving the problems of high self-pollination rate and low seed setting rate in current sugarcane hybrid seed production. The specific technical solution is as follows:

[0004] A method for comprehensively improving the seed setting rate of sugarcane hybrid seeds includes the following steps:

[0005] (1) Parent planting: According to the hybridization plan, sugarcane parents are planted in spring. In the early stage of ear incubation, rooting is carried out by wrapping the stem. The wrapping rooting involves selecting 1-2 nodes in the upper part of the sugarcane stem and wrapping them with a root-promoting substrate. The root-promoting substrate is mud or coconut coir with added root-promoting agent and wrapped with plastic film to promote root growth. Microbial agents are added to the root-promoting substrate of the male parent.

[0006] The microbial inoculant includes 15-27 parts of soybean rhizobium, 20-33 parts of Bacillus subtilis, 10-19 parts of shortwave monocytogenes, 5-12 parts of acetic acid bacteria, and 8-15 parts of lipogenic nitrogen-fixing spirochetes.

[0007] (2) Pre-pollination management: When the parent plants have already produced spikes and the florets have begun to open, cut the sugarcane parent plants from the lower part of the stalk 2-5cm for cultivation. The female plants are placed in the female nutrient solution for cultivation, and the male plants are placed in the male nutrient solution for cultivation. The female plants and male plants are placed in different cultivation rooms for cultivation.

[0008] Mother plant management: Every night, the mother plant is cooled down and then restored to the normal culture temperature. The cooling treatment is to treat the mother plant at 8-12℃ for 6-8 hours. On the day before pollination, the humidity is controlled at above 95% by spraying and maintained for 4-5 hours to allow the pollen of the mother plant to absorb water and swell and burst. Then, stop spraying and wait for the humidity to drop to 70-80%. Spray the flower spikes of the mother plant with nutrient stimulants and provide supplemental lighting for 2-6 hours.

[0009] The nutrient stimulants include 0.15-0.3 parts cytokinin, 15-21 parts pectin, 1-5 parts chitinase, 14-17 parts superphosphate, and 0.01-0.02 parts boric acid;

[0010] Male parent management: From the time the male parent is moved into the cultivation room, increase the light exposure by 2-3 hours per day, spray the male parent flower spikes with the microbial agent mentioned above every 7-10 hours, and spray the plant growth regulator one day before pollination;

[0011] (3) Artificial pollination: Place the male parent and the mother parent that have been managed before pollination in the same hybridization cage, with the male parent on top and the mother parent on the bottom. The bottom of the male parent's flower spike should be 3-5 cm away from the top of the mother parent's flower spike. When pollinating, gently shake the male parent to let the pollen fall onto the mother parent's flower spike. Shake the male parent for pollination once every hour from 8:00 to 11:00 every day until the mother parent's flowering is basically over. If the male parent's flowering period ends prematurely during this period, the male parent should be replenished in time.

[0012] (4) Post-pollination female parent culture: After pollination, remove the male parent and continue to culture the female parent for 20-40 days until the seeds mature, then it can be harvested.

[0013] Further, in step (1), the amount of microbial agent added is 5-8% of the weight of the root-promoting substrate.

[0014] Furthermore, in step (2), the temperature of the culture chamber is controlled at 25-30℃ and the relative humidity is controlled at 75-85%.

[0015] Further, in step (2), the parent nutrient solution is an aqueous solution containing 150-250 mg / L ammonium bicarbonate, 30-50 mg / L superphosphate, 250-330 mg / L potassium sulfate, 180-260 mg / L sucrose, 170-240 mg / L calcium nitrate, 3-3.5 mg / L boric acid, 20-40 mg / L fulvic acid, and 60-100 mg / L sodium silicate.

[0016] Further, in step (2), the nutrient solution for the parent plant is an aqueous solution containing 150-250 mg / L ammonium bicarbonate, 100-180 mg / L superphosphate, 250-330 mg / L potassium sulfate, 55-74 mg / L ferric sulfate, 30-42 mg / L zinc sulfate, 3-3.5 mg / L boric acid, 20-40 mg / L fulvic acid, and 60-100 mg / L sodium silicate.

