Method for grafting and cultivating three-head seedlings on tomato cotyledons

Abstract

The invention discloses a method for grafting and cultivating three-head seedlings on tomato cotyledons. The main leaf part above the tomato scion cotyledon is used for grafting with the rootstock, so that the survival rate is high, and the healing capacity is high; the seeds before sowing are treated by a seed treatment agent, so that tomato damping-off and tomato root rot can be prevented; the healing agent is used at the grafting interface, so that the survival rate of the grafted seedlings is improved, the cultivation survival of the three-head seedlings grafted above the tomato cotyledons is facilitated, and the method has the advantages of saving seeds, reducing labor force, being convenient to manage and the like.

Description

Technical Field

[0001] The invention relates to the technical field of tomato seedling cultivation, and in particular to a method for cultivating three-headed seedlings by grafting on tomato cotyledons. Background Art

[0002] In facility agriculture, tomatoes are a kind of fruit and vegetable with high economic value, but the most common drawback of facility agriculture is the continuous cropping caused by repeated cropping, which will seriously damage the yield and quality of tomatoes. Tomato grafting cultivation can effectively improve the ability of plants to resist abiotic and biotic adversities, enhance water and fertilizer absorption, promote plant growth and development, reduce the incidence and disease index of soil-borne diseases of tomato crops, and increase fruit yield and quality.

[0003] There are two main methods for tomato grafting seedlings: one is to cultivate two-headed seedlings, that is, directly use the cotyledon scion for grafting, remove the lower cotyledon after the seedlings are healed and leave the head, and keep the upper true leaves to provide nutrients for the seedling head, but this method is easy to cause the seedlings to tilt; the other is to use the cotyledon of the scion for grafting, remove the upper true leaves, and directly sprout new branches from the axils of the two cotyledons of the scion, but this method can only leave two heads, reducing the yield after planting. Compared with the method of directly using the cotyledon scion for grafting, the survival rate of the grafted three-headed seedlings using the true leaves above the cotyledons of the tomato scion and the rootstock for grafting is high, and the healing ability and later growth and development are not significantly different from the two grafted seedlings with cotyledon grafting and cotyledon grafting with the head left. The cultivation of three-headed seedlings grafted above the cotyledons of tomato has the advantages of saving seeds, reducing labor, and facilitating management.

[0004] CN114303668A discloses a tomato grafting method in a plant factory, which uses eggplant as a rootstock and tomato as a scion for grafting to obtain a tomato plant with higher stability. However, this method uses large seedlings with a seedling age of 22-24 days to graft, and the degree of lignification of the stems of the seedlings is high, which makes it more difficult for the rootstock and scion to heal, and affects the survival rate of the seedlings.

[0005] CN117178762A discloses a method for grafting multiple plants of one tomato scion, which divides the same scion seedling into three sections, namely, firstly, the cotyledon part is cut off from bottom to top and grafted onto the first batch of sowing stock seedlings; then, 1 to 2 true leaves are cut off and grafted onto the second batch of sowing stock; finally, the remaining scion with the growth point on the top is grafted onto the third batch of sowing stock, thereby improving the utilization rate of the scion seedlings. However, this method easily causes the seedlings to be tilted and the survival rate is low. Summary of the invention

[0006] In view of the above-mentioned defects of the prior art, the present invention provides a method for cultivating three-headed seedlings by grafting on tomato cotyledons. The survival rate, healing ability, and later growth and development of the tomato seedlings grafted by the method provided by the present invention are not significantly different from those of the two types of grafted seedlings grafted with cotyledons and grafted with cotyledons and heads retained. The cultivation of three-headed seedlings grafted above the cotyledons of tomato has the advantages of saving seeds, reducing labor, and facilitating management.

[0007] To achieve the above object, the present invention provides a method for cultivating three-headed seedlings by grafting on tomato cotyledons, comprising the following steps:

[0008] S1. Cultivating rootstock seedlings and tomato scion seedlings: selecting tomato scion seeds and rootstock seeds required for grafting, sowing, dividing and curing them to obtain grafted seedlings for standby use, and sowing the rootstock 36-48 hours after sowing the scion;

[0009] S2, grafting: The stock and scion stems are 1.4-1.8mm thick, and the stock is beveled 1-1.5cm below the cotyledons at an angle of 45-60°. A grafting clip is placed. At the same time, a bevel is made 4-6mm above the cotyledons of the scion at an angle of 45-60°. The scion is placed inside the grafting clip so that the beveled surfaces of the stock and scion fit together;

[0010] S3. Healing and maintenance:

[0011] The daytime temperature of grafted seedlings for 1-3 days is 20-24℃, the humidity is 93-95%, the nighttime temperature is 19-21℃, and the humidity remains unchanged. According to the number of days after grafting and the status of seedlings, ventilation is carried out for 10-30 minutes at 7:00 am and 17:00 pm when the light intensity is less than 200w, and supplementary light is used for 4-7h. The daytime temperature of seedlings grafted for 4-6 days is 20-24℃, the humidity is 85-90%, the nighttime temperature is 17-19℃, and the humidity remains unchanged. Ventilation is carried out for 30-60 minutes at 7:00 am and 17:00 pm when the light intensity is less than 200w, and supplementary light is used for 6-12h. After the 6th day, the grafted seedlings can be taken out of the healing room for seedling hardening.

