CN109303058B

CN109303058B - Low-temperature-resistant regulating agent for rice seedlings and preparation method and application thereof

Info

Publication number: CN109303058B
Application number: CN201810757750.1A
Authority: CN
Inventors: 张桂莲; 蔡志欢; 唐文帮
Original assignee: Hunan Agricultural University
Current assignee: Hunan Agricultural University
Priority date: 2018-07-11
Filing date: 2018-07-11
Publication date: 2021-03-26
Anticipated expiration: 2038-07-11
Also published as: CN109303058A

Abstract

The invention discloses a low temperature resistance regulating agent for rice seedlings, which comprises uniconazole solution with the mass concentration of 19-21 mg/L and KH with the mass concentration of 5-7 g/L₂PO₄The composition comprises a solution, a salicylic acid solution with the mass concentration of 99-101 mg/L and a abscisic acid solution with the mass concentration of 9-11 mg/L, wherein the uniconazole solution and the KH solution₂PO₄The volume ratio of the solution, the salicylic acid solution and the abscisic acid solution is 1-3: 2-4: 0.5-1.5. Practice shows that the low temperature resistant regulating agent for rice seedlings can obviously reduce low temperature cold damage of rice seedlings in a seedling stage and improve the survival rate of the rice seedlings at low temperature by matching with a corresponding regulating method.

Description

Low-temperature-resistant regulating agent for rice seedlings and preparation method and application thereof

Technical Field

The invention belongs to the technical field of agricultural production, and particularly relates to a low temperature resistance regulating agent for rice seedlings, and a preparation method and application thereof.

Background

The rice is the main grain crop, and the sowing area of the rice all over the world is about 1.4 hundred million hm²Therein, 1500 ten thousand hm²The above rice crop area is threatened by low temperature. The cold damage of rice has become a worldwide problem, and the loss of rice caused by low temperature reaches 30-50 hundred million kg each year. The rice is also one of the main grain crops in China, the planting region is wide, the rice is planted from 53 degrees 27 'to 18 degrees 90' in north latitude, the seeding area, the total yield and the single yield of the rice are all in the top of the grain crops, and the rice occupies great importance in national economyThe essential position. But suffers from different degrees of low temperature freezing in almost all areas where rice is produced. The types of rice cold injury in China mainly include: cold damage in spring: 2. the 3 months are the sowing and seedling raising seasons of the early rice in south China, and at the moment, cold air in the north frequently meets warm and humid air flow moving on the sea in the south, so that rapid cooling or continuous low-temperature rainy weather is formed, and early rice seedling rot is easily caused. 3. In the 4 th month, the early rice is sowed and sprout cultivation season in the middle and lower reaches of Yangtze river, and the early rice is rotten due to frequent alternation of cold and warm air and low-temperature rainy weather. Cold damage in summer: due to the fact that the latitude is high, the continental monsoon climate is obvious, the weather and climate conditions of each year are changed greatly, the heat condition is not stable, low-temperature weather can be met in the rice growth period of some years, and large-area yield reduction of rice is caused by insufficient heat. Cold damage in autumn: before and after the cold dew falls in the autumn every year, the critical period of ear sprouting and flowering of late rice in south China and the middle and lower reaches of Yangtze river is positive, and at the time, if the late rice is damaged by low temperature, the rice can be crushed to cause empty shells and grains, so that the yield is reduced. The middle and lower reaches of Yangtze river in China belong to subtropical monsoon climate, and the resources of heat and moisture are rich, thereby being beneficial to the production of double cropping rice. However, due to the influence of the season wind, the seedlings are often attacked by cold and damp in spring, so that the seedling rot and death are caused by spring coldness of different degrees in some years. After the seedling stage is subjected to low-temperature cold damage, the leaf color of the whole plant turns yellow, yellow leaves are generated at the lower part of the plant, some leaves are brown, and part of the leaves are white or yellow to yellowish white horizontal stripes, which are commonly called as 'yellow joints' or 'white joints', even seedlings are rotten and die; the number of glumes is reduced due to cold damage in the booting stage, and the development of young ears is inhibited; the cold injury of the heading populus at the flowering period causes poor anther cracking, reduces the pollination number of stigma, influences the activity of pollen, causes sterility, namely, fertilization obstacle occurs, and causes the fructification rate to be reduced; the elongation of cold damage grains in the mature period becomes slow, when the cold damage grains are frosted, the mature process stops, the thousand grain weight is reduced, and the large-area yield reduction of the rice is caused. Therefore, the improvement of the low-temperature resistance of the rice becomes a hot spot of the current rice research, and has profound significance for promoting the continuous and stable development of the rice.