[0017] Furthermore, in step (2), the nutrient stimulant is first diluted with water 1000-2000 times before spraying, and then sprayed until the flower spikes are moist.

[0018] Further, in step (2), the light used for the supplementary lighting process is red light and blue light, the intensity of the red light is 20000-30000 Lux, and the intensity of the blue light is 10000-15000 Lux.

[0019] Furthermore, in step (2), the microbial agent is first diluted with water 1000-2000 times before spraying, and then sprayed until the male parent's flower spike is moist.

[0020] Further, in step (2), the plant growth regulator is gibberellin, and the spraying concentration of gibberellin is 20-40 mg / L.

[0021] Furthermore, in step (3), the artificial pollination also includes controlling the temperature inside the hybridization cage to be 25-28°C and the relative humidity to be 70-80%.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention optimizes the cultivation of the male parent using microbial inoculants and nutrient solution, extending its flowering period and increasing pollen quantity and viability. It also optimizes the cultivation of the female parent using nutrient solution and reduces pollen viability by humidifying and cooling it before pollination, simultaneously stimulating female flower development. This extends the female parent's flowering period, improves the pollinationability of female flowers, significantly reduces the self-pollination rate of sugarcane, and increases hybridization efficiency. Using this method, the seed setting rate of hybrid sugarcane can be increased by 20-30%.

[0024] 2. In this invention, when planting the parent plants, a microbial inoculant is added to the root-promoting substrate of the male parent plant, and the microbial inoculant is sprayed on the male parent plant spikes every 7-10 hours. The soybean rhizobium, Bacillus subtilis, shortwave monoclonal bacteria, acetic acid bacteria, and lipogenic azospirobacter in the microbial inoculant work together to stimulate the male parent plant to produce hormones that are beneficial to root growth and pollen development, thereby promoting root development and pollen production. At the same time, the applicant found that increasing the daily light exposure in conjunction with the use of the microbial inoculant can prolong the flowering period of the male parent plant. In addition, the interaction of multiple elements such as phosphorus, iron, zinc, and boron in the nutrient solution of the male parent plant can prolong the flowering period of the male parent plant to about 7 days, increase the amount of pollen, improve pollen viability, and reduce the amount of male parent plant required.

[0025] 3. The raw materials of the nutrient solution for the female parent plant in this invention include nitrogen, phosphorus, potassium, calcium, silicon, boron, humic acid, sucrose, etc., which can stimulate the female parent plant to produce hormones that are beneficial to root growth and female flower development, thereby improving root development and the pollination capacity of female flowers. At the same time, this invention increases humidity and lowers temperature before pollination. The humidity is controlled at above 95% and maintained for 4-5 hours, which allows the pollen of the female parent plant to absorb water and swell and crack. The temperature is controlled at 8-12℃ and maintained for 6-8 hours, which reduces the activity of the pollen of the female parent plant and reduces the self-pollination rate. The use of nutrient stimulants combined with red and blue light supplemental lighting promotes the growth of the stigma of the female flower and increases the secretion of stigma mucus. This prevents the stigma mucus from being diluted by humidification treatment, which would reduce the adhesion of pollen grains. This achieves emasculation while improving the pollination capacity of female flowers.

[0026] 4. The cytokinins, pectin, superphosphate, and boric acid in the nutrient stimulants of this invention work together to promote the production of stigma mucus in female flowers, while chitinase helps pollen tubes penetrate the stigma and enter the style tissue, thus improving the pollination success rate. Detailed Implementation

[0027] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0028] The soybean rhizobium (Bradyrhizobium japonicum), Bacillus subtilis, Brevundimonas diminuta, Acetobacter ghanensis, and Azospirolum lipoferum mentioned below were all purchased from Ningbo Taisto Biotechnology Co., Ltd.

