NL2029503B1

NL2029503B1 - Hybrid seed production method based on subgynoecious cucumber as female parent

Info

Publication number: NL2029503B1
Application number: NL2029503A
Authority: NL
Inventors: Tang Xinying; Wang Xue; Cheng Lin; Li Xiaojie; Qiu Zhijun; Wei Meitian
Original assignee: Shandong Shouguang Vegetable Seed Ind Group Co Ltd; Shandong Shouguang Vegetable Ind Group Co Ltd
Priority date: 2021-06-22
Filing date: 2021-10-25
Publication date: 2022-04-29
Also published as: NL2029503A; CN113243292A

Abstract

The present disclosure provides a hybrid seed production method based on subgynoecious cucumber as a female parent, and belongs to the technical field of hybrid seed production of cucumber. The method includes the following steps: step l, sowing seeds of a female parent 4—6 days after sowing seeds of a male parent, step 2, conducting a first male flower inducing treatment with silver nitrate solution at one-leaf-one-bud seedling stage of the male parent, and after 3—5 days, conducting a second male flower inducing treatment; step 3, picking a male flower bloomed on the day, applying a part where petals are removed from the male flower to stigmas of a female flower, and performing pollination by closure of petals of the female flower, and step 4, pollinating and retaining fruits from the 12th leaf of a plant, successively pollinating and retaining 2—4 fruits, removing all female flowers at nodes 5—7 above a last fruit node to be successively pollinated and retained, pollinating and retaining a last fruit upon the blossom of female flowers at nodes 6—8 above the last fruit node successively retained after pollination, and removing all unpollinated female flowers. The method of the present disclosure may improve seed yield and quality.

Description

HYBRID SEED PRODUCTION METHOD BASED ON SUBGYNOECIOUS CUCUMBER AS FEMALE PARENT TECHNICAL FIELD

[01] The present disclosure belongs to the technical field of hybrid seed production of cucumber, and particularly relates to a hybrid seed production method based on subgynoecious cucumber as a female parent.

BACKGROUND ART

[02] Cucumber (Cucumis sativus 1.) is an annual scandent or creeping herb of the family Cucurbitaceae. It is also known as hugua (literally foreign gourd) or qinggua (literally green gourd). Its stems and branches are elongated, angular and with white rough trichomes on the surface. Tendrils are slender. Petioles are asperous and hispid. Leaf blades are broadly ovate-cordate and membranous; lobes are triangular and dentate. It is widely cultivated throughout China, and planted in greenhouses or vinylhouses of many regions; it is now widely planted in temperate and tropical regions. Cucumber is one of the main summer vegetables throughout China. Seed production technique of cucumber influences the quality and yield of commercial cucumber seeds, which has a critical effect on cucumber cultivation. At present, subgynoecious cucumber has problems of low seed yield and low seed plumpness during the seed production.

SUMMARY

[03] In view of this, an objective of the present disclosure is to provide a hybrid seed production method based on subgynoecious cucumber as a female parent. The method features high pollination efficiency and quality, invulnerability to plant presenility, and capacity of ensuring normal ripening of stock fruits, thereby increasing seed yield and quality, benefits to farmers, and germination percentage and germination potential of commercial seeds.

[04] To achieve the above objective, the present disclosure provides the following technical solution:

[05] The present disclosure provides a hybrid seed production method based on subgynoecious cucumber as a female parent, including the following steps:

[06] step 1, sowing seeds of a female parent 4-6 days after sowing seeds of a male parent, where the seeds of the male and female parents have a quantitative ratio of 1:(4-6);

[07] step 2, conducting a first male flower inducing treatment with silver nitrate solution at a one-leaf-one-bud seedling stage of the male parent, and after 3-5 days, conducting a second male flower inducing treatment with silver nitrate solution;

[08] step 3, picking a male flower bloomed on the day, applying a part where petals are removed from the male flower to stigmas of a female flower, and performing pollination by closure of petals of the female flower; and

[09] step 4, pollinating and retaining fruits from the 12! leaf of a plant, successively pollinating and retaining 2—4 fruits, removing all female flowers at nodes 5-7 above a last fruit node successively retained after pollination, pollinating and retaining a last fruit upon the blossom of female flowers at nodes 6 to 8 above the last fruit node successively retained after pollination, and removing all unpollinated female flowers.

