Seedling-raising agent, seedling-raising substrate and rice seedling-raising method

Abstract

The present invention provides a rice seedling raising method. The specific steps include first weighing nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate according to a mass ratio of 4000:25:(0.5 - 2):(0.5 - 2), mixing them, controlling the water content to be 10% - 15%, and retting for 10 - 25 days to obtain a seedling raising substrate; uniformly covering the seedling raising substrate in a seedling tray and sowing pre-treated rice seeds, and then carrying out seedbed management according to the standard of protected carpet seedling raising. This method can reduce the incidence rate of rice seedlings in the protected area to less than 0.05%, and the root-shoot ratio of the rice seedlings is relatively large and the number of yellow roots is small, effectively improving the low-temperature resistance and disease resistance of the rice seedlings. The present invention also provides a seedling raising agent and a seedling raising substrate, which can improve the ability of the carpet seedling machine-transplanted seedlings in protected areas such as multi-span greenhouses, plastic greenhouses, and plastic small arch sheds to resist low-temperature persecution, enabling the seedling raising in the early spring low-temperature environment to have the ability to resist the cold snap in spring.

Description

Technical Field

[0001] The present invention relates to the technical field of rice seedling raising, and specifically, it relates to a seedling raising agent, a seedling raising substrate and a rice seedling raising method. Background Art

[0002] With the popularization and promotion of the high-yield technology of protected early seedling raising, the ratooning rice technology, and the mechanized seedling transplanting technology, the traditional temperature index limit for seedling raising when the average temperature exceeds 12°C has been replaced by the index limit that seedling raising can be carried out when the average temperature exceeds 5°C. However, when raising seedlings in the early spring low-temperature environment of 5°C to 12°C, it is easy to suffer from pathological rotten seedlings.

[0003] Currently, when cultivating machine-transplanted carpet seedlings above 12°C, in order to improve the quality of seedlings and the survival rate of seedlings after transplanting, in many areas during seedling raising, a strong seedling agent is often mixed into the nutrient soil to improve the soil environment. For example, the common method of applying the strong seedling agent by broadcasting includes leveling the bedding, placing the trays and spreading the soil, spreading the strong seedling agent after spreading the soil, spraying water with a micro-sprinkler, pressing the germinated seeds and covering the soil after sowing the germinated seeds; or spreading the strong seedling agent after sowing the bottom soil, then sowing, covering the soil, and then spraying water with a micro-sprinkler on the covered soil. Another example is the invention patent application with the application number 201810907312.9, which specifically discloses a seedling raising method, including composting and fermenting river silt, poultry manure, and straw, and then mixing them with Adiantum capillus-veneris ash, compound fertilizer, and sulfur powder to form a seedling raising method with strong seedlings and high survival rate after throwing seedlings.

[0004] However, the above-mentioned seedling raising methods and means usually have better seedling quality only under the condition of a relatively high temperature environment (average temperature exceeds 12°C), and the seedling raising input cost is relatively high. But for the seedling raising of ratooning rice and early rice machine-transplanted seedlings from March to April every year, that is, during the early spring seedling raising process, "returning cold spells" are often encountered, with continuous low temperature and rainy weather, which are extremely likely to cause phenomena such as rotten seeds, rotten seedlings, and dead seedlings standing, greatly affecting the quality and yield of rice seedlings, and bringing direct economic losses to planting farmers. And the existing seedling raising methods have not effectively alleviated the adverse effects on the growth of seedlings when encountering "returning cold spells" during early spring low-temperature protected seedling raising. Summary of the Invention

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a rice seedling raising method, which belongs to a method for raising machine-transplanted carpet seedlings in a protected area under a low-temperature environment. The specific steps include: first, weighing nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate according to the mass ratio of 4000:25:(0.5 - 2):(0.5 - 2), mixing them, controlling the water content to be 10% - 15%, and then retting for 10 - 25 days to obtain a seedling raising substrate; uniformly covering the seedling raising substrate in the seedling tray and sowing the pre-treated rice seeds, and then carrying out seedbed management according to the standard of protected carpet seedling raising.

[0006] Based on the above, the steps of uniformly covering the seedling-raising substrate and sowing the pretreated rice seeds in the seedling tray include: uniformly covering a layer of the seedling-raising substrate with a thickness of 2 cm to 2.5 cm in the seedling tray as the bottom soil, sowing the pretreated rice seeds on the bottom soil, and then uniformly covering a layer of the seedling-raising substrate with a thickness of 0.3 cm to 0.5 cm on the surface of the bottom soil as the covering soil.