[0029] Example 1

[0030] A method for comprehensively improving the seed setting rate of sugarcane hybrid seeds includes the following steps:

[0031] (1) Parent planting: According to the hybridization plan, sugarcane parents are planted in spring. In the early stage of ear inoculation, rooting is carried out by wrapping the stem. The rooting is carried out by selecting 1-2 nodes in the upper part of the sugarcane stem and wrapping them with root-promoting substrate. The root-promoting substrate is mud or coconut coir with added root-promoting agent and wrapped with plastic film to promote root growth. Microbial inoculant of 5% of the weight of the root-promoting substrate is added to the root-promoting substrate of the male parent.

[0032] The microbial inoculants included 15 parts of Bradyrhizobium japonicum, 20 parts of Bacillus subtilis, 10 parts of Brevundimonas diminuta, 5 parts of Acetobacter ghanensis, and 8 parts of Azospirolum lipoferum.

[0033] (2) Pre-pollination management: When the parent plants have already produced spikes and the florets have begun to open, the parent plants are cut from the lower part of the bud for cultivation. The female plants are placed in the female nutrient solution for cultivation, and the male plants are placed in the male nutrient solution for cultivation. The female plants and male plants are placed in different cultivation rooms for cultivation. The temperature of the cultivation room is controlled at 25°C and the relative humidity is controlled at 80%.

[0034] The parent nutrient solution is an aqueous solution containing ammonium bicarbonate 150 mg / L, superphosphate 30 mg / L, potassium sulfate 250 mg / L, sucrose 180 mg / L, calcium nitrate 170 mg / L, boric acid 3 mg / L, humic acid 20 mg / L, and sodium silicate 60 mg / L.

[0035] The paternal nutrient solution is an aqueous solution containing ammonium bicarbonate 150 mg / L, superphosphate 100 mg / L, potassium sulfate 250 mg / L, ferric sulfate 55 mg / L, zinc sulfate 30 mg / L, boric acid 3 mg / L, humic acid 20 mg / L, and sodium silicate 60 mg / L.

[0036] Mother plant management: The mother plants are cooled down every night and then restored to normal culture temperature. The cooling treatment involves treating the mother plants at 8°C for 8 hours. The day before pollination, the humidity is controlled at above 95% by spraying for 4 hours to allow the pollen of the mother plants to absorb water and swell and burst. Spraying is then stopped, and when the humidity drops to 70%, nutrient stimulants are sprayed onto the flower spikes of the mother plants, followed by 2 hours of supplemental lighting. The supplemental lighting uses red and blue light, with the red light intensity at 20,000 Lux and the blue light intensity at 10,000 Lux.

[0037] The nutrient stimulant comprises 0.15 parts cytokinin, 15 parts pectin, 1 part chitinase, 14 parts superphosphate, and 0.01 parts boric acid. The nutrient stimulant should be diluted 1000 times with water before spraying until the flower spikes are moist.

[0038] Male parent management: From the time the male parent is moved into the culture room, increase the light exposure by 2 hours per day. Spray the male parent flower spikes with the microbial agent every 10 hours. Spray gibberellin one day before pollination. The concentration of gibberellin is 20 mg / L. When spraying the microbial agent, first dilute it with water 1000 times, and then spray until the male parent flower spikes are moist.

[0039] (3) Artificial pollination: Place the male parent and the mother parent that have been managed before pollination in the same hybridization cage. Control the temperature in the hybridization cage to 25℃ and the relative humidity to 75%. The male parent is on top and the mother parent is on the bottom. The bottom of the male parent's flower spike is 3cm away from the top of the mother parent's flower spike. When pollinating, gently shake the male parent to let the pollen fall onto the mother parent's flower spike. Shake the male parent for pollination once every hour from 8:00 am to 11:00 am every day until the mother parent's flowering is basically over. If the male parent's flowering period ends early during this period, the male parent should be replenished in time.

[0040] (4) Post-pollination female parent culture: After pollination, remove the male parent and continue to culture the female parent for 40 days until the seeds mature, then it can be harvested.

