A method for cultivating cabbage seedlings suitable for transplanting by an automatic seedling transplanting machine

Abstract

The application discloses a cabbage seedling raising method suitable for planting by an automatic seedling taking and transplanting machine and belongs to the technical field of cabbage seedling raising. The seedling raising method comprises the following steps: (1) hole disc and disinfection; (2) sowing; (3) seedling emergence period; (4) seedling raising period; (5) high seedling treatment; (6) growth period; and (7) seedling hardening period. The seedling raising method can solve the problems that cabbage seedlings are not uniform in emergence, the plant height and stem thickness are unreasonable, the squatting seedling time is long and it is difficult to cultivate the cabbage seedlings suitable for the automatic seedling taking and transplanting machine.

Description

Technical Field

[0001] This invention relates to the field of cabbage seedling technology, and in particular to a method for raising cabbage seedlings suitable for planting with an automatic seedling transplanter. Background Technology

[0002] Cabbage is rich in nutrients and easy to cultivate on a large scale in open fields. It is one of the important vegetables supplied and exported by my country, with an annual planting area of ​​approximately 900,000 hectares. With changes in planting structure and consumers' recognition of its nutritional value, the cultivation area continues to expand. The scale of planting is shifting from scattered transplanting by individual farmers to intensive, specialized, and large-scale production, especially with the rapid development of large-scale production. This has led to an increasingly strong demand for efficient and simplified cultivation techniques. Transplanting is the most important step in cabbage production, accounting for about 30% of the total labor. Although there is a lot of transplanting machinery in production, its application rate is less than 20%. One of the main reasons is that the seedlings produced by existing seedling raising techniques do not meet the requirements for automatic seedling removal and transplanting, resulting in low success rates and high seedling damage rates, thus failing to meet the requirements for automatic seedling removal and transplanting. Currently, cabbage seedlings transplanted by transplanting machines are usually cultivated using plug trays. The automatic seedling-retrieving transplanting machine directly picks up the cabbage seedlings from the plug trays by grasping the root and stem base. However, although cabbage seedlings cultivated by the ordinary plug tray method have a high germination rate, they are uneven in emergence, prone to etiolation, and have a long hardening period, making them susceptible to damage during machine transplanting. Therefore, seedlings cultivated by the ordinary plug tray method are not suitable for mechanical transplanting. Thus, a new cabbage seedling cultivation method suitable for machine transplanting should be provided. Summary of the Invention

[0003] Therefore, the purpose of this invention is to provide a method for cultivating cabbage seedlings suitable for automatic seedling transplanting machines, which solves the problems of uneven emergence, unreasonable plant height and stem thickness, and long seedling hardening time in current tray cultivation of cabbage seedlings, making it difficult to cultivate cabbage seedlings suitable for transplanting machines.

[0004] The present invention solves the above problems through the following solution:

[0005] A method for raising cabbage seedlings suitable for planting with an automatic seedling transplanter, the method being as follows:

[0006] (1) Seedling trays and disinfection: After disinfecting the rigid seedling trays, fill the seedling substrate into the holes;

[0007] (2) Sowing: After adjusting the humidity of the seedling substrate, sow the disinfected seeds in the center of the hole;

[0008] (3) Seedling stage: After sowing, the seeds are protected from light to promote germination. The daytime temperature is 23-27℃, the nighttime temperature is 20-24℃, and the relative humidity of the air and substrate is 85-95%. Germination continues until the cotyledons emerge from the soil.

[0009] (4) Seedling stage: Maintain daytime temperature of 20-24℃ and nighttime temperature of 14-18℃, relative humidity of air and substrate of 60-70%, and provide appropriate shade until the cotyledons are fully extended;

[0010] (5) Tall seedling treatment: After the cotyledons have extended to two leaves and one heart, shade them. The daytime temperature is 25-27℃, the nighttime temperature is 18-20℃, and the relative humidity of the air and substrate is 80-85%. At the same time, the seedling height treatment is carried out. The tall seedling treatment time is 2-4 days. After the tall seedling treatment is completed, add wood ash substrate again.

[0011] (6) Growth period: After the seedling treatment is completed, control the daytime temperature to be 25-27℃ and the nighttime temperature to be 14-15℃, the relative humidity of air and substrate to be 65-70%, increase the light intensity, and supplement water-soluble fertilizer;

[0012] (7) Hardening period: Maintain the temperature at 16-20℃ during the day and 10-14℃ at night. Maintain the relative humidity of air and substrate at 50-55%. After hardening for 3-5 days, cabbage seedlings suitable for planting with automatic seedling transplanting machines will be obtained.