The cold injury can be suffered in all stages of the growth and development of the rice, the seedling stage is one of the most vulnerable stages of the rice to the cold injury at low temperature, and the seedling stage is closely related to the cold resistance of the booting stage, the flowering stage and the mature stage. Seedling withering is one of the main types of low temperature harm, often because after long-term low temperature, soil temperature is too low, leads to the root system can't absorb sufficient moisture to satisfy the demand of overground part, causes the plant to appear withering, if after long-term low temperature, the temperature rises too fast, can show the emergence of this phenomenon with higher speed. The low temperature in the seedling stage causes the rice seedlings to grow slowly, leaves to discolor or be damaged, leaves look wet, and like being soaked in water for a long time, when roots are affected by the low temperature, the plants may wither or wither, the cell membrane permeability is increased, severe water shortage and other symptoms occur, and the seedlings die in severe cases.

The research on the reduction of the low-temperature cold damage of the rice seedling stage is widely researched domestically and abroad in the aspects of screening of low-temperature resistant varieties of the rice, regulating and controlling of fertilizer and water in the rice field, mulching of the rice, spraying of foliar fertilizer, plant growth regulator and the like. In the screening of rice low-temperature resistant varieties, the screened low-temperature resistant varieties often have obvious regional differences and even have obvious differences among years. In production, no rice variety can be widely used for low-temperature environment production at home and abroad. The fertilizer and water regulation and control are to reduce the low-temperature cold damage of the rice by reasonable fertilization and water irrigation technologies, wherein the irrigation is an effective way, a method of discharging water at night is generally adopted, the water irrigation and the heat preservation are carried out at nights, a large amount of workload is increased for large-area rice cultivation, the method is unrealistic for northern areas of China with increasingly severe water resources and some southern arid areas or some seasonal water shortage areas, meanwhile, the water discharge at night is easy to reduce the soil fertility of the rice field to be unfavorable for the growth of the rice, and the utilization value is very limited. The mulching film is adopted for covering, which is beneficial to the low-temperature defense in a short period of seedling raising, but cannot resist the low-temperature toxicity for a long time, for example, the large-area covering film is not practical when the low temperature comes in the early rice direct seeding or tillering and grouting periods, and meanwhile, the mulching film can seriously affect the photosynthesis of the rice, seriously damage the growth of the rice and influence the rice yield. The foliage spraying of the plant growth hormone can improve the low-temperature tolerance of the rice, but has the problem of high cost, for example, ABA is a single cold-resistant agent with the best cold-resistant effect at present, but the cost is too high, and in addition, the plant growth hormone can regulate and control the physiological growth of other aspects of the rice, such as inhibiting cell division, promoting prematurity and the like. Therefore, no universal, effective and applicable method is practically applied to reducing the low-temperature cold damage of rice in the seedling stage.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a low-temperature resistant regulating agent for rice seedlings, which can reduce low-temperature cold damage of the rice seedlings at the seedling stage and is low in cost, and also provides a preparation method and specific application of the low-temperature resistant regulating agent for the rice seedlings.

In order to solve the technical problems, the invention adopts the following technical scheme:

a low-temperature-resistant regulating agent for rice seedlings comprises a uniconazole solution with the mass concentration of 19-21 mg/L and KH with the mass concentration of 5-7 g/L₂PO₄The composition comprises a solution, a salicylic acid solution with the mass concentration of 99-101 mg/L and a abscisic acid solution with the mass concentration of 9-11 mg/L, wherein the uniconazole solution and the KH solution₂PO₄The volume ratio of the solution, the salicylic acid solution and the abscisic acid solution is 1-3: 2-4: 0.5-1.5.

Abscisic acid is a well-recognized and good cold-resistant agent, but is not practical in actual large-area production due to high price. Some traditional technologies believe that for some crops, the effects of salicylic acid and abscisic acid (ABA) are crossed, the synthesis of the ABA has two paths, namely a direct path and an indirect path, the latter needs Lipoxygenase (LOX) to participate, and the salicylic acid can inhibit the activity of the lipoxygenase and regulate the synthesis of the ABA by regulating the direct synthesis path of the ABA, so that the salicylic acid can improve the cold resistance of some crops through ABA induction. The research of the invention shows that for a special object of rice seedlings, the low temperature resistance effect of the combination of the abscisic acid and the salicylic acid on the rice seedlings is rather inferior to the effect of applying the abscisic acid alone, but the effect is superior to the effect of applying the salicylic acid alone, probably because the abscisic acid is only used in a ratio of 1:1, and if the ratio of the abscisic acid is increased, the effect is better, but the cost is greatly increased. This also indicates that the binary formulation ratio may have some inhibitory effect on the cold resistance of a particular subject.