[0041] Example 2

[0042] A method for comprehensively improving the seed setting rate of sugarcane hybrid seeds includes the following steps:

[0043] (1) Parent planting: According to the hybridization plan, sugarcane parents are planted in spring. In the early stage of ear inoculation, rooting is carried out by wrapping the stem. The rooting is carried out by selecting 1 to 2 nodes in the upper part of the sugarcane stem and wrapping them with root-promoting substrate. The root-promoting substrate is mud or coconut coir with added root-promoting agent and wrapped with plastic film to promote root growth. Microbial inoculant of 8% of the weight of the root-promoting substrate is added to the root-promoting substrate of the male parent.

[0044] The microbial inoculants included 27 samples of *Bradyrhizobium japonicum*, 33 samples of *Bacillus subtilis*, 19 samples of *Brevundimonas diminuta*, 12 samples of *Acetobacter ghanensis*, and 15 samples of *Azospirolum lipoferum*.

[0045] (2) Pre-pollination management: When the parent plants have already produced spikes and the florets have begun to open, the parent plants are cut off from the lower part of the bud for cultivation. The female plants are placed in the female nutrient solution for cultivation, and the male plants are placed in the male nutrient solution for cultivation. The female plants and male plants are placed in different cultivation rooms for cultivation. The temperature of the cultivation room is controlled at 28°C and the relative humidity is controlled at 85%.

[0046] The parent nutrient solution is an aqueous solution containing ammonium bicarbonate 250 mg / L, superphosphate 50 mg / L, potassium sulfate 330 mg / L, sucrose 260 mg / L, calcium nitrate 240 mg / L, boric acid 3.5 mg / L, fulvic acid 40 mg / L, and sodium silicate 100 mg / L.

[0047] The paternal nutrient solution is an aqueous solution containing ammonium bicarbonate 250 mg / L, superphosphate 180 mg / L, potassium sulfate 330 mg / L, ferric sulfate 74 mg / L, zinc sulfate 42 mg / L, boric acid 3.5 mg / L, fulvic acid 40 mg / L, and sodium silicate 100 mg / L.

[0048] Mother plant management: Every evening, the mother plants are cooled down and then restored to normal culture temperature. The cooling treatment involves treating the mother plants at 12℃ for 6 hours. The day before pollination, the humidity is controlled at above 95% by spraying for 5 hours to allow the pollen of the mother plants to absorb water and swell and burst. Spraying is then stopped, and when the humidity drops to 80%, nutrient stimulants are sprayed onto the flower spikes of the mother plants, followed by 6 hours of supplemental lighting. The supplemental lighting uses red and blue light, with the red light intensity at 30,000 Lux and the blue light intensity at 15,000 Lux.

[0049] The nutrient stimulant comprises 0.3 parts cytokinin, 21 parts pectin, 5 parts chitinase, 17 parts superphosphate, and 0.02 parts boric acid. The nutrient stimulant should be diluted with water 2000 times before spraying until the flower spikes are moist.

[0050] Male parent management: From the time the male parent is moved into the culture room, increase the light exposure by 3 hours per day. Spray the male parent flower spikes with the microbial agent mentioned above every 10 hours. Spray gibberellin one day before pollination. The concentration of gibberellin sprayed is 40 mg / L. When spraying the microbial agent, first dilute it with water 2000 times, and then spray until the male parent flower spikes are moist.

[0051] (3) Artificial pollination: Place the male parent and the mother parent that have been managed before pollination in the same hybridization cage. Control the temperature in the hybridization cage to 28℃ and the relative humidity to 80%. The male parent is on top and the female parent is on the bottom. The bottom of the male parent's flower spike is 3cm away from the top of the female parent's flower spike. When pollinating, gently shake the male parent to let the pollen fall onto the female parent's flower spike. Shake the male parent for pollination once every hour from 8:00 am to 11:00 am every day until the female parent's flowering is basically over. If the male parent's flowering period ends early during this period, the male parent should be replenished in time.