[10] Preferably, the pollination in step 3 may be conducted at 8:00 to 12:00 a.m. on a fine day, and the pollination may be conducted at a temperature of >20°C.

[11] Preferably, each male flower in step 3 may pollinate a female flower.

[12] Preferably, the closure of petals of the female flower in step 3 may be achieved by wrapping up and clamping the petals of the female flower with grafting clips.

[13] Preferably, sowing time may be from mid-February to mid-April when the method is implemented in the Huang-Huai-Hai Region, China.

[14] Preferably, the silver nitrate solution in step 2 may have a concentration of

0.25-0.35 g/kg.

[15] Preferably, farming management may be conducted during the hybrid seed production.

[16] Preferably, the farming management may include application of a base fertilizer before field planting, soil disinfection, water and fertilizer management at a seedling stage, application of nitrogen and potassium fertilizers after pollination and inflation of fruitlets, field separation, and pest and disease control.

[17] Preferably, the pest and disease may include Fusarium wilt, downy mildew, damage by thrips, and damage by aphids.

[18] Preferably, topping off may not be conducted after the pollination in step 3.

[19] Beneficial effects: Through the control of sowing interval time, the male flower inducing treatment of the male parent, the closed pollination, and the retaining of 3-5 fruits, the hybrid seed production method based on subgynoecious cucumber as a female parent provided by the present disclosure improves pollination efficiency and quality. Thus, stock plants are invulnerable to plant presenility, so as to ensure normal ripening of stock fruits and solve the problems of low yield and plumpness of seeds obtained by seed production of subgynoecious cucumber. The method may significantly increase seed yield and quality, benefits to farmers, and germination percentage and germination potential of commercial seeds.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[20] The present disclosure provides a hybrid seed production method based on subgynoecious cucumber as a female parent, including the following steps: step 1, sowing seeds of a female parent 4—6 days after sowing seeds of a male parent, where the sown seeds of the male and female parents have a quantitative ratio of 1:(4—6); step 2, conducting a first male flower inducing treatment with silver nitrate solution at one-leaf-one-bud seedling stage of the male parent, and after 3—5 days, conducting a second male flower inducing treatment with silver nitrate solution; step 3, picking a male flower bloomed on the day, applying a part where petals are removed from the male flower to stigmas of a female flower, and performing pollination by closure of petals of the female flower; and step 4, pollinating and retaining fruits from the 12 leaf of a plant, successively pollinating and retaining 2—4 fruits, removing all female flowers at nodes 5-7 above a last fruit successively retained after pollination, pollinating and retaining a last fruit upon the blossom of female flowers at nodes 6-8 above the last fruit node successively retained after pollination, and removing all unpollinated female flowers.

[21] In the present disclosure, seeds of a female parent are sown 4-6 days after seeds of a male parent are sown, where the seeds of the male and female parents have a quantitative ratio of 1:(4-6). Sowing time of the seeds of the male parent is not particularly limited in the present disclosure and determined according to the sowing region; the sowing time may preferably be from mid-February to mid-April when the method is implemented in the Huang-Huai-Hai Region, China. Specifically, the male parent may be sown in mid-February when the male and female parents are sown in a greenhouse; and the male parent may be sown in mid-April when the male and female parents are sown in a vinylhouse. In the specific implementation of the present disclosure, the seeds of the female parent may preferably be sown 5 days after the seeds of the male parent are sown; the seeds of the male and female parents may preferably have a quantitative ratio of 1:5. In the present disclosure, the seeds of the female parent may preferably have a row spacing of (24-25) x (64-66) cm, and more preferably 25 x 65 cm. In the present disclosure, the male parent may be a homozygous higher-generation material, and CUF001 may preferably be a cultivar of the male parent; the male parent may preferably have a row spacing of 25 x 60 cm. In the present disclosure, the female parent may be separated from the male parent, and either parent may be planted in a different plot. In the present disclosure, field planting quantity of the male parent may preferably be 750-850 plants/mu, and more preferably 800 plants/mu; that of the female parent may preferably be 3,500-4,500 plants/mu, and more preferably 4,000 plants/mu. In the present disclosure, the female parent may preferably be a subgynoecious cucumber cultivar, such as Shouyou 60 and Shouyan