Further studies of the invention show that uniconazole and KH₂PO₄The low temperature resistance regulating and controlling effect of the mixed regulating and controlling agent on rice seedlings can be obviously improved by compounding the mixed regulating and controlling agent with salicylic acid and abscisic acid. Practice proves that the low-temperature resistant regulation and control effect on rice seedlings is very obvious, and a remarkable synergistic induction effect is shown. Specifically, the uniconazole has the general effects of inhibiting cell elongation, shortening internodes and cultivating strong and short seedlings on crops; the potassium dihydrogen phosphate belongs to a high-efficiency phosphorus-potassium compound fertilizer, can provide P element and K element for seedling growth, can also improve the chlorophyll content, enhance photosynthesis and effectively promote the growth and development of root systems. In conventional studies, the low temperature induction resistant effects of the two on crops are not significant. The research of the invention finds that KH is₂PO₄Shows unexpected low temperature control effect on a special object of rice seedlings, and has uniconazole and KH₂PO₄The low-temperature resistant regulating and controlling effect of the mixed regulating and controlling agent on rice seedlings can be obviously improved by compounding the mixed regulating and controlling agent with salicylic acid and abscisic acid according to the proportion of the invention. The test result shows that the seedling survival rate of the rice seedlings regulated and controlled by the quaternary compound agent is 82.1 percent, the seedling survival rate of the rice seedlings regulated and controlled by the salicylic acid and ABA binary compound agent is 52.56 percent, the difference between the seedling survival rates is 29.54 percent, and the difference is obvious. The synergistic cold-resistant regulating effect of the uniconazole and the monopotassium phosphate, the salicylic acid and the ABA is probably a special object of the rice seedling, the activity of the seedling protective enzyme is obviously improved, the malonaldehyde content and the relative conductivity are reduced, and the structure and the function of a cell membrane are relatively stable, so that the synergistic cold-resistant regulating effect is obviously superior to the regulating effect of the salicylic acid and ABA binary compound agent.

As a general inventive concept, the invention also provides a preparation method of the low temperature resistance regulator for the rice seedlings, and before use, uniconazole solution with the mass concentration of 19-21 mg/L and KH with the mass concentration of 5-7 g/L are mixed₂PO₄The solution, the salicylic acid solution with the mass concentration of 99-101 mg/L and the abscisic acid solution with the mass concentration of 9-11 mg/L are prepared according to the volume ratio of 1-3: 2-4: 0.5-1.5 to form a mixed solution。

The practice proves that the low temperature resistance regulating agent for the rice seedlings has better effect when being prepared on site. Before blending, the abscisic acid solution is stored at low temperature, and the uniconazole solution and the salicylic acid solution are stored in a dark place.

In the above preparation method, preferably, the uniconazole solution and the KH₂PO₄The volume ratio of the solution, the salicylic acid solution and the abscisic acid solution is 2:3: 1.

As a general inventive concept, the invention also provides an application of the low temperature resistance regulator for the rice seedlings or the low temperature resistance regulator for the rice seedlings prepared by the preparation method in reducing the low temperature cold damage of the rice seedling stage.

In the above application, preferably, the rice seedlings are direct-seeding rice seedlings, and the application comprises the following steps:

and spraying the low-temperature resistant regulating agent on the rice seedlings in the two-leaf one-heart period of the rice seedlings.

In the above application, preferably, the rice seedlings are rice seedlings raised on a seedling tray or rice seedlings raised in a field, and the application comprises the following steps:

and spraying the low-temperature-resistant regulating agent to the rice seedlings in the 2-4 leaf stage of the rice seedlings.

The above application, preferably, the spraying operation is: spraying the fertilizer once every day until the whole rice seedling plant is wet; continuously spraying for 3-5 days.

The above application, preferably, is continuous spraying for 3 days.

The above application, preferably, further comprises the following steps:

in the rice seedling stage, 1-3 days before low temperature comes, the rice seedling low temperature resistant regulating agent is adopted to carry out additional spraying on rice seedlings; the low temperature is low-temperature weather with the natural environment temperature of 6-10 ℃ and the time duration range of 3-5 days.