[0013] Because the cabbage seedlings prepared by this invention need to be suitable for automatic seedling transplanting machines, they differ from ordinary cabbage seedling cultivation. It is necessary to ensure that the seedlings are uniform, tall, and thick in order to reduce damage when they are picked up by the transplanting machine. Therefore, this invention strictly controls the temperature, humidity, and light conditions during the seedling cultivation process and performs seedling height treatment.

[0014] Furthermore, when cultivating mature cabbage seedlings older than 30 days, use 98 or 105-cell trays; when cultivating young cabbage seedlings younger than 30 days, use 128 or 200-cell trays.

[0015] Cabbage seedlings at different cultivation times require different types of seedling trays with different hole sizes, which facilitates management and makes it easier for transplanting machines to pick up the seedlings.

[0016] Furthermore, the seedling substrate is mixed in a mass ratio of perlite: peat moss: mushroom residue of 1:1:2. Before use, 2 kg of compound fertilizer is added to each cubic meter of seedling substrate.

[0017] Sufficient nutrients need to be added to the substrate before seedling cultivation to facilitate seedling growth.

[0018] Furthermore, in step (5), the seedling treatment involves first spraying the cabbage seedlings with brassinolide solution, and then spraying the cabbage seedlings with seedling treatment agent 1-2 days later. After spraying the seedling treatment agent, wood ash substrate is added 1-2 days later.

[0019] The height treatment of this invention is to treat cabbage seedlings during the two-leaf-one-heart stage. First, brassinolide is used in combination with light and temperature to promote the rapid elongation of the cabbage seedling stem, which can quickly accelerate the height of the cabbage seedlings at this stage. However, if this treatment is carried out for a long time, it will cause the cabbage seedlings to grow excessively. Therefore, the height treatment time should be strictly controlled and used in combination with height treatment agents to increase the stem diameter while increasing the stem height, thus promoting the healthy growth of the seedlings.

[0020] Furthermore, the concentration of the brassinolide solution is 0.02-0.025 wt%, the amount of brassinolide solution used is 1 ml / well, and the amount of the seedling growth treatment agent used is 2 ml / well. The concentration and dosage of brassinolide and the seedling growth treatment should be strictly controlled.

[0021] Furthermore, in step (5), the specific operation of adding wood ash substrate after the tall seedling treatment is as follows:

[0022] After the seedlings are treated, spread a 0.5-1cm layer of wood ash substrate, which is a mixture of wood ash and seedling substrate in a mass ratio of 0.5:(1-2), and then water them.

[0023] Furthermore, in step (5), the raw materials for the seedling treatment agent include:

[0024] The ingredients include betaine, urea, choline chloride, magnesium hydroxide, hydrolyzed gelatin, tannic acid, and chitosan.

[0025] Furthermore, the mass ratio of chitosan, tannic acid, magnesium hydroxide, betaine, choline chloride, urea, and hydrolyzed gelatin is (3-4):1:(0.3-0.5):(0.1-0.2):(1.2-1.3):1:0.5.

[0026] Furthermore, the preparation method of the seedling treatment agent is as follows:

[0027] (1) Add magnesium hydroxide to a 2-3 wt% tannic acid solution, stir for 1-2 hours and let stand overnight, then add 3-4 wt% chitosan solution and betaine, stir evenly to obtain a mixed hydrogel;

[0028] (2) After mixing choline chloride and urea, heat the mixture in a water bath to 80°C and stir for 60 min. After cooling, add 10-15 wt% hydrolyzed gelatin solution. After stirring evenly, add mixed hydrogel, heat in a water bath to 40-45°C and stir at high speed for 15-20 min. After standing, the high seedling treatment agent is obtained.

[0029] Furthermore, the seedling treatment agent should be diluted 3-5 times before use.

[0030] During the seedling height treatment, the first step is to spray the cabbage seedlings, which are at the two-leaf-one-heart stage, with the plant's endogenous hormone brassinolide to accelerate stem elongation. Because brassinolide has a strong promoting effect, the cabbage seedlings grow too rapidly at this stage. To inhibit this rapid growth, a seedling height treatment agent is added immediately 1-2 days after the brassinolide treatment to slow down the rapid absorption rate of brassinolide by the seedlings, suppressing the high-concentration stimulation of stem growth by brassinolide, and thus switching to a slow and continuous effect. After 1-2 days of treatment, normal cultivation is carried out to allow the seedlings to return to a normal growth state, followed by hardening-off treatment. Therefore, the seedling height treatment agent of this invention needs to first adsorb brassinolide and then release it slowly.