101.

[22] In the present disclosure, a first male flower inducing treatment is conducted with silver nitrate solution at a one-leaf-one-bud seedling stage of the male parent, and after 3-5 days, a second male flower inducing treatment is conducted with silver nitrate solution. In the present disclosure, the silver nitrate solution may preferably have a concentration of 0.25-0.35 g/kg, more preferably 0.28-0.32 g/kg, and most preferably 0.3 g/kg. In the present disclosure, the second male flower inducing treatment may preferably be conducted at 3-day intervals after the first male flower inducing treatment, specific operations of the male flower inducing treatment are not particularly limited in the present disclosure, and conventional operations of the male flower inducing treatment in the art may be used.

[23] In the present disclosure, the pollination is conducted when the female parent grows more than 12 leaves; specifically, the pollination is conducted as follows: picking a male flower bloomed on the day, applying a part where petals are removed trom the male flower to stigmas of a female flower, and performing pollination by closure of petals of the female flower. In the present disclosure, the pollination may preferably be conducted at 8:00 to 12:00 a.m. on a fine day; on cloudy and rainy days, the pollination may preferably be appropriately delayed. In the present disclosure, the pollination may preferably be conducted at a temperature of 20-25°C. In the present disclosure, the male flower may preferably be a male flower with bright yellow petals and strong pollen viability; in the present disclosure, each male flower may preferably pollinate a female flower to ensure sufficient pollination. In the present disclosure, the pollinated male flower may preferably lean on a stigma of the female flower, followed 5 by closure of petals of the female flower; the closure of petals of the female flower may preferably be achieved by bunddling and clamping the petals of the female flower with grafting clips.

[24] In the present disclosure, pollination and fruits retaining are conducted from the 12™ leaf of a plant, and 2—4 fruits are successively retained after pollination, followed by removal of all female flowers at nodes 5 to 7 above the last fruit node successively retained after pollination; upon the blossom of female flowers at nodes 6—8 above the last fruit node successively retained after pollination, a last fruit is retained after pollination., and all unpollinated female flowers are removed. In the present disclosure, it may be preferable to ensure that each plant retains 3—5 and more preferably 4 pollinated fruits. In the specific implementation of the present disclosure, it may be preferable to successively retain 3 fruits and remove all female flowers at node 6 above the last fruit node successively retained after pollination; upon the blossom of female flowers at node 7 above the last fruit node successively retained after pollination, the last fruit is retained after pollination, while all unpollinated female flowers are removed from the plant.