In the above application, preferably, the additional spraying operation is: spraying the fertilizer once every day until the whole rice seedling plant is wet; continuously spraying for 2-3 days.

Compared with the prior art, the invention has the advantages that:

1. the low-temperature-resistant regulating agent for the rice seedlings can obviously improve the activity of protective enzyme of the rice seedlings, reduce the content of malonaldehyde and relative conductivity, and maintain the structure and function of cell membranes relatively stable; the growth of root systems can be promoted, the activity of the root systems of the seedlings can be improved, and the normal supply of water on the overground parts of the seedlings can be maintained; in addition, the chlorophyll content of the seedlings can be increased, and the photosynthesis is enhanced, so that the survival rate of the rice seedlings at low temperature is increased, the harm of the low temperature to the rice seedlings is reduced, and the effect of improving the low temperature resistance of the rice seedlings is achieved.

2. Practice shows that the low-temperature resistant regulating agent for the rice seedlings is sprayed to the direct-sowing rice seedlings in the two-leaf one-heart period of the rice seedlings, so that the harm of low temperature to the rice seedlings in the seedling period can be reduced to the greatest extent; for rice seedling raised on a seedling tray or rice seedling raised in a field, the low-temperature-resistant regulating agent for rice seedlings is sprayed in the 2-4 leaf stage of the rice seedlings, so that the damage of low temperature in the seedling stage to the rice seedlings can be reduced to the greatest extent. Meanwhile, the low temperature resistance regulating agent for the rice seedlings is applied at low temperature, so that the harm of low temperature in the seedling stage to the rice seedlings can be further reduced.

Detailed Description

The invention is further described below with reference to specific preferred embodiments, without thereby limiting the scope of protection of the invention.

Rice seedling raising

Soaking Xiangzaixian No. 45 seeds in clear water for 12 hours, then soaking the seeds in 300 times of strong chlorine solution for 12 hours, washing the seeds clean by tap water, continuously soaking the seeds for 2 days, accelerating germination after the seed soaking, sowing the seeds after the accelerating germination in a culture box in the soil of a paddy field, sowing 100 seeds in each box, repeating the steps for four times, and culturing the seeds in a light culture box (25 ℃, the light intensity of 12000lx and the humidity of 70-80%) until the two-leaf one-heart period.

Selection of dosage and formulation of regulating agent

(1) Single dose screening

Soaking seeds of Xiangzaixian No. 45 seeds for germination, sowing the seeds in a culture box of soil of a paddy field, sowing 100 seeds in each box for four times, and when the seeds are cultured in a lighting culture box (25 ℃, the light intensity is 12000lx and the humidity is 70% -80%) to a two-leaf one-heart period, respectively spraying calcium chloride, uniconazole, phosphate fertilizer, 6-BA, salicylic acid, abscisic acid and proline solution (the specific concentration is shown in the table 1) with different concentrations on rice seedlings by using a small-sized spray can for 3 times each day, then moving the rice seedlings into the lighting culture box for low-temperature treatment (8:00-17:00, 10 ℃, 17:00-8:00 and 8 ℃) for 5 days, and meanwhile, spraying distilled water as a Contrast (CK), wherein the lighting of the lighting culture box is set to be 12h, the light intensity is 12000lx and the relative humidity is 70% -80%. After treatment for 5 days, the temperature of the light incubator was adjusted to 25 ℃ to recover the growth, and after 5 days, the survival rate was recorded, and the results are shown in Table 1.

TABLE 1 Single agent screening

Note: the data in the table are the average of 4 replicates. The lower case letters a, b, c, d, etc. following the data in the table are statistically used to indicate whether the inter-treatment differences are significant, different lower case letters indicate that the inter-treatment differences are significant at a level of 5%, and the same letters indicate that the inter-treatment differences are not significant at a level of 5%, which is a commonly used representation method in natural science research.

As can be seen from Table 1, the two reagents with the best overall effect are abscisic acid and potassium dihydrogen phosphate solution respectively, and the concentration treatment of the two reagents can improve the survival rate of the early indica No. 45 seedlings by more than 30 percent after the seedlings are stressed at low temperature; the survival rate of seedlings after low-temperature stress can be obviously increased by calcium chloride, uniconazole and salicylic acid solution in other reagents. The survival rate of the 6-BA and proline solution is not obviously improved under the low-temperature stress to the Xiang early indica No. 45 seedlings in the test concentration. Now, 0.01mol/L calcium chloride solution, 20mg/L uniconazole solution and 6g/L KH solution are selected₂PO₄The solution, 100mg/L salicylic acid solution and 10mg/L abscisic acid solution are subjected to the next step of screening the mixed regulating agent.