[0031] Chitosan in the seedling treatment agent contains a large number of active groups, which can form a gel with excellent release performance and suitable strength. However, it does not have the function of self-adsorbing drugs. Furthermore, if chitosan is directly mixed with tannic acid, its molecular chains usually instantly combine to form clusters or flocculent gels, resulting in unstable chemical properties and making it more prone to sudden drug release. Therefore, this invention uses magnesium hydroxide particles to first undergo an charge neutralization reaction in a tannic acid solution to adsorb tannic acid, and then mixes it with chitosan and betaine to form a mixed hydrogel. The ionic liquid formed by choline chloride and urea in the seedling treatment agent has broad solubility characteristics, which can adsorb residual brassinolide, preventing the continuous high concentration of brassinolide from acting on seedlings. At the same time, the ionic liquid can release the tannic acid adsorbed by magnesium hydroxide, promoting the slow self-assembly of tannic acid and chitosan to form a relatively viscous liquid seedling treatment agent, achieving the purpose of adsorbing and releasing brassinolide. In addition, direct contact of ionic liquids with seedlings can damage the seedling epidermis. Therefore, combining ionic liquids with hydrolyzed gelatin to form a viscous liquid not only allows for better and more uniform mixing with the mixed hydrogel, but also reduces the concentration of the ionic liquid, preventing direct contact with the seedlings. This achieves the goal of both rapidly adsorbing brassinolide and preventing damage to the seedlings.

[0032] Therefore, when a seedling growth regulator is applied to cabbage seedlings, it rapidly absorbs and enriches the brassinolide that was not absorbed on the surface of the cabbage, preventing prolonged high-concentration stimulation of the seedlings, which could cause excessive growth and damage to seedling health. Simultaneously, the gelling agent slowly releases the brassinolide, allowing it to act gradually on the seedlings and promote continued growth. After the seedling growth regulator is applied, a certain amount of wood ash should be sprinkled on top, followed by watering. This dissolves the alkaline substances in the wood ash and reacts with the seedling growth regulator, completely stopping the stimulation of the seedlings and allowing for normal growth and development during the vegetative growth and hardening-off periods.

[0033] Beneficial effects:

[0034] This invention cultivates cabbage seedlings suitable for automatic seedling transplanting machines by using a seedling treatment agent and strictly controlling the temperature, humidity, and light conditions during the seedling cultivation process. The cultivated seedlings have the advantages of tall plants, thick stems, and high survival rate, making them suitable for machine transplanting and contributing to the expansion of the cabbage industry and the development of mechanized agriculture. Attached Figure Description

[0035] Figure 1 Seedling raising process diagram;

[0036] Figure 2 Cabbage seedlings during their growth period were grown in water (left) and in water (right).

[0037] Figure 3 Transplanter transplants cabbage seedlings. Detailed Implementation

[0038] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings:

[0039] Unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods. Unless otherwise specified, the materials and reagents used in the embodiments of this invention are commercially available.

[0040] Example 1:

[0041] Weigh the raw materials according to the following mass:

[0042] 3g chitosan (80% deacetylation), 1g tannic acid, 0.3g magnesium hydroxide powder (particle size approximately 0.5 micrometers), 0.1g betaine, 1.2g choline chloride, 1g urea, 0.5g hydrolyzed gelatin.

[0043] (1) After adding water to tannic acid to make a 2wt% tannic acid solution, magnesium hydroxide powder was added, and the mixture was stirred for 1 hour and then left to stand overnight. Then, a 3wt% chitosan solution made of chitosan and 1wt% acetic acid solution and betaine were added and stirred evenly to obtain a mixed hydrogel.

[0044] (2) After mixing choline chloride and urea, heat the mixture in a water bath to 80°C and stir for 60 min. After cooling, add 10 wt% hydrolyzed gelatin solution to obtain a mixed hydrogel after stirring evenly. Heat the mixture in a water bath to 40°C and stir at high speed for 15 min. Let it stand overnight as a high seedling treatment agent.