[0007] Based on the above, the nutrient soil is taken from garden soil, mature dryland soil or paddy soil that has been winter-plowed and spring-puddled.

[0008] Based on the above, the steps of retting include piling up the mixed nutrient soil, sulfur powder, urea and potassium dihydrogen phosphate at room temperature, covering with a film on the top, and then standing for 10 d to 25 d.

[0009] Based on the above, the retting time is 19 d to 21 d.

[0010] Based on the above, the steps of nursery bed management according to the standard of protecting carpet seedling raising include:

[0011] The needle-emergence stage is from sowing to the tip of the first leaf showing. During this period, mainly cultivate the seed roots. It is required that the temperature in the protected area does not exceed 32 °C. When it exceeds 32 °C, start ventilation;

[0012] The greening stage is from emergence to the full expansion of the first complete leaf. Control the height of the first leaf sheath above the ground not to exceed 3 cm, and promote the growth of 5 new roots underground. Control the temperature in the protected area at 22 °C to 25 °C;

[0013] The seedling-weaning stage is from the tip of the second leaf showing to the expansion of the third leaf. Promote the growth of new roots underground and control the height of the seedlings above the ground. Control the temperature in the protected area at 20 °C to 22 °C. During this period, increase ventilation and harden the seedlings to reduce humidity;

[0014] The pre-planting period is to control water and squat the seedlings to strengthen the roots, making the seedlings in a state of hunger and thirst; after the seedlings have three leaves and one heart, transplant them.

[0015] Based on the above, the steps of pretreating rice seeds include: first, sun the seeds 5 d to 7 d before soaking. After soaking with the medicament solution for 1 d, carry out seed disinfection. After rinsing the medicament solution clean, transfer to warm water for soaking for 2 d to 3 d, and then carry out germination treatment. Among them, germination needs to go through three stages: high-temperature chest-breaking, constant-temperature germination, and normal-temperature air-drying of buds. When breaking the chest at high temperature, control the temperature at 38 °C and the time at 4 h to 6 h; when germinating at a constant temperature, control the temperature at 25 °C to 30 °C and the time at 18 h to 20 h.

[0016] The present invention also provides a seedling-raising substrate, which is prepared by retting nutrient soil, sulfur powder, urea and potassium dihydrogen phosphate for 10d to 25d at a water content of 10% to 15%. The mass ratio of the nutrient soil, sulfur powder, urea and potassium dihydrogen phosphate is 4000:25:(0.5 to 2):(0.5 to 2); the nutrient soil is taken from garden soil, mature dry land soil or paddy soil that has been winter-plowed and spring-puddled.

[0017] The present invention also provides a seedling-raising agent, which includes sulfur powder, urea and potassium dihydrogen phosphate.

[0018] Based on the above, the mass ratio of the sulfur powder, the urea and the potassium dihydrogen phosphate is 25:(0.5 to 2):(0.5 to 2).

[0019] Among them, when the seedling-raising agent is used, 4 kg of nutrient soil is added to 1 part of the seedling-raising agent for use, and the trade name is Low-temperature Seedling-raising Ling.

[0020] The present invention has outstanding substantial features and remarkable progress compared with the prior art. Specifically, when raising rice seedlings by machine transplanting in the early spring low-temperature protected ground environment, if encountering the "return of cold spell" weather, due to the low temperature and rainy weather, the viability of the seed embryo will decline, and the "maltose phenomenon" will occur during the emergence period of the rice seeds, resulting in hindered germination and emergence. The quality of the seedlings is weak and vulnerable to diseases such as damping-off. The seedlings cannot take root normally, and the growth of the emerged seedlings will also be inhibited, showing albino seedlings. Because the photosynthesis of the seedlings under low temperature and low light is weakened and the synthesis of chlorophyll is blocked, in severe cases, the seeds and seedlings will rot. Secondly, after the return of cold spell, when the temperature rises, if the temperature rises greatly, that is, suddenly turns sunny, the seedlings will have physiological water loss due to weak root water absorption ability and large transpiration consumption, leading to physiological blight, especially the seedlings around the three-leaf stage are extremely vulnerable to being infected by pathogens and showing damping-off. At the same time, the low temperature and rainy weather will also slow down the evaporation of water vapor, causing waterlogging and oxygen deficiency in the seedling bed. A large amount of nutrients in the endosperm are consumed by the respiration of the seedlings, and reducing substances are produced to poison the seedlings. The disease resistance of the seedlings is weakened, and saprophytic molds will take the opportunity to invade and infect, inducing seedling diseases.