[0052] (4) Post-pollination female parent culture: After pollination, remove the male parent and continue to culture the female parent for 40 days until the seeds mature, then it can be harvested.

[0053] Example 3

[0054] A method for comprehensively improving the seed setting rate of sugarcane hybrid seeds includes the following steps:

[0055] (1) Parent planting: According to the hybridization plan, sugarcane parents are planted in spring. In the early stage of ear inoculation, rooting is carried out by wrapping the stem. The wrapping rooting is to select 1-2 nodes in the upper part of the sugarcane stem and wrap them with the root-promoting substrate. The root-promoting substrate is mud or coconut coir with added root-promoting agent and wrapped with plastic film to promote root growth. Microbial inoculant of 7% of the weight of the root-promoting substrate is added to the root-promoting substrate of the male parent.

[0056] The microbial inoculants included 21 portions of *Bradyrhizobium japonicum*, 27 portions of *Bacillus subtilis*, 16 portions of *Brevundimonas diminuta*, 10 portions of *Acetobacter ghanensis*, and 11 portions of *Azospirolum lipoferum*.

[0057] (2) Pre-pollination management: When the parent plants have already produced spikes and the florets have begun to open, the parent plants are cut from the lower part of the bud for cultivation. The female plants are placed in the female nutrient solution for cultivation, and the male plants are placed in the male nutrient solution for cultivation. The female plants and male plants are placed in different cultivation rooms for cultivation. The temperature of the cultivation room is controlled at 25°C and the relative humidity is controlled at 82%.

[0058] The parent nutrient solution is an aqueous solution containing ammonium bicarbonate 190 mg / L, superphosphate 38 mg / L, potassium sulfate 310 mg / L, sucrose 240 mg / L, calcium nitrate 200 mg / L, boric acid 3.2 mg / L, fulvic acid 33 mg / L, and sodium silicate 75 mg / L.

[0059] The paternal nutrient solution is an aqueous solution containing ammonium bicarbonate 190 mg / L, superphosphate 145 mg / L, potassium sulfate 310 mg / L, ferric sulfate 67 mg / L, zinc sulfate 37 mg / L, boric acid 3.2 mg / L, fulvic acid 33 mg / L, and sodium silicate 75 mg / L.

[0060] Mother plant management: The mother plants are cooled down every night and then restored to normal culture temperature. The cooling treatment involves treating the mother plants at 10℃ for 7 hours. On the day before pollination, the humidity is controlled at above 95% by spraying for 4.5 hours to allow the pollen of the mother plants to absorb water and swell and burst. Spraying is then stopped, and when the humidity drops to 75%, nutrient stimulants are sprayed onto the flower spikes of the mother plants, followed by 4 hours of supplemental lighting. The supplemental lighting uses red and blue light, with the red light intensity at 25,000 Lux and the blue light intensity at 12,000 Lux.

[0061] The nutrient stimulant comprises 0.2 parts cytokinin, 18 parts pectin, 3 parts chitinase, 15 parts superphosphate, and 0.01 parts boric acid. The nutrient stimulant should be diluted with water 1500 times before spraying until the flower spikes are moist.

[0062] Male parent management: From the time the male parent is moved into the culture room, increase the light exposure by 2.5 hours per day. Spray the male parent flower spikes with the microbial agent mentioned above every 9 hours. Spray gibberellin one day before pollination. The concentration of gibberellin sprayed is 30 mg / L. When spraying the microbial agent, first dilute it with water 1500 times, and then spray until the male parent flower spikes are moist.

[0063] (3) Artificial pollination: Place the male parent and the mother parent that have been managed before pollination in the same hybridization cage. Control the temperature in the hybridization cage to 26℃ and the relative humidity to 70%. The male parent is on top and the mother parent is on the bottom. The bottom of the male parent's flower spike is 3cm away from the top of the mother parent's flower spike. When pollinating, gently shake the male parent to let the pollen fall onto the mother parent's flower spike. Shake the male parent for pollination once every hour from 8:00 am to 11:00 am every day until the mother parent's flowering is basically over. If the male parent's flowering period ends early during this period, the male parent should be replenished in time.