[0045] Example 2:

[0046] Weigh the raw materials according to the following mass:

[0047] 3.5g chitosan (80% deacetylation), 1g tannic acid, 0.4g magnesium hydroxide powder (particle size about 0.5 micrometers), 0.15g betaine, 1.2g choline chloride, 1g urea, 0.5g hydrolyzed gelatin.

[0048] (1) After adding water to tannic acid to make a 2.5wt% tannic acid solution, magnesium hydroxide powder was added, and the mixture was stirred for 1.5h and then left to stand overnight. Then, a 3.5wt% chitosan solution made of chitosan and 1wt% acetic acid solution and betaine were added and stirred evenly to obtain a mixed hydrogel.

[0049] (2) After mixing choline chloride and urea, heat the mixture in a water bath to 80°C and stir for 60 min. After cooling, add 12 wt% hydrolyzed gelatin solution to obtain a mixed hydrogel after stirring evenly. Heat the mixture in a water bath to 45°C and stir at high speed for 20 min. Let it stand overnight as a high seedling treatment agent.

[0050] Example 3:

[0051] Weigh the raw materials according to the following mass:

[0052] 4g chitosan (80% deacetylation), 1g tannic acid, 0.5g magnesium hydroxide powder (particle size approximately 0.5 micrometers), 0.2g betaine, 1.3g choline chloride, 1g urea, 0.5g hydrolyzed gelatin.

[0053] (1) After adding water to tannic acid to make a 3wt% tannic acid solution, magnesium hydroxide powder was added, and the mixture was stirred for 2 hours and then left to stand overnight. Then, a 4wt% chitosan solution made of chitosan and 1wt% acetic acid solution and betaine were added and stirred evenly to obtain a mixed hydrogel.

[0054] (2) After mixing choline chloride and urea, heat the mixture in a water bath to 80°C and stir for 60 min. After cooling, add 15 wt% hydrolyzed gelatin solution to obtain a mixed hydrogel after stirring evenly. Heat the mixture in a water bath to 45°C and stir at high speed for 20 min. Let it stand overnight as a high seedling treatment agent.

[0055] Comparative Example 1:

[0056] The seedling treatment agent prepared in this comparative example is compared with that in Example 1, the difference being that magnesium hydroxide treatment is not used in step (1). The specific operation is as follows:

[0057] (1) Tannic acid is mixed with water to make a 2wt% tannic acid solution, which is then mixed with chitosan and a 1wt% acetic acid solution to make a 3wt% chitosan solution, and betaine. After stirring evenly, a mixed hydrogel is obtained.

[0058] The subsequent preparation steps are the same.

[0059] Comparative Example 2:

[0060] The seedling treatment agent prepared in this comparative example is compared with that in Example 1. The difference is that tannic acid is not added in step (1), but a certain amount of crosslinking agent is added. The specific operation process is as follows:

[0061] (1) A 3.5 wt% chitosan solution was prepared by mixing chitosan with 1 wt% acetic acid solution, and betaine was added. Then 0.1 g of ethylene glycol dimethacrylate (EGDMA) was added for cross-linking. After stirring evenly, a mixed hydrogel was obtained.

[0062] The subsequent preparation steps are the same.

[0063] Comparative Example 3:

[0064] The seedling treatment agent prepared in this comparative example is compared with that in Example 1. The difference is that choline chloride and urea are not added in step (2). The specific operation process is as follows:

[0065] (2) Mix 12wt% hydrolyzed gelatin solution with mixed hydrogel, heat in a water bath to 45℃ and stir at high speed for 20 minutes, then let stand overnight for seedling treatment.

[0066] Comparative Example 4:

[0067] The seedling treatment agent prepared in this comparative example is compared with that in Example 1. The difference is that hydrolyzed gelatin is not added in step (2). The specific operation process is as follows:

[0068] (2) After mixing choline chloride and urea, heat the mixture in a water bath to 80°C and stir for 60 min. After cooling, add the mixed hydrogel, heat the mixture in a water bath to 45°C and stir at high speed for 20 min. Let it stand overnight as a high seedling treatment agent.

[0069] Comparative Example 5:

[0070] The seedling treatment agent prepared in this comparative example is compared with that in Example 1. The difference is that the mass ratio of raw material chitosan to tannic acid in step (1) is increased to 5:1, specifically the amount of chitosan used is 5g and the amount of tannic acid is 1g, while the rest of the process remains unchanged.