[0021] In view of the above situation, this case proposes a seedling-raising agent, a seedling-raising substrate and a rice seedling-raising method. Specifically, sulfur powder, urea, potassium dihydrogen phosphate are mixed with nutrient soil and then used after being retted, and the rice seeds are placed between the upper and lower layers of the seedling-raising substrate by the method of covering soil with upper and lower interlayers, so as to solve the problems of low-temperature cold damage and damping-off caused by late spring cold snaps. The test results show that when raising rice seedlings in a protected area, without using any pesticides, if encountering low-temperature hazards, the incidence rate of rice seedlings can reach more than 60%. After adopting the rice seedling-raising method provided by the present invention, the incidence rate of rice seedlings in the protected area can be reduced to within 0.05%. The incidence rate is relatively low, the root-shoot ratio of rice seedlings is relatively large, and the number of yellow roots is relatively small, realizing safe seedling-raising in the early spring low-temperature environment, effectively improving the low-temperature tolerance of rice seedlings, thus creating good preconditions for improving the seedling survival rate and seedling quality of machine-transplanted seedlings in the follow-up, and having the effect of low cost compared with other seedling-raising substrates.

[0022] Specifically, in the rice seedling-raising method provided in this case, sulfur powder, urea, potassium dihydrogen phosphate are mixed with nutrient soil and then retted to be used as bottom soil and covering soil for mat-type seedling-raising. After the retting treatment, sulfur powder, urea, potassium dihydrogen phosphate and nutrient fine soil can be fully fused and adsorbed to achieve the purpose of full decomposition. After watering, nutrients are not easily lost through the small holes at the bottom of the seedling tray, and nutrients are not easily volatilized. At the same time, because the bottom soil and the covering soil have the same composition, it can isolate the influence of the external adverse environment on the rice seeds by using the upper covering soil before the germination of the rice seeds, and can ensure that the rice can normally emerge, stand upright and take root in time at low temperature, avoiding the "maltose phenomenon" during the emergence period of rice seeds. After the germination of rice seeds, it can provide a uniform nutrient environment for the roots of rice seedlings up and down, promote the comprehensive distribution of rice roots in the nutrient soil, facilitate the rooting of seedlings and increase the total number of roots, root length and underground dry weight, reduce the yellow root phenomenon caused by malnutrition and avoid the occurrence of albino seedlings, thereby increasing the root-shoot ratio and realizing the improvement of the ability of rice seedlings to resist low-temperature persecution.

[0023] More specifically, the potassium dihydrogen phosphate after retting can not only increase the phosphorus and potassium required for seedling growth, but also enhance the activity of cells, promote the synthesis of substances such as proteins, carbohydrates, amino acids, and vitamins, and all of the above substances can promote the photosynthesis of plants. After retting, part of the urea will be degraded into ammonium nitrogen and converted into nitrate nitrogen through microbial transformation, greatly reducing the possibility of burning seedlings. In addition, the fermented urea will generate a nitrogen-containing nutrient solution, providing carbon, nitrogen and other nutrients for the microorganisms in the fermentation process, improving the fermentation effect of the rice seedling raising substrate, and promoting the absorption of nutrients by the seedlings from the substrate. That is, the retted urea and potassium dihydrogen phosphate can both rapidly improve the photosynthesis ability of crops, promote the activity of various enzymes in plant cells, accelerate the synthesis of substances such as proteins and amino acids, make the leaves of rice seedlings thicker, the leaf age larger, the concentration of cell protoplasm increased, the roots of rice seedlings more developed, and the number of yellow roots less, and can significantly improve the cold resistance of plants. Thus, it can avoid the phenomenon of physiological water loss and the occurrence of physiological blight caused by the weak water absorption ability of the seedling roots and large transpiration consumption when the temperature rises after the late spring cold snap.