[0012] Or, step S1 is to cultivate rootstock seedlings and tomato scion seedlings: tomato scion seeds and rootstock seeds required for grafting are selected respectively, and the seeds are treated according to a mass ratio of 1:5-10 between seeds and seed treatment agent; then the treated seeds are sown, separated and maintained to obtain grafted seedlings for standby use, and the rootstock is sown 36-48 hours after the scion is sown;

[0013] Step S2 grafting: the stock and scion stems are 1.4-1.8 mm in diameter, and are beveled 1-1.5 cm below the stock cotyledons at an angle of 45-60°, and a grafting clamp is placed; at the same time, beveled 4-6 mm above the scion cotyledons at an angle of 45-60°, and the scion is placed inside the grafting clamp so that the beveled surfaces of the stock and scion fit together, and a healing agent is used to treat the interface.

[0014] Preferably, the seed cultivation conditions of step S1 are as follows: during the germination period of scion sowing, the germination room has a 24h average temperature of 24°C and an average humidity of 70-90%, and the scion seeds are transferred to a greenhouse for maintenance after they turn white; the daytime average temperature is maintained at 22-24°C, the nighttime average temperature is 18-19°C, and the humidity is 60-80% from 3d to 11d after sowing; the daytime average temperature is maintained at 22-24°C from 12d to 14d after sowing, the nighttime average temperature is increased to 19-20°C, and the humidity remains unchanged.

[0015] As a further explanation of the present invention, the inventors choose to graft when the thickness of the scion seedling stem reaches 1.4-1.8mm. At this time, the physiological seedling age of tomatoes is 2 leaves and 1 heart to 3 leaves and 1 heart. The true leaf part above the cotyledons of the tomato scion is used for grafting with the rootstock. The degree of lignification of the seedling stem is low, and the scion and the rootstock heal quickly. Grafting at this stage is easy to operate and has a high survival rate. It is also not easy to produce adventitious roots that cause false life and affect the quality of the seedlings. The problem of tillering is fundamentally solved, the tillering process of tomato grafting seedlings is reduced, labor costs are saved, and the probability of disease occurrence is reduced. Compared with grafting with cotyledons, the seedlings are more robust and the risk of seedling disease is reduced.

[0016] Preferably, the rootstock seeds in step S1 are selected from one of rootstock MAXIFORT and rootstock 150.

[0017] Preferably, the scion seeds in step S1 are selected from one of SAOPOLO HF1, Crown 16, Jin Xiaoling, Lifei, Honghui 69, Lianhong, Yanfei, Crown No. 3, and Black Pearl No. 2.

[0018] Preferably, the preparation method of the seed treatment agent in step S1 comprises the following steps, calculated by weight:

[0019] a. Inoculate the bacteria at an inoculum of 2-3wt% in a culture medium consisting of 2-5wt% glucose, 5-10wt% agar, 2-5wt% peptone, 2-5wt% beef extract, and the remainder water; culture at 28-34°C, 120-150rpm, and aerobic conditions for 40-48h to obtain a bacterial culture solution;

[0020] b. The bacterial solution of step a is inoculated into a potato dextrose agar medium at an inoculum size of 2-5 wt %, and aerobically fermented at 28-34° C. for 25-30 h. The pH of the fermented solution is then adjusted to 6-7 with a 2-3 mol / L sodium bicarbonate aqueous solution. The fermented solution is filtered and vacuum concentrated to 30-50% of the original volume to obtain a bacterial fermented solution.

[0021] c. Dry 100-200 parts of astragalus, crush them, and pass them through an 80-120 mesh sieve for later use. Soak them in 60-80wt% ethanol at a mass ratio of 1:5-10 for astragalus powder and 60-80wt% ethanol, stir them so that the solvent completely immerses the astragalus powder, let them stand at room temperature and away from light for 16-48 hours, perform ultrasonic-assisted extraction at 40-50°C and 70-100Hz for 30-60 minutes, filter them, collect the filtrate, treat the residue again with the same method, repeat the extraction 2-4 times, and combine the filtrate; make the filtrate into an extract to obtain an astragalus extract;

[0022] d. Mix 10-30 parts of the bacterial fermentation liquid of step b, 4-8 parts of pectin and 1-5 parts of sodium carboxymethyl cellulose, then add 1-5 parts of the astragalus extract obtained in step c and 1-3 parts of a dispersant, stir and mix evenly to obtain a seed treatment agent.

[0023] Preferably, the bacteria in step a is selected from one of Bacillus polymyxa, Bacillus subtilis and Bacillus megaterium.

[0024] Preferably, the dispersant in step d is at least one of sodium lignin sulfonate and sodium dodecylbenzene sulfonate.

[0025] The most common diseases of tomato seedlings are root rot and damping-off. Damping-off mainly occurs in the early stage of seedling cultivation, especially when the cotyledons of the seedlings are exhausted and the new roots are not solid. Its symptoms include water-soaked spots at the base of the stems, which quickly turn yellow-brown, and the diseased parts are constricted and linear. When the humidity is high, large areas of seedlings will wilt suddenly, and white flocculent hyphae will grow on the surface of the diseased seedling residues and the nearby bed surface. In the early stage of root rot, individual lateral roots and fibrous roots are infected, and gradually spread to the taproot. After the taproot is infected, the early plants do not show symptoms, but as the degree of root rot increases, the aboveground part is in short supply of nutrients, and the new leaves turn yellow first. When the light is strong around noon and the evaporation is large, the upper leaves of the plant wilt. When the disease is serious, the wilting condition cannot be restored at night, and the leaves of the whole plant turn yellow and wither.