(2) Screening of mixture

Soaking seeds of the early-maturing indica No. 45 Xiang for accelerating germination, sowing the seeds in a culture box in the soil of a paddy field,sowing 100 seeds in each box, repeating for four times, culturing in a light incubator (25 deg.C, light intensity 12000lx, humidity 70% -80%) until two leaves and one heart stage, adding 0.01mol/L calcium chloride solution, 20mg/L uniconazole solution, and 6g/L KH₂PO₄The method comprises the steps of preparing different mixing agents according to a certain volume ratio from 2, 3, 4 and 5 solutions of a solution, 100mg/L salicylic acid solution and 10mg/L abscisic acid solution (A, B, C, D, E is used for replacing the solutions respectively), uniformly spraying the mixed solution with different concentrations on rice seedlings by using a small spraying pot for 3 times each day, then transferring the rice seedlings into an illumination incubator for low-temperature treatment (8:00-17:00, 10 ℃, 17:00-8:00 and 8 ℃) for 5 days, and simultaneously spraying distilled water as a Control (CK), wherein the illumination of the illumination incubator is set to be 12 hours, the light intensity is 12000lx, and the relative humidity is 70-80%. After treatment for 5 days, the temperature of the light incubator was adjusted to 25 ℃ to recover the growth, and after 5 days, the survival rate was recorded, and the results are shown in Table 2.

TABLE 2 combination screening

Reagent collocation	Ratio of	Survival Rate (%)	Root system activity (mu g.g)^-1.h^-1)
				BCD	2:3:1	60.73bc	300.12bc
BCD	1:3:1	64.88b	324.56b
				BCE	2:1:1	62.18bc	312.34bc
BCDE	2:3:1:1	82.10a	432.21a
				BCDE	3:1:1:1	59.33bc	295.87bc
BCD	3:1:1	56.26bcd	282.12bcd
				BC	1:1	55.49bcd	276.45bcd
ABCDE	1:2:3:1:1	54.54cd	270.12cd
				DE	1:1	52.56cd	258.34d
CDE	2:1:1	53.21cd	265.34cd
				ABCD	1:1:3:1	48.60d	255.34d
Distilled water (CK)		12.45e	189.78e

Note: the lower case letters a, b, c, d, etc. following the data in table 2 are statistically used to indicate whether the inter-treatment differences were significant, different lower case letters indicate that the inter-treatment differences were significant at a level of 5%, and the same letters indicate that the inter-treatment differences were not significant at a level of 5%, which is a commonly used representation in natural science research.

As can be seen from Table 2, the 10 mixed solutions listed in the table can improve the survival rate of the early indica No. 45 rice seedlings by more than 30% after the seedlings suffer from low temperature stress in the two-leaf one-heart stage, and the significant difference is achieved. Among them, BCDE solution (i.e. 20mg/L uniconazole solution, 6g/L KH solution) is the best effect₂PO₄Solution, 100mg/L salicylic acid solution and 10mg/L abscisic acid solution) according to the ratio of 2:3:1:1, compared with the spraying of distilled water (CK), the rate of the seedlings is improved by 69.65%, compared with the single-agent spraying and other ratios of the mixed solution, the rate of the seedlings is improved greatly, and the effect is good.

Selection of time and days for spraying of control agent

According to the above results, in one-leaf one-heart period, two-leaf one-heart period, three-leaf one-heart periodFour groups of rice seedlings in 4-leaf one-heart stage were treated with a control solution (20mg/L uniconazole solution, 6g/L KH)₂PO₄Mixed solution prepared by the solution, 100mg/L salicylic acid solution and 10mg/L abscisic acid solution according to the proportion of 2:3:1: 1) is uniformly sprayed on rice plants, the spraying amount is based on that the whole plants are completely wetted by the solution, the spraying days of each group at different stages are set as 1 day, 2 days, 3 days and 4 days, then the rice materials are moved into a light culture box to be subjected to artificial simulated low-temperature treatment (8:00-17:00, 10 ℃, 17:00-8:00 and 8 ℃), and the materials are moved outdoors to continue to grow for 5 days after continuous treatment for 5 days. And (5) after the treatment is finished, measuring the root activity and investigating the survival rate when the seedlings are recovered for 5 days. The result shows that the root activity and the survival rate of the seedlings continuously sprayed for 3 days in the two-leaf one-heart period are improved to the maximum extent and the best effect compared with the control treatment (clear water), and the root activity of the seedlings is improved by 242.43 mu g.g^-1.h^-1Compared with the spraying of distilled water (CK), the survival rate is improved by 69.65%.