[0024] More importantly, in the rice seedling raising method provided in this case, the fermented sulfur powder can be evenly dispersed in the seedling raising substrate, which can effectively inhibit the invasion and infection of saprophytic molds, inhibit the diseases induced by them in the seedlings, and improve the disease resistance of the seedlings. Thus, it can avoid the phenomenon that saprophytic molds take the opportunity to invade and infect due to waterlogging and oxygen deficiency in the seedling field and the weakened disease resistance of the seedlings. Therefore, the seedling raising agent, the seedling raising substrate and the rice seedling raising method can improve the ability of the seedlings raised by the machine transplanting of carpet seedlings in protected areas such as multi-span greenhouses, plastic greenhouses, and plastic small arch greenhouses to resist low-temperature persecution, enabling the seedling raising in the early spring low-temperature environment to have the ability to resist the late spring cold snap. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It shows the growth situation of rice seedlings cultivated with the seedling raising substrate and the soil covering method provided in Examples 1 to 4 under an artificial low-temperature environment.

[0026] Figure 2 It is a summary comparison chart of the growth situation of rice seedlings cultivated with the seedling raising substrate and the soil covering method provided in Examples 1 to 4 and Comparative Test Groups 1 to 2 under artificial low temperature.

[0027] Figure 3 It shows the growth situation of rice seedlings cultivated with the seedling raising substrate and the soil covering method provided in Comparative Test Group 1 under artificial low temperature. DETAILED DESCRIPTION OF THE INVENTION

[0028] The technical solutions of the present invention will be further described in detail below through specific embodiments.

[0029] Example 1

[0030] This embodiment provides a rice seedling raising method, and the specific steps include: First, weigh sulfur powder, urea, and potassium dihydrogen phosphate according to the standard that each portion of the seedling raising agent contains 25 g of sulfur powder, 0.5 g of urea, and 0.5 g of potassium dihydrogen phosphate; and weigh the nutrient soil according to the standard of adding 1 portion of the seedling raising agent per 4 kg, and then mix the weighed nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate, control the water content to 15%, and stuff for 20 d to obtain the seedling raising substrate;

[0031] Cover a layer of the seedling raising substrate in the seedling tray as the bottom soil, then broadcast the pretreated rice seeds on the bottom soil, and then cover another layer of the seedling raising substrate in the seedling tray as the covering soil. Finally, carry out seedbed management according to the standard of protecting carpet seedlings. Among them, control the thickness of the bottom soil to be 2 cm - 2.5 cm, and the thickness of the covering soil to be 0.3 cm - 0.5 cm. Among them, the nutrient soil is taken from garden soil, matured dryland soil, or paddy soil that has been winter-plowed and spring-puddled.

[0032] Specifically, the steps of carrying out seedbed management according to the standard of protecting carpet seedlings include:

[0033] The needle-emerging stage is from sowing to the tip of the first leaf showing. During this period, mainly cultivate the seed roots, and require that the temperature in the shed does not exceed 32 °C. When it exceeds 32 °C, start ventilation;

[0034] The greening stage is from emergence to the full expansion of the first complete leaf. Control the height of the first leaf sheath above the ground not to exceed 3 cm, and promote the growth of 5 new roots underground. Control the temperature in the shed at 22 °C - 25 °C;

[0035] The weaning stage is from the tip of the second leaf showing to the expansion of the third leaf. Promote the growth of new roots underground, control the height of the seedlings above the ground, control the temperature in the shed at 20 °C - 22 °C. During this period, increase ventilation and harden the seedlings to reduce humidity;

[0036] The pre-planting period controls water and squats the seedlings to strengthen the roots, making the seedlings in a state of hunger and thirst; after the seedlings have three leaves and one heart, transplant them.

[0037] Specifically, in this embodiment, the steps of pre-treating rice seeds include: First, sun the seeds 5 - 7 days before soaking. Use a liquid medicine to soak the seeds for about 1 day for seed disinfection. After rinsing the liquid medicine clean, transfer to warm water for soaking for 2 - 3 d, and then carry out germination treatment. Among them, germination requires three stages: high-temperature chest breaking, constant-temperature germination, and normal-temperature air-drying of buds. When breaking the chest at high temperature, control the temperature at 38 °C and the time at 4 - 6 h; when germinating at a constant temperature, control the temperature at 25 °C - 30 °C and the time at 18 - 20 h.

[0038] This embodiment also provides a seedling raising substrate, which includes nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate. Among them, the mass ratio of nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate is 4000:25:0.5:0.5. Among them, the nutrient soil is taken from garden soil, matured dryland soil, or paddy soil that has been winter-plowed and spring-puddled.