[0026] In view of the above situation, the inventors found that the tomato seeds were treated with seed treatment agents before sowing. The treated seeds can form a protective layer around the plant rhizosphere when the seedlings grow, which is beneficial for the seedlings to be protected from pathogens. The polymyxa bacillus added to the seed treatment agent can produce antibacterial substances that can inhibit and kill pathogens. The astragalus extract contains flavonol glycosides, which have a good inhibitory effect on pathogens. At the same time, the treatment agent itself can also provide nutrition for crops, effectively control soil-borne diseases in the seedling stage, promote the root growth of seedlings, improve the quality of seedlings, promote growth and development, and achieve increased production.

[0027] Preferably, the healing agent of step S2 is prepared by the following method: by weight, 0.001-0.01 parts of 3-indoleacetic acid, 0.001-0.01 parts of superoxide dismutase, 0.001-0.01 parts of 6-benzylaminopurine, 0.001-0.1 parts of abscisic acid and 1-5 parts of chitosan are added to 100-500 parts of 0.7-0.8wt% acetic acid aqueous solution, mixed and stirred to obtain a mixed solution A; 1-5 parts of sodium hyaluronate, 0.1-0.5 parts of calcium lactate and 0.1-0.5 parts of sodium nitrophenolate are added to 100-500 parts of water, mixed and stirred to obtain a mixed solution B; the mixed solution A and the mixed solution B are mixed in a mass ratio of 1-5:1-5, stirred at 800-1000 rpm for reaction at room temperature for 0.5-1.5h, centrifuged at 1000-3000 rpm for 10-20min, and the supernatant is discarded to obtain a healing agent.

[0028] As a further illustration of the present invention, the inventors found that the use of a healing agent at the grafting interface is conducive to the healing of the wound between the tomato scion and the stock. The reason for the analysis may be that chitosan and sodium hyaluronate can work together to form a hydrogel protective film to prevent infection by foreign substances; the addition of 3-indoleacetic acid, superoxide dismutase, 6-benzylaminopurine, abscisic acid, calcium lactate, and sodium nitrophenolate can promote cell division, promote lignification, remove excess active oxygen at the interface, and avoid oxidative damage, effectively promote the healing of the grafting interface, and improve the survival rate of the grafted seedlings.

[0029] The beneficial effects of the present invention are as follows:

[0030] Compared with the prior art, the method for cultivating three-headed seedlings by grafting on tomato cotyledons provided by the present invention can make the grafted seedlings less likely to produce adventitious roots, causing false liveness and other phenomena that affect the quality of seedlings, fundamentally solve the problem of tillering, reduce the tillering removal link of tomato grafted seedlings, save labor costs, reduce the probability of disease occurrence, and is more robust than cotyledon grafted seedlings, reducing the risk of seedling diseases. In the process of grafting and cultivation, by using seed treatment agents for treatment, tomato seedling root rot and damping-off can be prevented, and the use of healing agents can improve the survival rate of tomato grafting. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attached Figure 1 This is a schematic diagram of the grafting process;

[0032] Attached Figure 2 To provide healing maintenance for the grafted seedlings above the cotyledons;

[0033] Attached Figure 3 Leave the head for grafting seedlings above the cotyledons;

[0034] Attached Figure 4 Transplant the seedlings grafted above the cotyledons;

[0035] Attached Figure 5 Graft the seedlings above the cotyledons to grow into large seedlings. DETAILED DESCRIPTION

[0036] The parameters and sources of some raw materials in the embodiments of the present invention are as follows:

[0037] Paenibacillus polymyxa, CICC 10494, a commercial product, was purchased from China Industrial Microbiological Culture Collection Management Center;

[0038] Bacillus subtilis, CICC 10732, a commercial product, was purchased from China Industrial Microbiological Culture Collection Center;

[0039] Bacillus megaterium, CICC 20167, commercially available product, purchased from China Industrial Microbiological Culture Collection Center;

[0040] Pectin, product number: P750269, yellow powder, from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0041] Sodium carboxymethyl cellulose, product number: C6332, viscosity: 1500-3100 mPa.s, from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0042] Sodium lignin sulfonate, product number: S980880, Mw5000-10000, from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0043] 3-Indoleacetic acid, product number: I811602, from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0044] Superoxide dismutase, product number: S6375, was obtained from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0045] 6-Benzylaminopurine, product number: B802626, from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0046] Abscisic acid, product number: A915682, was obtained from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0047] Chitosan, product number: C804729, medium viscosity, 200-400 mPa.s, from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0048] Sodium hyaluronate, product number: H832247, from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0049] Calcium lactate, product number: 1067238, from Shanghai Haohong Biopharmaceutical Technology Co., Ltd.;

[0050] Sodium nitrophenolate, CAS: 123-30-8.