[0071] Comparative Example 6:

[0072] The seedling growth regulator prepared in this comparative example is compared with that in Example 1, the difference being that the seedling growth regulator is prepared using the following method:

[0073] Choline chloride and urea were mixed and heated in a water bath to 80°C. The mixture was stirred for 60 minutes. After cooling, a 3wt% chitosan solution was added, which was prepared by mixing chitosan with 1wt% acetic acid solution. After stirring evenly, tannic acid was added and water was added to prepare a 2wt% tannic acid solution. The mixture was then heated in a water bath to 40°C and stirred at high speed for 15 minutes. The mixture was then left to stand overnight as a seedling treatment agent.

[0074] Example 4:

[0075] (1) Seedling trays and disinfection: After disinfecting the rigid seedling trays, fill the seedling substrate into the holes;

[0076] The seedling substrate is mixed in a mass ratio of perlite: peat moss: mushroom residue of 1:1:2. The pH can be adjusted to 6.0-6.5. After mixing, add 2 kg of compound fertilizer for seedling cultivation to each cubic meter of seedling substrate, stir well and then fill the seedling trays.

[0077] Use 98 or 105-cell trays when cultivating mature cabbage seedlings that are over 30 days old; use 128 or 200-cell trays when cultivating young cabbage seedlings that are under 30 days old.

[0078] (2) Sowing: After adjusting the humidity of the seedling substrate, it should be able to be squeezed into a ball in your hand. Sow the disinfected seeds in the seedling trays, one seedling per hole;

[0079] (3) Seedling emergence period: After sowing, the seeds are protected from light to promote germination. The daytime temperature is 23-27℃, the nighttime temperature is 20-24℃, and the relative humidity of the air and substrate is 85-95%. Germination continues until the cotyledons emerge from the soil, which usually takes about 2-3 days.

[0080] (4) Seedling stage: Maintain daytime temperature of 20-24℃, nighttime temperature of 14-18℃, relative humidity of air and substrate of 60-70%, shading rate of 30-35%, and light time of 13-14h until the cotyledons are fully extended, usually 3-4 days.

[0081] (5) Seedling height treatment: After the cotyledons have extended to two leaves and one heart, shade them to avoid direct sunlight. The daytime temperature is 25-27℃, the nighttime temperature is 18-20℃, the relative humidity of air and substrate is 80-85%, and the light time is 13-14h. At the same time, seedling height treatment is carried out. Specifically, spray the seedlings with a 0.02-0.025wt% brassinolide solution, with a dosage of about 1ml / hole / day. After 1-2 days of treatment, spray with a seedling height treatment agent, with a dosage of 2ml / hole / day. After 1-2 days of treatment, spread a 0.5-1cm layer of wood ash substrate mixed with seedling substrate in a mass ratio of 0.5:(1-2), and then water it to complete the seedling height treatment.

[0082] (6) Growth period: After the seedling treatment is completed, control the daytime temperature to be 25-27℃ and the nighttime temperature to be 14-15℃. The relative humidity of air and substrate should be 65-70%. Increase the light intensity to be greater than 35000lx and the light duration to be 12h. Supplement with water-soluble fertilizer containing trace elements with EC value ≤0.9mS / cm once or twice, usually every 14-16 days.

[0083] (7) Hardening-off period: Maintain the temperature at 16-20℃ during the day and 10-14℃ at night. Maintain the relative humidity of air and substrate at 50-55%. The light duration is 16 hours and the light intensity is greater than 40000lx. During this period, supplement with water-soluble fertilizer containing trace elements with an EC value ≤1mS / cm once or twice. After hardening off for 3-5 days, cabbage seedlings suitable for transplanting can be obtained.

[0084] Example 5: Cabbage Seedling Experiment

[0085] A seedling raising experiment for Zhonggan 21 was conducted, and the seedling raising process was referenced in Example 4:

[0086] (1) Seedling trays and disinfection: After disinfecting the seedling trays, fill the seedling substrate into the holes;

[0087] (2) Sowing: After adjusting the humidity of the seedling substrate, it should be able to be squeezed into a ball in your hand and crumble when released. Sow the sterilized seeds in the seedling trays, one seedling per hole.

[0088] (3) Germination period: After sowing, the seeds are protected from light to promote germination. The daytime temperature is 25℃, the nighttime temperature is 22℃, and the relative humidity of the air and substrate is 85-90%. The treatment is completed after 3 days.