[25] In the present disclosure, farming management may be conducted during the hybrid seed production. Preferably, the farming management may preferably include application of a base fertilizer before field planting, soil disinfection, water and fertilizer management at a seedling stage, application of nitrogen and potassium fertilizers after pollination and inflation of fruitlets, field separation, and pest and disease control. In the present disclosure, during the downdressing before setting, base manure may preferably be rotten chicken manure. The application amount of the base fertilizer may preferably be 1.5-3 tons/mu, and more preferably 2 tons/mu; the soil disinfection may preferably be implemented by soil fumigation; the water and fertilizer management at the seedling stage may preferably include application of 200 mL/m: humic acid-containing water-soluble fertilizer (active rooting agent) in watering roots after seedling recovery. In the present disclosure, it may be preferably not to fertigate before pollination, but to apply nitrogen and potassium fertilizers after pollination and inflation of fruitlets; the nitrogen and potassium fertilizers may preferably be high nitrogen and potassium fertilizers, and specifically macroelement water-soluble fertilizers. The nitrogen and potassium fertilizers may preferably be fertigated, the nitrogen and potassium fertilizers may preferably be fertigated twice or thrice, and the amount thereof may preferably be 20 kg/mu per fertigation, the nitrogen and potassium fertilizers may play a role in ensuring nutrient requirements for plant growth and inflation of fruitlets. In the present disclosure, the pest and disease may include Fusarium wilt, downy mildew, damage by thrips, and damage by aphids. Methods for controlling the pest and disease are not particularly limited in the present disclosure, and a conventional method for controlling the pest and disease in the art may be adopted. In the present disclosure, throughout the hybrid seed production process, it may be preferable to implement field separation measures to prevent insect pollination; in the present disclosure, it may be preferable to implement separation at the exit/entrance and air inlet/outlet of a planting area using >40 mesh gauzes, so as to prevent pollinating insects from entering. In the present disclosure, to ensure enough leaves to produce nutrients to supply stock fruits for growth and ripening, topping off may not be conducted after the pollination.

[26] By adopting the method provided by the present disclosure, average seed yield per plant is over 500 seeds. High yield of a total of over 50 kg/m may be obtained.

[27] The technical solution provided by the present disclosure will be described in detail below with reference to examples, but the examples should not be construed as limiting the protection scope of the present disclosure.

[28] Example 1

[29] In spring 2019, hybrid seed production of subgynoecious cucumber Shouyou 60 was conducted in the greenhouse of the breeding base of the Daxihuan Industrial Park, Shouguang, Shandong Province. Separation was implemented at the exit/entrance and air inlet/outlet of a planting area using >40 mesh gauzes, so as to prevent pollinating insects from entering; sufficient base fertilizer was applied and pest and diseases were prevented timely.

[30] The male and female parents were planted on February 10 and February 15, respectively; 1,600 male parents were planted, and 8,000 female parents were planted. The male parents were subjected to the first male flower inducing treatment with 0.3 g/kg silver nitrate solution at the one-leaf-one-bud seedling stage, namely 1,600 male parents were treated with 1.2 g of silver nitrate. A second spray of the same concentration of silver nitrate solution was done after three days.

[31] On March 25, cross pollination started from the 12 leaf of the plant. In order to ensure that male flowers bloomed normally and pollens were viable, the pollination time was selected to be at 8:00 to 12:00 a.m. on sunny days and appropriately delayed on cloudy and rainy days. The temperature was guaranteed to be at 20—28°C, in case that the temperature was too low to disseminate pollens. During the pollination, a male flower with bright yellow petals that bloomed on the day was selected, the petals were removed, and the stigmas of the female flower was aligned for application; after that, the male flower was leaned on the stigmas, and the petals of the female flower were wrapped up and clamped with round grafting clips, so that the male flower was left in the female flower. One male flower only pollinated a female flower, ensuring sufficient pollination. Fruits were pollinated and retained from the 11 leaf of a plant. Three fruits could be successively retained after pollination. All female flowers at node 5 above the retained fruit node were removed; after female flowers at node 6 and above thereabove bloomed, the last fruit was retained after pollination, and all unpollinated female flowers were removed from the plant, ensuring that finally there were four pollinated fruits per plant.

[32] Seeds were harvested since May 10, and the cleaning, sun-drying, and impurity removal of all seeds were completed on June 1. The seed quality and yield were detected.

[33] The specific detection method was as follows:

[34] Harvested Shouyou 60 test group and control group were divided into three groups, respectively. Each group contained 100 seeds, which were sown in 100-hole or 50-hole plug trays and managed according to the conventional seedling raising method. Germination of each group was recorded after 10 days, and germination percentage was calculated. The calculation formula was as follows: germination percentage % = number of germinated seeds/100.