[0051] Example 1

[0052] A method for cultivating three-headed seedlings by grafting on tomato cotyledons comprises the following steps:

[0053] S1. Cultivating rootstock seedlings and tomato scion seedlings: selecting SAOPOLO HF1 tomato scion seeds and MAXIFORT rootstock seeds required for grafting, sowing, dividing and curing them to obtain grafted seedlings for standby use, and sowing the rootstock 48 hours after sowing the scion; wherein, the cultivation conditions are as follows: during the scion sowing and germination period, the 24-hour average temperature in the germination room is 24°C, and the average humidity is 80%, and the scion seeds are transferred to the greenhouse for curing after turning white; the daytime average temperature is maintained at 22-24°C from 3d to 11d after sowing, the nighttime average temperature is 19°C, and the humidity is 70%; the daytime average temperature is maintained at 22-24°C from 12d to 14d after sowing, the nighttime average temperature is increased to 20°C, and the humidity remains unchanged.

[0054] S2, grafting: The stock and scion stems are 1.6 mm thick, and the stock is beveled 1.5 cm below the cotyledons at a bevel angle of 45°. A grafting clip is placed. At the same time, a bevel is made 5 mm above the cotyledons of the scion at a bevel angle of 45°. The scion is placed inside the grafting clip so that the beveled surfaces of the stock and scion fit together;

[0055] S3. Healing and maintenance: The daytime temperature for grafted seedlings 1-3 days is 20-24℃, and the humidity is 94%. The nighttime temperature is 19-21℃, and the humidity remains unchanged. According to the number of days after grafting and the status of the seedlings, ventilation is carried out for 15 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 4 hours; the daytime temperature for seedlings grafted 4-6 days is 20-24℃, and the humidity is 90%. The nighttime temperature is 17-19℃, and the humidity remains unchanged. Ventilation is carried out for 60 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 12 hours; after the 6th day, the grafted seedlings can be taken out of the healing room for seedling hardening.

[0056] Example 2

[0057] A method for cultivating three-headed seedlings by grafting on tomato cotyledons comprises the following steps:

[0058] S1. Cultivating rootstock seedlings and tomato scion seedlings: selecting SAOPOLO HF1 tomato scion seeds and MAXIFORT rootstock seeds required for grafting, treating them according to a mass ratio of 1:7 between seeds and seed treatment agent, then sowing, dividing and curing to obtain grafted seedlings for standby use, and sowing the rootstock 48 hours after sowing the scion; wherein, the cultivation conditions are as follows: during the scion sowing and germination period, the 24-hour average temperature in the germination room is 24°C, the average humidity is 80%, and the scion seeds are transferred to the greenhouse for curing after turning white; the daytime average temperature is maintained at 22-24°C from 3d to 11d after sowing, the nighttime average temperature is 19°C, and the humidity is 70%; the daytime average temperature is maintained at 22-24°C from 12d to 14d after sowing, the nighttime average temperature is increased to 20°C, and the humidity remains unchanged;

[0059] S2, grafting: The stock and scion stems are 1.6mm thick, and the stock is beveled 1.5cm below the cotyledons at a bevel angle of 45°. A grafting clip is placed. At the same time, a bevel is made 5mm above the cotyledons of the scion at a bevel angle of 45°. The scion is placed inside the grafting clip so that the beveled surfaces of the stock and scion fit together, and the interface is treated with a healing agent;

[0060] S3. Healing and maintenance: The daytime temperature for grafted seedlings 1-3 days is 20-24℃, and the humidity is 94%. The nighttime temperature is 19-21℃, and the humidity remains unchanged. According to the number of days after grafting and the status of the seedlings, ventilation is carried out for 15 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 4 hours; the daytime temperature for seedlings grafted 4-6 days is 20-24℃, and the humidity is 90%. The nighttime temperature is 17-19℃, and the humidity remains unchanged. Ventilation is carried out for 60 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 12 hours; after the 6th day, the grafted seedlings can be taken out of the healing room for seedling hardening.

[0061] The preparation method of the seed treatment agent in step S1 comprises the following steps:

[0062] a. Inoculate Paenibacillus polymyxa at an inoculum rate of 2 wt % into a culture medium consisting of 3 wt % glucose, 7 wt % agar, 3 wt % peptone, 3 wt % beef extract, and the remainder water; culture at 30° C., 130 rpm, and aerobic conditions for 48 h to obtain a bacterial culture solution;

[0063] b. The bacterial solution of step a was inoculated into a potato dextrose agar medium at an inoculum rate of 3 wt %, and aerobically fermented at 30° C. for 28 h. The pH of the fermentation solution was then adjusted to 7 with a 2 mol / L sodium bicarbonate aqueous solution. The fermentation solution was filtered and concentrated in vacuo to 30% of the original volume to obtain a bacterial fermentation solution.

[0064] c. Dry and crush 100 g of astragalus, pass it through a 100-mesh sieve, soak it with 500 g of 70% ethanol, stir it to make the solvent completely immerse the astragalus powder, let it stand for 24 hours, perform ultrasonic-assisted extraction at 45°C and 80 Hz for 45 minutes, filter it to obtain a filtrate, and treat the residue again in the same way. Repeat the extraction 3 times and combine the filtrates; the filtrate is in the form of an extract to obtain an astragalus extract;

[0065] d. Mix 20 g of the bacterial fermentation liquid of step b, 6 g of pectin and 3 g of sodium carboxymethyl cellulose, add 3 g of astragalus extract and 2 g of sodium lignin sulfonate, stir and mix evenly to obtain a seed treatment agent.