[0089] (4) Seedling period: Maintain daytime temperature of 23℃, nighttime temperature of 16℃, relative humidity of air and substrate of 60-70%, shading rate of 35%, light duration of 14h, intensity of greater than 25000lx, and end treatment after 3 days;

[0090] (5) Seedling height treatment: The daytime temperature is 26℃, the nighttime temperature is 19℃, the relative humidity of air and substrate is 80-85%, the light duration is 14h, the intensity is greater than 25000lx, and seedling height treatment is carried out at the same time. Specifically, the seedlings are first sprayed with a 0.02wt% brassinolide solution, with a usage of about 1ml / hole / day. After 2 days of treatment, the seedling height treatment agent prepared and diluted 3 times is sprayed, with a usage of 2ml / hole / day. After 2 days of treatment, a 0.5cm layer of wood ash substrate mixed with seedling substrate in a mass ratio of 0.5:1 is spread, and then watering is carried out. Watering is sufficient to complete the seedling height treatment. The total treatment lasts for 4 days.

[0091] (6) Growth period: After the seedling treatment is completed, control the daytime temperature to be 26℃ and the nighttime temperature to be 15℃. The relative humidity of air and substrate is 65-70%. Increase the light intensity to be greater than 35000lx and the light duration to be 12h. Supplement with water-soluble fertilizer containing trace elements with EC value ≤0.9mS / cm once. The treatment lasts for 14 days.

[0092] (7) Hardening period: Maintain the temperature at 18℃ during the day and 12℃ at night. Maintain the relative humidity of air and substrate at 50-55%. The light duration is 16 hours and the light intensity is greater than 40000lx. During this period, supplement with water-soluble fertilizer containing trace elements with an EC value ≤1mS / cm once. The hardening treatment ends after 3 days.

[0093] The experiment consisted of 11 groups, with 200 plants in each group and three replicates. Experimental group 1 used the seedling treatment agent prepared in Example 1, control groups 1-6 used the seedling treatment agent prepared in Comparative Examples 1-6, control groups 7-8 used the seedling treatment agent prepared in Example 1 but with different treatment times, control group 9 used only brassinolide, and the CK group was not treated with the seedling treatment agent and used water as a control.

[0094] The tall seedling treatment process for control group 7 was carried out during the seedling stage, and the specific steps are as follows:

[0095] (4) Seedling stage: Maintain a daytime temperature of 23℃ and a nighttime temperature of 16℃, a relative humidity of 60-70% for air and substrate, a shading rate of 35%, a light duration of 14h, and an intensity greater than 25000lx. At the same time, perform seedling height treatment. Specifically, spray the seedlings with a 0.02wt% brassinolide solution at a rate of about 1ml / well / day. After 2 days of treatment, spray the seedling height treatment agent diluted 3 times at a rate of 2ml / well / day. After 2 days of treatment, spread a 0.5cm layer of wood ash substrate mixed with seedling substrate at a mass ratio of 0.5:1. Then water the seedlings thoroughly. The seedling height treatment is completed. The seedling stage lasts for a total of 7 days. The seedlings then enter the growth stage directly.

[0096] The tall seedling treatment process for control group 8 was carried out during the growing season, and the specific steps are as follows:

[0097] (4) Seedling period: Maintain daytime temperature of 23℃, nighttime temperature of 16℃, relative humidity of air and substrate of 60-70%, shading rate of 35%, light duration of 14h, intensity of greater than 25000lx, and end treatment after 3 days;

[0098] (5) Growth period: Control the daytime temperature to 26℃ and the nighttime temperature to 15℃, and the relative humidity of the air and substrate to 65-70%. Increase the light intensity to greater than 35000lx and the light duration to 12h. At the same time, carry out seedling treatment. Specifically, spray the seedlings with a 0.02wt% brassinolide solution at a rate of about 1ml / hole / day. After 2 days of treatment, spray the seedling treatment agent diluted 3 times at a rate of 2ml / hole / day. After 2 days of treatment, spread a 0.5cm layer of wood ash substrate mixed with seedling substrate at a mass ratio of 0.5:1. Then water the seedlings thoroughly. After seedling treatment, supplement with water-soluble fertilizer containing trace elements with an EC value ≤0.9mS / cm once every 5 days or more. The total growth period is 18 days.