[0039] The present invention also provides a seedling-growing agent, which includes sulfur powder, urea and potassium dihydrogen phosphate, and the mass ratio of sulfur powder, urea and potassium dihydrogen phosphate is 25:0.5:0.5. The number of the artificial climate chamber simulation late spring cold snap seedling-growing test using this seedling-growing agent and the soil covering method is recorded as SF3.1.

[0040] Example 2

[0041] This example provides a rice seedling-growing method. The specific steps are basically the same as those in Example 1, except that: in this example, first, sulfur powder, urea and potassium dihydrogen phosphate are weighed respectively according to the standard that each portion of the seedling-growing agent contains 25 g of sulfur powder, 1 g of urea and 1 g of potassium dihydrogen phosphate; and nutrient soil is weighed according to the standard of adding 1 portion of the seedling-growing agent per 4 kg, and then the weighed nutrient soil, sulfur powder, urea and potassium dihydrogen phosphate are mixed and the water content is made to be 15% and then retted for 20 d to obtain the seedling-growing substrate.

[0042] This example provides a seedling-growing substrate. The specific components are basically the same as those in Example 1, except that: in this example, the mass ratio of nutrient soil, sulfur powder, urea and potassium dihydrogen phosphate is 4000:25:1:1.

[0043] This example provides a seedling-growing agent. The specific components are basically the same as those in Example 1, except that: in this example, the mass ratio of sulfur powder, urea and potassium dihydrogen phosphate is 25:1:1. The number of the artificial climate chamber simulation late spring cold snap seedling-growing test using this seedling-growing agent and the soil covering method is recorded as SF3.2.

[0044] Example 3

[0045] This example provides a rice seedling-growing method. The specific steps are basically the same as those in Example 1, except that: in this example, first, sulfur powder, urea and potassium dihydrogen phosphate are weighed respectively according to the standard that each portion of the seedling-growing agent contains 25 g of sulfur powder, 1.5 g of urea and 1.5 g of potassium dihydrogen phosphate; and nutrient soil is weighed according to the standard of adding 1 portion of the seedling-growing agent per 4 kg, and then the weighed nutrient soil, sulfur powder, urea and potassium dihydrogen phosphate are mixed and the water content is made to be 15% and then retted for 20 d to obtain the seedling-growing substrate.

[0046] This example provides a seedling-growing substrate. The specific components are basically the same as those in Example 1, except that: in this example, the mass ratio of nutrient soil, sulfur powder, urea and potassium dihydrogen phosphate is 4000:25:1.5:1.5.

[0047] This example provides a seedling-growing agent. The specific components are basically the same as those in Example 1, except that: in this example, the mass ratio of sulfur powder, urea and potassium dihydrogen phosphate is 25:1.5:1.5.

[0048] The number of the artificial climate chamber simulation of cold snap in spring rice seedling raising experiment using this seedling raising agent and soil covering method is recorded as SF3.3.

[0049] Example 4

[0050] This example provides a rice seedling raising method. The specific steps are basically the same as those in Example 1, except that: in this example, first, sulfur powder, urea, and potassium dihydrogen phosphate are weighed respectively according to the standard that each portion of the seedling raising agent contains 25 g of sulfur powder, 2 g of urea, and 2 g of potassium dihydrogen phosphate; and the nutrient soil is weighed according to the standard of adding 1 portion of the seedling raising agent per 4 kg, and then the weighed nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate are mixed and retted for 20 d to obtain the seedling raising substrate.

[0051] This example provides a seedling raising substrate. The specific components are basically the same as those in Example 1, except that: in this example, the mass ratio of the nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate is 4000:25:2:2.

[0052] This example provides a seedling raising agent. The specific components are basically the same as those in Example 1, except that: in this example, the mass ratio of sulfur powder, urea, and potassium dihydrogen phosphate is 25:2:2.

[0053] The number of the artificial climate chamber simulation of cold snap in spring rice seedling raising experiment using this seedling raising agent and soil covering method is recorded as SF3.4.

[0054] Artificial climate chamber simulation of "cold snap in spring" rice seedling raising experiment

[0055] The seedling raising agents, seedling raising substrates, and soil covering methods provided in Examples 1 to 4 and Comparative Test Groups 1 to 2 are respectively used for the artificial climate chamber simulation of cold snap in spring rice seedling raising experiment. One month after sowing, the seedling quality is investigated, including plant height, leaf age, leaf width, root length, number of white roots, number of yellow roots, seedling incidence, aboveground dry weight, and underground dry weight, and the root-shoot ratio is calculated. The specific statistical results are shown in Tables 1, 2, 3, 4, 5, and 6 below. The specific seedling growth conditions are as Figure 1 , Figure 2 , Figure 3 .