[0066] The preparation method of the healing agent in step S2 comprises the following steps:

[0067] 0.005 g of 3-indoleacetic acid, 0.005 g of superoxide dismutase, 0.005 g of 6-benzylaminopurine, 0.005 g of abscisic acid and 2 g of chitosan are added to 200 g of 0.75 wt % acetic acid aqueous solution, stirred and mixed to obtain a mixed solution A; 2 g of sodium hyaluronate, 0.3 g of calcium lactate and 0.2 g of sodium nitrophenolate are added to 200 g of water, stirred and mixed to obtain a mixed solution B; the mixed solution A and the mixed solution B are mixed at a mass ratio of 1:1, stirred and reacted at 900 rpm for 1 hour at room temperature, centrifuged at 2000 rpm for 15 minutes, and the supernatant is discarded to obtain a healing agent.

[0068] Example 3

[0069] A method for cultivating three-headed seedlings by grafting on tomato cotyledons, which is different from Example 2 in that the preparation method of the seed treatment agent in step S1 comprises the following steps:

[0070] a. Inoculate Bacillus subtilis at an inoculum rate of 2 wt % in a culture medium consisting of 3 wt % glucose, 7 wt % agar, 3 wt % peptone, 3 wt % beef extract, and the remainder being water; culture the culture at 30° C., 130 rpm, and aerobic conditions for 48 h to obtain a bacterial culture solution;

[0071] b. The bacterial solution of step a was inoculated into a potato dextrose agar medium at an inoculum rate of 3 wt %, and aerobically fermented at 30° C. for 28 h. The pH of the fermentation solution was then adjusted to 7 with a 2 mol / L sodium bicarbonate aqueous solution. The fermentation solution was filtered and concentrated in vacuo to 30% of the original volume to obtain a bacterial fermentation solution.

[0072] c. Dry and crush 100 g of astragalus, pass it through a 100-mesh sieve, soak it with 500 g of 70% ethanol, stir it to make the solvent completely immerse the astragalus powder, let it stand for 24 hours, perform ultrasonic-assisted extraction at 45°C and 80 Hz for 45 minutes, filter it to obtain a filtrate, and treat the residue again in the same way. Repeat the extraction 3 times and combine the filtrates; the filtrate is in the form of an extract to obtain an astragalus extract;

[0073] d. Mix 20 g of the bacterial fermentation liquid of step b, 6 g of pectin and 3 g of sodium carboxymethyl cellulose, add 3 g of astragalus extract and 2 g of sodium lignin sulfonate, stir and mix evenly to obtain a seed treatment agent.

[0074] Example 4

[0075] A method for cultivating three-headed seedlings by grafting on tomato cotyledons, which is different from Example 2 in that the preparation method of the seed treatment agent in step S1 comprises the following steps:

[0076] a. Inoculate Bacillus megaterium at an inoculum rate of 2 wt % in a culture medium consisting of 3 wt % glucose, 7 wt % agar, 3 wt % peptone, 3 wt % beef extract, and the remainder being water; culture at 30° C., 130 rpm, and aerobic conditions for 48 h to obtain a bacterial culture solution;

[0077] b. The bacterial solution of step a was inoculated into a potato dextrose agar medium at an inoculum rate of 3 wt %, and aerobically fermented at 30° C. for 28 h. The pH of the fermentation solution was then adjusted to 7 with a 2 mol / L sodium bicarbonate aqueous solution. The fermentation solution was filtered and concentrated in vacuo to 30% of the original volume to obtain a bacterial fermentation solution.

[0078] c. Dry and crush 100 g of astragalus, sieve through a 100-mesh sieve for later use, soak with 500 g of 70% ethanol, stir until the solvent completely submerges the astragalus powder, leave it at rest for 24 h, perform ultrasonic-assisted extraction at 45 ° C and 80 Hz for 45 min, filter to obtain a filtrate, and treat the residue again in the same way. Repeat the extraction 3 times and combine the filtrates; the filtrate is in the form of an extract to obtain an astragalus extract;

[0079] d. Mix 20 g of the bacterial fermentation liquid of step b, 6 g of pectin and 3 g of sodium carboxymethyl cellulose, add 3 g of astragalus extract and 2 g of sodium lignin sulfonate, stir and mix evenly to obtain a seed treatment agent.

[0080] Example 5

[0081] A method for cultivating three-headed seedlings by grafting on tomato cotyledons comprises the following steps:

[0082] S1. Cultivating rootstock seedlings and tomato scion seedlings: select SAOPOLO HF1 tomato scion seeds and MAXIFORT rootstock seeds required for grafting, treat them according to the mass ratio of seeds to seed treatment agent of 1:7, sow them, divide them into seedlings, and maintain them to obtain grafted seedlings for standby use, and sow the rootstock 48 hours after sowing the scion; wherein, the cultivation conditions are: during the scion sowing and germination period, the 24h average temperature in the germination room is 24°C, the average humidity is 80%, and the grafted seeds are transferred to the greenhouse for maintenance after they turn white; the daytime average temperature is maintained at 22-24°C from 3d to 11d after sowing, the nighttime average temperature is 19°C, and the humidity is 70%; the daytime average temperature is maintained at 22-24°C from 12d to 14d after sowing, the nighttime average temperature is increased to 20°C, and the humidity remains unchanged;

[0083] S2, grafting: The stock and scion stems are 1.6 mm thick, and the stock is beveled 1.5 cm below the cotyledons at a bevel angle of 45°. A grafting clip is placed. At the same time, a bevel is made 5 mm above the cotyledons of the scion at a bevel angle of 45°. The scion is placed inside the grafting clip so that the beveled surfaces of the stock and scion fit together;

[0084] S3. Healing and maintenance: The daytime temperature for grafted seedlings 1-3 days is 20-24℃, and the humidity is 94%. The nighttime temperature is 19-21℃, and the humidity remains unchanged. According to the number of days after grafting and the status of the seedlings, ventilation is carried out for 15 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 4 hours; the daytime temperature for seedlings grafted 4-6 days is 20-24℃, and the humidity is 90%. The nighttime temperature is 17-19℃, and the humidity remains unchanged. Ventilation is carried out for 60 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 12 hours; after the 6th day, the grafted seedlings can be taken out of the healing room for seedling hardening.