[0064] (4) Post-pollination female parent culture: After pollination, remove the male parent and continue to culture the female parent for 40 days until the seeds mature, then it can be harvested.

[0065] Comparative Example 1: In step (1), no microbial agent was added to the root-promoting substrate of the male parent, and the other steps were the same as in Example 1.

[0066] Comparative Example 2: In step (2), conventional nutrient solution (sulfurous acid solution) was used instead of the maternal and paternal nutrient solutions for cultivation, and the other steps were the same as in Example 1.

[0067] Comparative Example 3: There are no parent plant management measures in step (2), and the other steps are the same as in Example 1.

[0068] Comparative Example 4: In step (2), when managing the parent plant, the humidity is not controlled to above 95% the day before pollination, and the other steps are the same as in Example 1.

[0069] Comparative Example 5: In step (2), when managing the mother plant, no nutrient stimulant is sprayed on the mother plant flower spikes, and the other steps are the same as in Example 1.

[0070] Comparative Example 6: In step (2), no supplemental lighting was applied during the management of the parent plant, and the other steps were the same as in Example 1.

[0071] Comparative Example 7: There is no parent management measure in step (2), and the other steps are the same as in Example 1.

[0072] Comparative Example 8: In step (2), when managing the male parent, no microbial agents and gibberellins are sprayed on the male parent flower spikes, and the other steps are the same as in Example 1.

[0073] Comparative Example 9: Hybridization was performed using conventional methods, the specific steps of which are as follows:

[0074] (1) Parent planting: According to the hybridization plan, sugarcane parents are planted in spring. During the early stage of spikelet inoculation, rooting is carried out by wrapping the stem. The wrapping rooting involves selecting 1 to 2 nodes in the upper part of the sugarcane stem and wrapping them with a root-promoting substrate. The root-promoting substrate is mud or coconut coir with added root-promoting agent and wrapped with plastic film to promote root growth.

[0075] (2) Collection and cultivation of flower spikes: When the parent plants have produced spikes and the florets have begun to open, the parent plants are cut from the lower part of the bud and transferred to the hybridization chamber. They are then placed in a sulfurous acid solution for cultivation. The male parent and the female parent are placed in the same hybridization cage, with the male parent on top and the female parent on the bottom. The bottom of the male parent's flower spike is 4 cm away from the top of the female parent's flower spike. Before pollination, the male parent and the female parent are covered with isolation cloth. The temperature of the hybridization chamber is controlled at 25℃ and the relative humidity is 83%.

[0076] (3) Artificial pollination: When pollinating, gently shake the male parent to scatter the pollen onto the female parent's flower spike. Shake the male parent every hour from 8:00 to 10:00 every day until the female parent's flowering is basically over. If the male parent's flowering period ends prematurely, the male parent should be supplemented in time. The temperature in the hybridization room should be controlled at 25℃ and the relative humidity at 80%.

[0077] (4) Post-pollination female parent culture: After pollination, remove the male parent and continue to culture the female parent until the seeds mature and are harvested.

[0078] The seeds harvested from each embodiment were sun-dried for 7 days to promote after-ripening, and then placed in a low-temperature, dry environment for 20 days to induce seed revival. In March 2023, the seeds from each embodiment were sown in perforated seedling trays (petries with filter paper). Before sowing, 20-30 seeds were counted and sown in one petri dish, and the trays were kept at 28-30℃.

[0079] After germination and cultivation in an incubator, seedling emergence was recorded once the seedlings reached a height of 2-3 cm. The hybrid seed setting rate was calculated as follows: Hybrid seed setting rate = (Number of seedlings / Total number of seeds) × 100%. The results are shown in Table 1.