[0056] Among them, Control test group 1: This Comparative Test Group 1 provides a rice seedling raising method. The difference between the specific steps and those in Example 1 is that: in this Comparative Test Group 1, only sulfur powder is added to the nutrient soil and retted for 20 days, and the seedling raising substrates are composed of adding 0, 10 g, 15 g, 20 g, 25 g, 30 g, and 35 g of sulfur powder to every 4 Kg of nutrient soil respectively. The remaining seedling raising conditions are the same as those in Example 1. The numbers of the artificial climate chamber simulation of cold snap in spring rice seedling raising experiment using the above seedling raising substrates and soil covering methods are respectively recorded as CK, S1.2, S1.3, S1.4, S1.5, S1.6, and S1.7.

[0057] Control test group 2: The second comparative test group provides a rice seedling raising method. The specific steps are different from those in Example 1 in that: in the second comparative test group, only urea and potassium dihydrogen phosphate are added to the nutrient soil and retted for 20 days. Each component of the seedling raising agent includes 1 g of urea + 1 g of potassium dihydrogen phosphate and is only used in the bottom soil, 0.5 g of urea + 0.5 g of potassium dihydrogen phosphate, 1 g of urea + 1 g of potassium dihydrogen phosphate, 1.5 g of urea + 1.5 g of potassium dihydrogen phosphate, 2 g of urea + 2 g of potassium dihydrogen phosphate. Then, one portion of the above seedling raising agent is added to every 4 Kg of nutrient soil to form the seedling raising substrate respectively. The remaining seedling raising conditions are the same as those in Example 1. The numbers of the artificial climate chamber simulation late spring cold snap seedling raising tests using the above seedling raising substrate and soil covering method are respectively recorded as DFCK, DF2.2, DF2.3, DF2.4, and DF2.5.

[0058] The specific operation of the artificial climate chamber simulation late spring cold snap seedling raising test is as follows: all the tests are completed in an RQS-10 artificial climate chamber (Ningbo Laifu Technology Co., Ltd.) to imitate the field climate. Before emergence, the set temperature is: 30 °C, and the relative humidity is 80%, which is conducive to uniform emergence and early full emergence. After emergence, the first stage (before the 2-leaf stage): 15 °C at night for 12 hours and 25 °C during the day for 12 hours. The second stage: 2 - 3 leaves, the weaning stage, 5 °C at night and 10 °C during the day; the third stage: about 3 leaves (imitating high temperature): 20 °C at night and 28 °C during the day. During this period, water is applied in a timely manner according to the soil temperature, and the water quality is tap water.

[0059] The rice variety is: For Taoyouxiangzhan, the seeding rate is 0.15 jin per tray (dry grain), and sowing is carried out after more than 80% of the seeds are germinated and the chest is broken.

[0060] Table 1 shows the physiological data of the rice seedlings in Examples 1 to 4 in the late spring cold snap seedling raising test

[0061]

[0062] Table 2 shows the physiological data of the rice seedlings in the first comparative test group in the late spring cold snap seedling raising test

[0063]

[0064] Table 3 shows the physiological data of the rice seedlings in the second comparative test group in the late spring cold snap seedling raising test

[0065]

[0066] From Table 1 to Table 3, and from Figures 1 to 3It can be seen that when both the topsoil and the subsoil adopt sulfur powder, urea and potassium dihydrogen phosphate, the seedlings cultivated have relatively strong ability to resist low-temperature persecution, with more developed roots, a larger root-shoot ratio, the lowest incidence rate, thicker leaves and older leaf ages. The present invention has an obvious promoting effect on the plant height, the growth of white roots and the leaf age of the seedlings, can significantly improve the stress resistance during the seedling growth period, and has a significant effect on cultivating strong seedlings.

[0067] Meanwhile, when the seedling-raising agent containing sulfur powder, urea and potassium dihydrogen phosphate is mixed with the nutrient soil, the ability of the seedlings to resist low-temperature persecution can be further improved through the retting step. This seedling-raising agent, the seedling-raising substrate and the rice seedling-raising method can improve the ability of the seedlings for machine transplanting with carpet seedlings in protected areas such as multi-span greenhouses, plastic greenhouses and plastic small arch greenhouses to resist low-temperature persecution, enabling the seedling raising under the early spring low-temperature environment to have the ability to resist the cold snap in spring.