[0085] The preparation method of the seed treatment agent in step S1 is consistent with that in Example 2.

[0086] Example 6

[0087] A method for cultivating three-headed seedlings by grafting on tomato cotyledons comprises the following steps:

[0088] S1. Cultivate rootstock seedlings and tomato scion seedlings: select SAOPOLO HF1 tomato scion seeds and MAXIFORT rootstock seeds required for grafting, sow, separate and maintain them to obtain grafted seedlings for standby use, and sow the rootstock 48 hours after sowing the scion; wherein, the cultivation conditions are as follows: during the scion sowing and germination period, the 24-hour average temperature in the germination room is 24°C, the average humidity is 80%, and the grafted seeds are transferred to the greenhouse for maintenance after they turn white; the daytime average temperature is maintained at 22-24°C from the 3rd to the 11th day after sowing, the nighttime average temperature is 19°C, and the humidity is 70%; the daytime average temperature is maintained at 22-24°C from the 12th to the 14th day after sowing, the nighttime average temperature is increased to 20°C, and the humidity remains unchanged;

[0089] S2, grafting: The stock and scion stems are 1.6mm thick, and the stock is beveled 1.5cm below the cotyledons at a bevel angle of 45°. A grafting clip is placed. At the same time, a bevel is made 5mm above the cotyledons of the scion at a bevel angle of 45°. The scion is placed inside the grafting clip so that the beveled surfaces of the stock and scion fit together, and the interface is treated with a healing agent;

[0090] S3. Healing and maintenance: The daytime temperature for grafted seedlings 1-3 days is 20-24℃, and the humidity is 94%. The nighttime temperature is 19-21℃, and the humidity remains unchanged. According to the number of days after grafting and the status of the seedlings, ventilation is carried out for 15 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 4 hours; the daytime temperature for seedlings grafted 4-6 days is 20-24℃, and the humidity is 90%. The nighttime temperature is 17-19℃, and the humidity remains unchanged. Ventilation is carried out for 60 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 12 hours; after the 6th day, the grafted seedlings can be taken out of the healing room for seedling hardening.

[0091] The preparation method of the healing agent in step S2 is consistent with that in Example 2.

[0092] Comparative Example 1

[0093] A method for cultivating three-headed seedlings by grafting on tomato cotyledons comprises the following steps:

[0094] S1. Cultivate rootstock seedlings and tomato scion seedlings: select SAOPOLO HF1 tomato scion seeds and MAXIFORT rootstock seeds required for grafting, sow, separate and maintain them to obtain grafted seedlings for standby use, and sow the rootstock 48 hours after the scion is sown; wherein, the cultivation conditions are: during the scion sowing and germination period, the 24-hour average temperature in the germination room is 22-24°C, the average humidity is 80%, and the scion seeds are transferred to the greenhouse for maintenance after they turn white; the daytime average temperature is maintained at 22-24°C from the 3rd to the 11th day after sowing, the nighttime average temperature is 19°C, and the humidity is 70%; the daytime average temperature is maintained at 22-24°C from the 12th to the 14th day after sowing, the nighttime average temperature is increased to 20°C, and the humidity remains unchanged;

[0095] S2, grafting: The stock and scion stems are 1.6 mm thick, and the stock is beveled 1.5 cm below the cotyledons at a bevel angle of 45°. A grafting clip is placed. At the same time, a bevel is made 5 mm below the cotyledons of the scion at a bevel angle of 45°. The scion is placed inside the grafting clip so that the beveled surfaces of the stock and scion fit together;

[0096] S3. Healing and maintenance: The daytime temperature for grafted seedlings 1-3 days is 20-24℃, and the humidity is 94%. The nighttime temperature is 19-21℃, and the humidity remains unchanged. According to the number of days after grafting and the status of the seedlings, ventilation is carried out for 15 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 4 hours; the daytime temperature for seedlings grafted 4-6 days is 20-24℃, and the humidity is 90%. The nighttime temperature is 17-19℃, and the humidity remains unchanged. Ventilation is carried out for 60 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary lighting is used for 12 hours; after the 6th day, the grafted seedlings can be taken out of the healing room for seedling hardening.

[0097] Test Example 1

[0098] Survival rate test

[0099] The cultivation methods of Examples 1-6 and Comparative Example 1 were used, and three trays were cultivated for each cultivation method, with 720 plants in each tray. After the grafting was cured and maintained, the survival rate of the grafted tomato seedlings was tested. The test results are shown in Table 1.