[0080] Table 1. Fruit set rate of each embodiment

[0081] Group Seed setting rate of hybrid varieties (%) Example 1 77 Example 2 79 Example 3 82 Comparative Example 1 72 Comparative Example 2 70 Comparative Example 3 61 Comparative Example 4 63 Comparative Example 5 64 Comparative Example 6 66 Comparative Example 7 67 Comparative Example 8 69 Comparative Example 9 57

[0082] The table above shows that compared with conventional hybridization methods (Comparative Example 9), the method of the present invention can increase the seed setting rate of sugarcane hybrid seeds by 20-25%. Specifically, replacing the conventional nutrient solution (sulfurous acid solution) with the nutrient solution of the female and male parents can improve the seed setting rate. Furthermore, applying microbial agents to the male parent during planting, and performing pre-pollination management on the female parent (humidifying the female parent, spraying with nutrient stimulants, and supplementing with light before pollination), and performing pre-pollination management on the male parent (increasing light exposure, spraying the male parent's flower spikes with microbial agents and gibberellins) can all improve the seed setting rate of hybrid seeds.

[0083] The applicant also measured and counted the number and length of roots of individual male plants in Examples 1, 2, 3, Comparative Examples 1, and 2 the day before pollination, and measured and counted the number and length of roots of individual female plants in Examples 1, 2, 3, and 2. The average value of 5 plants in each group was taken. The results are shown in Table 2.

[0084] Table 2 Comparison of root growth in each group

[0085]

[0086] Table 2 shows that microbial inoculants and fertilization solutions for the male parent plant can promote root development, while fertilization solutions for the female parent plant can promote root development. Combined with Table 1, it can be seen that good root development and strong nutrient absorption capacity of the plant result in a high pollination success rate and a high seed setting rate for hybrid seeds.

[0087] In addition, the applicant found that the flowering period of the parent plants in Examples 1 to 3 is 7-8 days, and only 1-2 male flower spikes are needed to pollinate one female flower spike, while conventional (comparative Example 9) requires 4 male flower spikes to complete pollination. Therefore, the method of the present invention reduces the amount of male flower spikes used.

[0088] In summary, this invention optimizes the cultivation of the male parent using microbial agents and nutrient solution, thereby extending its flowering period and increasing pollen quantity and viability. It also optimizes the cultivation of the female parent using nutrient solution and humidifies it before pollination to reduce pollen viability, while simultaneously stimulating female flower development. This extends the female parent's flowering period, improves the pollinationability of female flowers, significantly reduces the self-pollination rate of sugarcane, and increases hybridization efficiency. Furthermore, this method can increase the seed setting rate of hybrid sugarcane seeds by 20-30%.

[0089] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for comprehensively improving the seed setting rate of sugarcane hybrid seeds, characterized in that, Includes the following steps: (1) Parent planting: According to the hybridization plan, sugarcane parents are planted in spring. In the early stage of ear incubation, rooting is carried out by wrapping the stem. The wrapping rooting involves selecting 1-2 nodes in the upper part of the sugarcane stem and wrapping them with a root-promoting substrate. The root-promoting substrate is mud or coconut coir with added root-promoting agent and wrapped with plastic film to promote root growth. Microbial agents are added to the root-promoting substrate of the male parent. The microbial inoculant includes 15-27 parts of soybean rhizobium, 20-33 parts of Bacillus subtilis, 10-19 parts of shortwave monocytogenes, 5-12 parts of acetic acid bacteria, and 8-15 parts of lipogenic nitrogen-fixing spirochetes. (2) Pre-pollination management: When the parent plants have already produced spikes and the florets have begun to open, the parent plants are cut off from the lower part of the bud for cultivation. The female plants are placed in the female nutrient solution for cultivation, and the male plants are placed in the male nutrient solution for cultivation. The female plants and male plants are placed in different cultivation rooms for cultivation. Mother plant management: Every night, the mother plant is cooled down and then restored to the normal culture temperature. The cooling treatment is to treat the mother plant at 8-12℃ for 6-8 hours. On the day before pollination, the humidity is controlled at above 95% by spraying and maintained for 4-5 hours to allow the pollen of the mother plant to absorb water and swell and burst. Then, stop spraying and wait for the humidity to drop to 70-80%. Spray the flower spikes of the mother plant with nutrient stimulants and provide supplemental lighting for 2-6 hours. The nutrient stimulants include 0.15-0.3 parts cytokinin, 15-21 parts pectin, 1-5 parts chitinase, 14-17 parts superphosphate, and 0.01-0.02 parts boric acid; Male parent management: From the time the male parent is moved into the cultivation room, increase the light exposure by 2-3 hours per day, spray the male parent flower spikes with the microbial agent mentioned above every 7-10 hours, and spray the plant growth regulator one day before pollination; (3) Artificial pollination: Place the male parent and the mother parent that have been managed before pollination in the same hybridization cage, with the male parent on top and the mother parent on the bottom. The bottom of the male parent's flower spike should be 3-5 cm away from the top of the mother parent's flower spike. When pollinating, gently shake the male parent to let the pollen fall onto the mother parent's flower spike. Shake the male parent for pollination once every hour from 8:00 to 11:00 every day until the mother parent's flowering is basically over. If the male parent's flowering period ends prematurely during this period, the male parent should be replenished in time. (4) Post-pollination female parent culture: After pollination, remove the male parent and continue to culture the female parent for 20-40 days until the seeds mature, then it can be harvested.