[0099] Control group 9:

[0100] (5) Seedling height treatment: The daytime temperature is 26℃, the nighttime temperature is 19℃, the relative humidity of air and substrate is 80-85%, the light duration is 14h, the intensity is greater than 25000lx, and seedling height treatment is carried out at the same time. The seedlings are sprayed with a 0.01wt% brassinolide solution, with a usage of about 1ml / well / day, for 1 day. Then, the seedlings are sprayed with 0.005wt% brassinolide, with a usage of about 1ml / well / day, for 1 day. After spraying, the seedlings are cultivated in a conventional manner for 2 days. The total cultivation period is 4 days.

[0101] Thirty seedlings were randomly selected from each group to measure the height of cabbage seedlings during the seedling stage, the seedling treatment stage, and the growth stage. After the hardening-off period, the height, stem diameter, and survival rate of cabbage seedlings were measured. The average values ​​are shown in Table 1.

[0102] Table 1

[0103]

[0104] Forty cabbage seedlings from each of the above groups were selected and transplanted using a transplanter. After being managed in the same way, the survival rate of each group was counted on the 7th day after transplanting. The data are shown in Table 2.

[0105] Table 2

[0106] Serial Number Group Survival rate (%) Serial Number Group Survival rate (%) 1 Experimental group 1 97.5 6 Control group 5 94.5 2 Control group 1 95.75 7 Control group 6 89.75 3 Control group 2 93.25 8 Control group 7 85.75 4 Control group 3 88 9 control group 8 91.25 5 Control group 4 92.25 10 Control group 9 81.25 11 CK 91

[0107] Analysis of the data in Tables 1 and 2 shows that:

[0108] 1. The seedling height of the experimental group was roughly the same as that of the control group during the seedling stage. However, after the tall seedling treatment, the plant height of the experimental group increased significantly, reaching 14.1 cm during the hardening-off period, and the stem diameter also reached 3.67 mm. This indicates that the cabbage seedlings treated with the tall seedling treatment were tall and robust, making them particularly suitable for automated transplanting machines. In contrast, the control group 9 only received brassinolide gradient treatment, which resulted in rapid growth of the cabbage seedlings after the tall seedling treatment. However, by the end of the hardening-off period, the stems of the seedlings were thin, indicating excessive growth. Therefore, the survival rate of the seedlings was low after the final hardening-off period, and their weak seedlings also resulted in a low survival rate after machine transplanting.

[0109] 2. In the preparation of the seedling height treatment agent, compared with the experimental group, control group 1 did not add magnesium hydroxide. After the seedling height treatment, the plant height began to be lower than that of the experimental group. This is because magnesium hydroxide has an adsorption effect on tannic acid, preventing the rapid formation of flocculent matter after the chitosan and tannic acid are mixed, which would lead to unstable chemical properties of the prepared mixed hydrogel, making it difficult to achieve the purpose of adsorbing and releasing brassinolide after the seedling height treatment agent is made. Control group 2 did not add tannic acid. Although the chitosan solution itself has a certain viscosity, the absence of tannic acid makes it difficult for chitosan to form a gel, reducing the ionic liquid and reducing the slow-release properties, thus resulting in lower plant height. Control group 3 did not add choline chloride and urea, resulting in tall but weak seedlings with a low survival rate. This is because the addition of ionic liquid can not only dissolve tannic acid and brassinolide to achieve the purpose of slow-release of brassinolide, but urea and choline chloride also have certain growth regulation functions, which can promote the growth of cabbage seedlings.

[0110] 3. In the preparation of the seedling growth regulator, control group 4 did not add hydrolyzed gelatin, control group 5 increased the amount of chitosan, and control group 6 directly mixed chitosan gel with ionic liquid. The overall growth and survival rate of the cabbage seedlings in control group 6 were worse than those in the experimental group. This is because gelatin can not only better mix the ionic liquid with the mixed hydrogel, but also reduce the concentration of the ionic liquid and prevent direct contact with the seedlings. In addition, when chitosan reacts with tannic acid, an appropriate amount of chitosan and hydrolyzed gelatin can also improve the performance of chitosan to a certain extent, thereby improving the adsorption-slow release performance of the seedling growth regulator. When chitosan is excessive or directly mixed with ionic liquid, the slow release performance is too slow and the gel viscosity is too high, which hinders the effect of the growth regulator on the seedlings, resulting in unsuitable seedling height and stem thickness, and a low survival rate when transplanted.