[0100] Table 1 Survival rate

[0101]

[0102] By comparing Example 1 with Comparative Example 1, it can be found that the survival rate of Example 1 is higher than that of Comparative Example 1. The possible reason is that the grafting of Example 1 is the true leaves above the cotyledons, the required nutrients are less than the grafting method with cotyledons, the healing effect between the rootstock is better, and the survival rate is higher.

[0103] By comparing Examples 1-6, it can be found that Example 2 has the highest survival rate. The possible reason is that Example 2 tried a healing agent during the healing process. The chitosan and sodium hyaluronate in the healing agent can work together to form a hydrogel protective film to prevent foreign substances from infecting; the addition of 3-indoleacetic acid, superoxide dismutase, 6-benzylaminopurine, abscisic acid, calcium lactate, and sodium nitrophenol in the healing agent can promote cell division, promote lignification, remove excessive active oxygen at the interface, avoid oxidative damage, effectively promote the healing of the graft interface, and improve the survival rate of the grafted seedlings.

[0104] Test Example 2

[0105] Seedling head deviation rate

[0106] The cultivation methods of Examples 1-2 and Comparative Example 1 were used for cultivation. Three trays with 720 plants per tray were cultivated using each cultivation method. After the grafts were cured and maintained and the grafting clips were removed, the unsuccessful ones were removed. Three tomato grafting experts comprehensively judged whether the seedlings were head-biased based on the growth of side branches, the symmetry of the growth points and the overall morphology of the plants, and calculated the head-bias rate. The lower the head-bias rate, the better. The head-bias rate calculation formula is as follows:

[0107] Head deviation rate (%) = number of head deviation seedlings ÷ total number of plants tested × 100%

[0108] The test results are shown in Table 2.

[0109] Table 2 Head deviation rate

[0110] Project / No. Example 1 Example 2 Comparative Example 1 Head deviation rate (%) 1.11 0.14 10.56

[0111] By comparing Examples 1-2 with Comparative Example 1, it can be found that Example 2 has the lowest head deviation rate. The possible reason is that Example 2 grafts the true leaves above the cotyledons and uses a healing agent, the healing effect at the grafting interface is good, and there is no need to remove the tillers, so the head deviation rate is low. The scion in Comparative Example 1 is a scion without removing the cotyledons, which is prone to tillering and causes the plant head deviation.

[0112] Test Example 3

[0113] Effectiveness against tomato damping-off and tomato root rot

[0114] The cultivation method of Examples 1-4 was cultivated until the grafting site healed. Each example of the cultivation method of Examples 1-4 cultivated 200 plants, and the cultivated seedlings were divided into two groups, and 100 plants in each group were transplanted into a matrix mixed with tomato damping-off disease and tomato root rot pathogens; a group of untreated and ungrafted SAOPOLO HF1 tomato scion seeds were sown and cultivated under the same conditions as the scion seeds of the above examples as a blank control, and the mortality rate of tomato seedlings was investigated after 21 days. The above experimental operation was repeated three times, and the control effect was calculated. The higher the control effect, the better; the control effect calculation formula is as follows:

[0115] Control effect (%) = (disease index of blank control group - disease index of test group) / disease index of blank control group × 100%

[0116] The test results are shown in Table 3.

[0117] Table 3 Control effect

[0118]

[0119] By comparing Examples 1-4, it can be found that Example 2 has the best control effect. The possible reason is that the seed treatment agent added in Example 2 can form a protective layer around the plant rhizosphere, the added Paenibacillus polymyxa can produce antibacterial substances that can inhibit and kill pathogens, and the Astragalus extract contains flavonol glycosides, which have a good inhibitory effect on pathogens; and the combined effect of Paenibacillus polymyxa and Astragalus extract is better than that of Bacillus subtilis and Bacillus megaterium.

Claims

1. A method for cultivating three-headed seedlings by grafting on tomato cotyledons, characterized in that: The steps include: S1. Cultivating rootstock seedlings and tomato scion seedlings: selecting tomato scion seeds and rootstock seeds required for grafting, sowing, dividing and curing them to obtain grafted seedlings for standby use, and sowing the rootstock 36-48 hours after sowing the scion; S2, grafting: The stock and scion stems are 1.4-1.8mm thick, and the stock is beveled 1-1.5cm below the cotyledons at an angle of 45-60°. A grafting clip is placed. At the same time, a bevel is made 4-6mm above the cotyledons of the scion at an angle of 45-60°. The scion is placed inside the grafting clip so that the beveled surfaces of the stock and scion fit together; S3. Healing maintenance: The daytime temperature of grafted seedlings is 20-24℃, the humidity is 93-95%, and the nighttime temperature is 19-21℃, and the humidity remains unchanged. According to the number of days after grafting and the status of seedlings, ventilation is carried out for 10-30 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary light is used for 4-7h. The daytime temperature of seedlings grafted for 4-6d is 20-24℃, the humidity is 85-90%, and the nighttime temperature is 17-19℃, and the humidity remains unchanged. Ventilation is carried out for 30-60 minutes at 7:00 am and 17:00 pm every day when the light intensity is less than 200w, and supplementary light is used for 6-12h. After the 6th day, the grafted seedlings can be taken out of the healing room for seedling hardening; Or, step S1 is to cultivate rootstock seedlings and tomato scion seedlings: tomato scion seeds and rootstock seeds required for grafting are selected respectively, and the seeds are treated according to a mass ratio of 1:5-10 between seeds and seed treatment agent; then the treated seeds are sown, separated and maintained to obtain grafted seedlings for standby use, and the rootstock is sown 36-48 hours after the scion is sown; Step S2 grafting: the stock and scion stems are 1.4-1.8 mm in diameter, and are beveled 1-1.5 cm below the stock cotyledons at an angle of 45-60°, and a grafting clamp is placed; at the same time, beveled 4-6 mm above the scion cotyledons at an angle of 45-60°, and the scion is placed inside the grafting clamp so that the beveled surfaces of the stock and scion fit together, and a healing agent is used to treat the interface.