[35] Germination potential: The number of germinated seeds of each group was recorded at 5 days after sowing, during which the germination potential was the percentage of the number of germinated seeds to the number of all seeds. The calculation formula was as follows: germination potential % = number of germinated seeds at 5 days/100. Specific results are shown in Tables 1 and 2.

[36] Table 1 The comparison of the quality of hybrid seeds of Shouyou 60 Test Thousand-grain |Germination Germination plot eight (g) potential percentage Plot

28.5 95% 97% T1 Plot Test group (T) - 29 94% 96% Plot

29.5 96% 98% T3 Conventional control group (CK)

[37] Table 2 The comparison of the yield of hybrid seeds of Shouyou 60 Test Yield per (Average yield Average income increase plot u (kg) per mu (kg) per mu (yuan) Plot 53 T1 | Plot | | Test group (T) 56 56 6,400 T2 Plot 59 T3 Conventional control ce group (CK) CK [0

[38] According to the detection, the seed plumpness was high, the thousand-grain weight reached 29 g, and the seed yield per 724 reached 56 kg/m. According to conventional seed production operations, the thousand-grain weight of the cultivar was 25-27 g, and the yield was 30-40 kg; according to this production technology, the seed quality and yield were increased significantly, the yield per mu was more than 16 kg, and the yield was increased by more than 40%; based on the seed production cost of RMB 400 yuan/kg, the income of seed production was increased by more than 6,400 yuan/mu.

[39] Example 2

[40] In spring 2020, hybrid seed production of subgynoecious cucumber Shouyan 101 was conducted in the greenhouse of the Luocheng base of the Shouguang Vegetable Industry Holding Group Co., Ltd., Shandong Province. Separation was implemented at the exit/entrance and air inlet/outlet of a planting area using >40 mesh gauzes, so as to prevent pollinating insects from entering; sufficient base fertilizer was applied and pest and diseases were prevented timely.

[41] The male and female parents were set on February 11 and February 16, respectively; 800 male parents were planted, and 4,000 female parents were planted.

The male parents were subjected to the first male flower inducing treatment with 0.3 g/kg silver nitrate solution at the one-leaf-one-bud seedling stage of the seedling stage, namely 1,600 male parents were treated with 1.2 g of silver nitrate. A second spray of the same concentration of silver nitrate solution was done after three days.

[42] On March 27, cross pollination started from the 12 leaf of a plant. The pollination was selected to conduct at 8:00 to 12:00 a.m. on sunny days and appropriately delayed on cloudy and rainy days. The temperature of at least 20-25°C could guarantee that the male flower bloomed normally and pollens were viable. During the pollination, a male flower with bright yellow petals that bloomed on the day was selected, the petals were removed, and the stigmas of the female flower was aligned for application; after that, the male flower was leaned on the stigmas, and the petals of the female flower were wrapped up and clamped with round grafting clips, so that the male flower was left in the female flower. One male flower only pollinated a female flower, ensuring sufficient pollination. Fruits were pollinated and retained from the 12% leaf of a plant. Three fruits could be successively retained after pollination. All female flowers at node 6 above the 3™ fruit were removed; after female flowers at node 7 and above thereabove bloomed, the last fruit was retained after pollination, and all unpollinated female flowers were removed from the plant, ensuring that finally there were four stock fruits per plant.

[43] Seeds were harvested since May 12, and the cleaning, sun-drying, and impurity removal of all seeds were completed on June 5. The seed quality and yield were detected.

[44] A specific detection method was as follows:

[45] Harvested Shouyan 101 test group and control group were divided into three groups, respectively. Each group contained 100 seeds, which were sown in 100-hole or 50-hole plug trays and managed according to the conventional seedling raising method. Germination of each group was recorded after 10 days, and germination percentage was calculated. The calculation formula was as follows: germination percentage % = number of germinated seeds/100.

[46] Germination potential: The number of germinated seeds of each group was recorded at 5 days after sowing, during which the germination potential was the percentage of the number of germinated seeds to the number of all seeds. The calculation formula was as follows: germination potential % = number of germinated seeds at 5 days/100.