[0068] Furthermore, the above tests show that the optimal ratio of the seedling-raising agent containing sulfur powder, urea and potassium dihydrogen phosphate is 25:0.5:0.5. When using and selling, 25 g of sulfur powder, 0.5 g of urea and 0.5 g of potassium dihydrogen phosphate are used as 1 portion of the seedling-raising agent, and after retting for 20 d according to the standard of adding 1 portion of the seedling-raising agent per 4 kg, it is used as the topsoil and the subsoil.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A rice seedling raising method, the specific steps include: First, weigh nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate according to the mass ratio of 4000:25:(0.5 - 2):(0.5 - 2) respectively. After mixing, control the water content to be 10% - 15% and conduct stuffiness for 10 - 25 days to obtain a seedling raising substrate; evenly cover a layer of the seedling raising substrate with a thickness of 2 cm - 2.5 cm in the seedling tray as the bottom soil, sow the pre-treated rice seeds on the bottom soil, and then evenly cover a layer of the seedling raising substrate with a thickness of 0.3 cm - 0.5 cm on the surface of the bottom soil as the covering soil. Then, conduct seedbed management according to the standard of protecting carpet seedlings; it is used to solve the low-temperature cold damage and damping-off caused by the late spring cold snap, and it is used to solve the physiological blight caused by physiological water loss due to the weak water absorption ability of the seedling roots and large transpiration consumption when the temperature rises after the late spring cold snap.

2. The rice seedling raising method according to claim 1, characterized in that, The nutrient soil is taken from vegetable garden soil, matured dryland soil, or paddy soil that has been winter-plowed and spring-puddled.

3. The rice seedling raising method according to claim 1 or 2, characterized in that, The steps of the stuffiness include piling up the mixed nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate at room temperature, covering with a film on the top, and then standing for 10 days - 25 days.

4. The rice seedling raising method according to claim 3, characterized in that, The time for stuffiness is 19 days - 21 days.

5. The rice seedling raising method according to claim 4, characterized in that, The steps of conducting seedbed management according to the standard of protecting carpet seedlings include: The needle-emergence stage: From sowing to the tip of the first leaf showing, during this period, mainly cultivate the seed roots. It is required that the temperature in the protected area does not exceed 32°C. When it exceeds 32°C, start ventilation; The green-emergence stage: From emergence to the full expansion of the first complete leaf, control the height of the first leaf sheath above the ground not to exceed 3 cm, and promote the growth of 5 new roots underground. The temperature in the protected area is controlled at 22°C - 25°C; The weaning stage: From the tip of the second leaf showing to the expansion of the third leaf, promote the growth of new roots underground, control the height of the seedlings above the ground, and control the temperature in the protected area at 20°C - 22°C. During this period, increase ventilation and harden the seedlings to reduce humidity; The pre-planting stage: Control water and squat the seedlings to strengthen the roots, making the seedlings in a state of hunger and thirst; after the seedlings have 3 leaves and 1 heart, conduct transplantation.

6. The rice seedling raising method according to claim 5, characterized in that, The steps of pre-treating rice seeds include: First, sun the seeds 5 days - 7 days before soaking. After soaking with the liquid medicine for 1 day, conduct seed disinfection. After rinsing the liquid medicine clean, transfer to warm water for soaking for 2 days - 3 days, and then conduct germination treatment. Among them, germination requires three stages: high-temperature chest-breaking, constant-temperature germination, and normal-temperature air-drying of buds. When breaking the chest at high temperature, the temperature is controlled at 38°C, and the time is 4 hours - 6 hours; when germinating at a constant temperature, the temperature is controlled at 25°C - 30°C, and the time is 18 hours - 20 hours.

7. A seedling-raising substrate, characterized in that, The seedling raising substrate is made by stuffing nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate at a water content of 10% - 15% for 10 days - 25 days. Among them, the mass ratio of nutrient soil, sulfur powder, urea, and potassium dihydrogen phosphate is 4000:25:(0.5 - 2):(0.5 - 2); the nutrient soil is taken from vegetable garden soil, matured dryland soil, or paddy soil that has been winter-plowed and spring-puddled.

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