2. The method for comprehensively improving the seed setting rate of sugarcane hybrid seeds according to claim 1, characterized in that, In step (1), the amount of microbial agent added is 5-8% of the weight of the root-promoting substrate.

3. The method for comprehensively improving the seed setting rate of sugarcane hybrid seeds according to claim 1, characterized in that, In step (2), the temperature of the culture chamber is controlled at 25-30℃ and the relative humidity is controlled at 75-85%.

4. The method for comprehensively improving the seed setting rate of sugarcane hybrid seeds according to claim 1, characterized in that, In step (2), the parent nutrient solution is an aqueous solution containing 150-250 mg / L ammonium bicarbonate, 30-50 mg / L superphosphate, 250-330 mg / L potassium sulfate, 180-260 mg / L sucrose, 170-240 mg / L calcium nitrate, 3-3.5 mg / L boric acid, 20-40 mg / L fulvic acid, and 60-100 mg / L sodium silicate.

5. The method for comprehensively improving the seed setting rate of sugarcane hybrid seeds according to claim 1, characterized in that, In step (2), the nutrient solution for the male parent is an aqueous solution containing 150-250 mg / L ammonium bicarbonate, 100-180 mg / L superphosphate, 250-330 mg / L potassium sulfate, 55-74 mg / L ferric sulfate, 30-42 mg / L zinc sulfate, 3-3.5 mg / L boric acid, 20-40 mg / L fulvic acid, and 60-100 mg / L sodium silicate.

6. The method for comprehensively improving the seed setting rate of sugarcane hybrid seeds according to claim 1, characterized in that, In step (2), the nutrient stimulant is first diluted with water 1000-2000 times before spraying, and then sprayed until the flower spikes are moist.

7. The method for comprehensively improving the seed setting rate of sugarcane hybrid seeds according to claim 1, characterized in that, In step (2), the supplementary lighting process uses red light and blue light, with the red light intensity being 20,000-30,000 Lux and the blue light intensity being 10,000-15,000 Lux.

8. The method for comprehensively improving the seed setting rate of sugarcane hybrid seeds according to claim 1, characterized in that, In step (2), the microbial agent is first diluted with water 1000-2000 times before spraying, and then sprayed until the male parent's flower spike is moist.

9. The method for comprehensively improving the seed setting rate of sugarcane hybrid seeds according to claim 1, characterized in that, In step (2), the plant growth regulator is gibberellin, and the spraying concentration of gibberellin is 20-40 mg / L.

10. The method for comprehensively improving the seed setting rate of sugarcane hybrid seeds according to claim 1, characterized in that, In step (3), the artificial pollination also includes controlling the temperature inside the hybridization cage to be 25-28℃ and the relative humidity to be 70-80%.

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