[0111] 4. When performing height treatment, it is best to do so between the seedling stage and the growth stage, when the cabbage seedlings are in the two-leaf-one-heart stage, to accelerate the elongation of the stem. Because brassinolide has a strong promoting effect, early treatment will cause the seedlings to grow faster in the initial stage, but subsequent growth will be slowed down, resulting in weak seedlings. Delayed treatment will cause the seedlings to grow taller but not thicker, and the leaves will turn yellowish, ultimately leading to a low survival rate.

[0112] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A method for raising cabbage seedlings suitable for planting with an automatic seedling transplanter, characterized in that, The seedling cultivation method is as follows: (1) Seedling trays and disinfection: After disinfecting the rigid seedling trays, fill the seedling substrate into the holes; (2) Sowing: After adjusting the humidity of the seedling substrate, sow the disinfected seeds in the center of the hole; (3) Seedling stage: After sowing, the seeds are protected from light to promote germination. The daytime temperature is 23-27℃, the nighttime temperature is 20-24℃, and the relative humidity of the air and substrate is 85-95%. Germination continues until the cotyledons emerge from the soil. (4) Seedling stage: Maintain daytime temperature of 20-24℃ and nighttime temperature of 14-18℃, relative humidity of air and substrate of 60-70%, and provide appropriate shade until the cotyledons are fully extended; (5) Tall seedling treatment: After the cotyledons have extended to two leaves and one heart, shade them. The daytime temperature is 25-27℃, the nighttime temperature is 18-20℃, and the relative humidity of the air and substrate is 80-85%. At the same time, the seedling height treatment is carried out. The tall seedling treatment time is 2-4 days. After the tall seedling treatment is completed, add wood ash substrate again. (6) Growth period: After the seedling treatment is completed, control the daytime temperature to be 25-27℃ and the nighttime temperature to be 14-15℃, the relative humidity of air and substrate to be 65-70%, increase the light intensity, and supplement water-soluble fertilizer; (7) Hardening-off period: Maintain the temperature at 16-20℃ during the day and 10-14℃ at night. Maintain the relative humidity of air and substrate at 50-55%. After hardening off for 3-5 days, cabbage seedlings suitable for planting with automatic seedling transplanter will be obtained. In step (5), the seedling treatment involves first spraying the cabbage seedlings with brassinolide solution, and then spraying the cabbage seedlings with seedling treatment agent 1-2 days later. After spraying the seedling treatment agent, wood ash substrate is added 1-2 days later. The concentration of the brassinolide solution is 0.02-0.025 wt%, the amount of brassinolide solution used is 1 ml / well, and the amount of the seedling treatment agent used is 2 ml / well; The mass ratio of the raw materials chitosan, tannic acid, magnesium hydroxide, betaine, choline chloride, urea, and hydrolyzed gelatin in the high seedling treatment agent is (3-4):1:(0.3-0.5):(0.1-0.2):(1.2-1.3):1:0.5; In step (5), the specific operation of adding wood ash substrate after the tall seedling treatment is as follows: After the seedlings are treated, a 0.5-1cm layer of wood ash substrate is spread, which is a mixture of wood ash and seedling substrate in a mass ratio of 0.5:(1-2), and then watering is carried out. The preparation method of the seedling treatment agent is as follows: (1) Add magnesium hydroxide to a 2-3 wt% tannic acid solution, stir for 1-2 hours and let stand overnight, then add 3-4 wt% chitosan solution and betaine, stir evenly to obtain a mixed hydrogel; (2) After mixing choline chloride and urea, heat the mixture in a water bath to 80°C and stir for 60 min. After cooling, add 10-15 wt% hydrolyzed gelatin solution, stir evenly, add mixed hydrogel, heat in a water bath to 40-45°C, stir at high speed for 15-20 min, and let stand to obtain the high seedling treatment agent.

2. The method for raising cabbage seedlings suitable for planting with an automatic seedling transplanter according to claim 1, characterized in that, When cultivating mature cabbage seedlings older than 30 days, use 98 or 105-cell trays; when cultivating young cabbage seedlings younger than 30 days, use 128 or 200-cell trays.

3. The method for raising cabbage seedlings suitable for planting with an automatic seedling transplanter according to claim 2, characterized in that, The seedling substrate is mixed in a mass ratio of perlite: peat moss: mushroom residue of 1:1:

2. Before use, 2 kg of compound fertilizer is added to each cubic meter of seedling substrate.

4. The method for raising cabbage seedlings suitable for planting with an automatic seedling transplanter according to claim 3, characterized in that, The seedling treatment agent is diluted 3-5 times before use.

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