2. The method for cultivating three-headed seedlings by grafting on tomato cotyledons as claimed in claim 1, characterized in that: The seed cultivation conditions of step S1 are as follows: during the budding period of sowing the scion, the 24h average temperature in the germination room is 20-28°C, the average humidity is 70-90%, and the scion seeds are transferred to the greenhouse for maintenance after turning white; the daytime average temperature is maintained at 22-24°C, the nighttime average temperature is 18-19°C, and the humidity is 60-80% from the 3rd to 11th day after sowing; the daytime average temperature is maintained at 22-24°C from the 12th to 14th day after sowing, the nighttime average temperature is increased to 19-20°C, and the humidity remains unchanged.

3. The method for cultivating three-headed seedlings by grafting on tomato cotyledons as claimed in claim 1, characterized in that: The rootstock seeds in step S1 are selected from one of the rootstocks MAXIFORT and 150.

4. The method for cultivating three-headed seedlings by grafting on tomato cotyledons as claimed in claim 1, characterized in that: The scion seeds in step S1 are selected from one of SAOPOLO HF1, Crown 16, Jin Xiaoling, Lifei, Honghui 69, Lianhong, Yanfei, Crown No. 3, and Black Pearl No.

2.

5. The method for cultivating three-headed seedlings by grafting on tomato cotyledons as claimed in claim 1, characterized in that: The preparation method of the seed treatment agent in step S1 comprises the following steps, calculated by weight: a. Inoculate the inoculated bacteria in a culture medium consisting of 2-5wt% glucose, 5-10wt% agar, 2-5wt% peptone, 2-5wt% beef extract, and the balance water at an inoculum amount of 2-3wt%; culture at 28-34°C, 120-150rpm, and aerobic conditions for 40-48h to obtain a bacterial culture solution; b. The bacterial solution of step a is inoculated into a potato dextrose agar medium at an inoculum size of 2-5 wt %, and aerobically fermented at 28-34° C. for 25-30 h. The pH of the fermented solution is then adjusted to 6-7 with a 2-3 mol / L sodium bicarbonate aqueous solution. The fermented solution is filtered and vacuum concentrated to 30-50% of the original volume to obtain a bacterial fermented solution. c. Dry 100-200 parts of astragalus, crush them, and pass them through an 80-120 mesh sieve for later use. Soak them in 60-80wt% ethanol at a mass ratio of 1:5-10 for astragalus powder and 60-80wt% ethanol, stir them so that the solvent completely immerses the astragalus powder, let them stand at room temperature and away from light for 16-48 hours, perform ultrasonic-assisted extraction at 40-50°C and 70-100Hz for 30-60 minutes, filter them, collect the filtrate, treat the residue again with the same method, repeat the extraction 2-4 times, and combine the filtrate; make the filtrate into an extract to obtain an astragalus extract; d. Mix 10-30 parts of the bacterial fermentation liquid of step b, 4-8 parts of pectin and 1-5 parts of sodium carboxymethyl cellulose, then add 1-5 parts of the astragalus extract obtained in step c and 1-3 parts of a dispersant, stir and mix evenly to obtain a seed treatment agent.

6. The method for cultivating three-headed seedlings by grafting on tomato cotyledons as claimed in claim 5, characterized in that: The bacteria in step a is selected from one of Bacillus polymyxa, Bacillus subtilis and Bacillus megaterium.

7. The method for cultivating three-headed seedlings by grafting on tomato cotyledons as claimed in claim 5, characterized in that: In the step d, the dispersant is selected from at least one of sodium lignin sulfonate and sodium dodecylbenzene sulfonate.

8. The method for cultivating three-headed seedlings by grafting on tomato cotyledons as claimed in claim 1, characterized in that: The preparation method of the healing agent in step S2 comprises the following steps, calculated by weight: 0.001-0.01 parts of 3-indoleacetic acid, 0.001-0.01 parts of superoxide dismutase, 0.001-0.01 parts of 6-benzylaminopurine, 0.001-0.1 parts of abscisic acid and 1-5 parts of chitosan are added to 100-500 parts of 0.7-0.8wt% acetic acid aqueous solution, mixed and stirred to obtain a mixed solution A; 1-5 parts of sodium hyaluronate, 0.1-0.5 parts of calcium lactate and 0.1-0.5 parts of sodium nitrophenolate are added to 100-500 parts of water, mixed and stirred to obtain a mixed solution B; the mixed solution A and the mixed solution B are mixed in a mass ratio of 1-5:1-5, mixed and stirred at room temperature and 800-1000rpm for 0.5-1.5h; then centrifuged at 1000-3000rpm for 10-20min, and the supernatant is discarded to obtain a healing agent.

9. A method for cultivating three-headed seedlings by grafting on tomato cotyledons, characterized in that: Cultivated by the method according to any one of claims 1 to 8.

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