[47] Detection results are shown in Tables 3 and 4.

[48] Table 3 The comparison of the quality of hybrid seeds of Shouyan 101 Test Thousand-grain |Germination Germination plot weight (g) potential percentage Plot

31.4 96% 98% T1 Plot Test group (T) 29.6 95% 97% T2 Plot 32 96% 98% T3 Conventional control | ck2prs pw group (CK) ee] CRs pes PI

[49] Table 4 The comparison of the yield of hybrid seeds of Shouyan 101 Test |Yield per (Average yield Average income increase plot |mu (kg) per mu (kg) per mu (yuan) Plot 63 Tl Plot Test group (T) T2 65 63 7,200 Plot 61 T3 meh — Conventional control ck2ps group (CK) Ef

[50] According to the detection, the seed plumpness was high, the thousand-grain weight reached 31 g, and the seed yield per mu reached 63 kg/m. According to according to conventional seed production operations, the thousand-grain weight of the cultivar was 28 g, and the yield was 42-48 kg; according to this production technology, the seed quality and yield were increased significantly, the yield per mu was more than 18 kg, and the yield was increased by more than 40%; based on the seed production cost of RMB 400 vuan/kg, the income of seed production was increased by more than 7,200 vuan/mu.

[51] Example 3

[52] In spring 2020, hybrid seed production of gynoecious cucumber Cuimei No. 1 was conducted in the vinylhouse of the Luocheng base of the Shouguang Vegetable Industry Holding Group Co., Ltd., Shandong Province. Separation was implemented at the exit/entrance and air inlet/outlet of a planting area using >40 mesh gauzes, so as to prevent pollinating insects from entering; sufficient base fertilizer was applied and pest and diseases were prevented timely. [S3] The male and female parents were planted on April 12 and April 17, respectively; 800 male parents were planted, and 4,000 female parents were planted. The male parents were subjected to the first male flower inducing treatment with 0.3 g/kg silver nitrate solution at the one-leaf-one-bud seedling stage of the seedling stage, namely 1,600 male parents were treated with 1.2 g of silver nitrate. A second spray of the same concentration of silver nitrate solution was done after three days. [S4] On May 25, cross pollination started. The pollination was selected to conduct at 7:00 to 12:00 a.m. on sunny days and appropriately delayed on cloudy and rainy days. The temperature was guaranteed to be at 20-30°C to prevent inactivation of pollens due to excessively high temperature. During the pollination, a male flower with bright yellow petals that bloomed on the day was selected, the petals were removed, and the stigmas of the female flower was aligned for application; after that, the male flower was leaned on the stigmas, and the petals of the female flower were wrapped up and clamped with round grafting clips, so that the male flower was left in the female flower. One male flower only pollinated a female flower, ensuring sufficient pollination. Fruits were pollinated and retained from the 13% leaf of a plant. Three fruits could be successively retained after pollination. All female flowers at node 6 above the retained fruit node were removed; after female flowers at node 7 and above thereabove bloomed, the last fruit was retained after pollination, and all unpollinated female flowers were removed from the plant, ensuring that finally there were four pollinated stock fruits per plant.

[55] Seeds were harvested since July 10, and the cleaning, sun-drying, and impurity removal of all seeds were completed on August 1. The seed quality and yield were detected.

[56] A specific detection method was as follows: [S7] Harvested Cuimei No. 1 test group and control group were divided into three groups, respectively. Each group contained 100 seeds, which were sown in 100-hole or 50-hole plug trays and managed according to the conventional seedling raising method. Germination of each group was recorded after 10 days, and germination percentage was calculated. The calculation formula was as follows: germination percentage % = number of germinated seeds/100.

[58] Germination potential: The number of germinated seeds of each group was recorded at 5 days after sowing, during which the germination potential was the percentage of the number of germinated seeds to the number of all seeds. The calculation formula was as follows: germination potential % = number of germinated seeds at 5 days/100. [S9] Detection results are shown in Tables 5 and 6.

[60] Table 5 The comparison of the quality of hybrid seeds of Cuimei No. 1 Test Thousand-grain Germination Germination pm ee em

28.5 94% 97% Tl

A

31.4 95% 98% T3

EE

[61] Table 6 The comparison of the yield of hybrid seeds of Cuimei No. 1 Test Yield per (Average yield [Average income increase Plot 56 T1 Test group (T) = T2

PE 63 T3 oi MPP CK1 40 45 group (CK)

[62] According to the detection, the seed plumpness was high, the thousand-grain weight reached 30 g, and the seed yield per mr reached 62 kg/mu. According to according to conventional seed production operations, the thousand-grain weight of the cultivar was 28 g, and the yield was 40-50 kg; according to this production technology, the seed quality and yield were increased significantly, the yield per 7: was more than 17 kg, and the yield was increased by more than 37.8%; based on the seed production cost of RMB 400 yuan/kg, the income of seed production was increased by more than 6,800 yuan/mu.

[63] As can be seen from the foregoing examples, the hybrid seed production method provided by the present disclosure may improve the seed quality and yield, the benefits to farmers, and the germination percentage and germination potential of commercial seeds.

[64] The above descriptions are merely preferred implementations of the present disclosure. It should be noted that a person of ordinary skill in the art may further make several improvements and modifications without departing from the principle of the present disclosure, but such improvements and modifications should be deemed as falling within the protection scope of the present disclosure.

Claims

- 14 - Conclusions l. Hybrid seed production method based on subgynoecial cucumber as a female parent, the method comprising the following steps: step 1, the, 4-6 days after sowing seeds from a male parent, sowing the seeds from a female parent, wherein the seeds of the male and female parents have a quantitative ratio of 1:(4 — 6); step 2, performing a first male flower inducing treatment with silver nitrate solution on a seedling stage with one leaf and one bud of the male parent, and after 3-5 days, performing a second male flower inducing treatment with silver nitrate solution; step 3, picking a male flower that has bloomed on the day, applying a part where petals of the male flower have been removed on the stigmas of a female flower, and performing pollination by closing the petals of the female flower flower; and step 4, pollinating and preserving fruits of the 12th leaf of a plant, sequentially pollinating and preserving 2 — 4 fruits, removing all female flowers at buds 5 — 7 above a last fruit bud that sequentially preserve is after pollination, pollinating and preserving a last fruit in blooming female flowers at buds 6 — 8 above the last fruit bud successively preserved after pollination, and removing all unpollinated female flowers.

The hybrid seed production method according to claim 1, wherein the pollination in step 3 is carried out from 8:00 to 12:00 in the morning on a nice day, and the pollination is carried out at a temperature of > 20°C.

The hybrid seed production method according to claim 1 or 2, wherein each male flower in step 3 pollinates a female flower.

A hybrid seed production method according to claim 3, wherein the closing of the petals of the female flower in step 3 is achieved by wrapping and clamping the petals of the female flower with graft clips.

-15 -

The hybrid seed production method according to claim 1, wherein sowing time is from mid-February to mid-April when the method is applied in the Huang-Huai-Hai region, China.

The hybrid seed production method of claim 1, wherein the silver nitrate solution in step 2 has a concentration of 0.25 - 0.35 g/kg.

The hybrid seed production method of claim 1, wherein farm management is performed during the hybrid seed production.

The hybrid seed production method of claim 7, wherein the farm management is applying a base fertilizer before planting a field, disinfecting the soil, managing water and fertilizer at the seedling stage, applying nitrogen and potassium fertilizers after pollination and swelling of fruit, separation of fields and control of pests and diseases.

The hybrid seed production method of claim 8, wherein the pests and diseases comprise fusarium wilt, downy mildew, thrips damage, and aphid damage.

The hybrid seed production method of claim 1, wherein topping is not performed after the pollination in step 3.