Artificially simulated low temperature and conditioning agent treatment

(1) Influence of different proportions of mixed regulating and controlling agent on survival rate of rice seedlings

Soaking seeds of Xiangzaixiang No. 45, germinating, sowing in culture box of rice field, sowing 100 seeds in each box, repeating for four times, culturing in illumination culture box (25 deg.C, light intensity 12000lx, humidity 70% -80%) until two leaves and one heart stage, adding uniconazole solution 20mg/L, KH 6g/L₂PO₄Three regulating agent solutions prepared by the solution, the salicylic acid solution of 100mg/L and the abscisic acid solution of 10mg/L according to the proportion of 1:2:0.5:0.5, 2:3:1:1, 3:4:1.5:1.5 are uniformly sprayed on three groups of rice plants, the spraying amount is based on the fact that the whole plant is completely wetted by the solution, the three regulating agent solutions are continuously sprayed for 3 days from the 2-leaf first-heart stage, and the solution sprayed with clear water is used as a Control (CK). Then the rice material is moved into a light incubator to be processed at a low temperature (8:00-17:00, 10 ℃, 17:00-8:00, 8 ℃) by artificial simulation, and the material is moved to the outdoor (25 ℃) to continue to grow for 5 days after being continuously processed for 5 days. The mortality rate was examined 3d after recovery, and the results are shown in Table 3.

TABLE 3 influence of different ratios of mixed control agent spraying on the survival rate of rice seedlings at low temperature

Reagent collocation	Ratio of	Survival Rate (%)
			BCDE	1:2:0.5:0.5	81.24a
BCDE	2:3:1:1	82.10a
			BCDE	3:4:1.5:1.5	82.00a
Distilled water (CK)		12.45b

Note: BCDE represents 20mg/L uniconazole solution and 6g/L KH respectively₂PO₄The solution, salicylic acid solution of 100mg/L and abscisic acid solution of 10 mg/L.

The lower case letters a, b following the data in table 3 are statistically used to indicate whether the inter-treatment difference is significant, different lower case letters indicate that the inter-treatment difference is significant at a level of 5%, and the same letter indicates that the inter-treatment difference is not significant at a level of 5%, which is a commonly used representation method in natural science research. As can be seen from table 3, the difference between the 3 mixture ratios of the mixed control agent and distilled water (CK) reaches a significant level of 5%, and the difference between the 3 mixture ratios of the mixed control agent is not significant.

As can be seen from Table 3, the effect of spraying the mixed regulating agent in 3 proportions on the survival rate of rice seedlings is not obviously different, but is obviously improved compared with the control.

(2) Influence of spraying mixed regulating agent on physiological characteristics of rice seedlings under low-temperature stress

Soaking seeds of Xiangzaixiang No. 45, germinating, sowing in culture box of rice field, sowing 100 seeds in each box, repeating for four times, culturing in illumination culture box (25 deg.C, light intensity 12000lx, humidity 70% -80%) until two leaves and one heart stage, adding uniconazole solution 20mg/L, KH 6g/L₂PO₄The solution, the salicylic acid solution of 100mg/L and the abscisic acid solution of 10mg/L are prepared into a regulating agent solution according to the proportion of 2:3:1:1, the regulating agent solution is uniformly sprayed on rice plants, the spraying amount is based on the fact that the whole plants are completely wetted by the solution, the regulating agent solution is continuously sprayed for 3 days from the 2-leaf first-heart stage, and the clear water is sprayed as a Control (CK). Then the rice material is moved into a light incubator to be processed at a low temperature (8:00-17:00, 10 ℃, 17:00-8:00, 8 ℃) by artificial simulation, and the material is moved to the outdoor (25 ℃) to continue to grow for 5 days after being continuously processed for 5 days. Samples were taken before the low-temperature treatment, at the 5 th day after the low-temperature treatment and at the 3 rd day after the recovery to measure the fresh weight of each hundred plants, the dry weight of each hundred plants, the Malondialdehyde (MDA) content, the relative conductivity, the SOD activity, the POD activity and the root activity, and the survival rate was investigated at the 3d day after the recovery, with the results shown in Table 4.

TABLE 4 influence of spraying mixed control agent on physiological characteristics of rice seedlings under low temperature stress

Note: the lower case letters a, b following the data in table 4 are statistically used to indicate whether the inter-treatment difference is significant, different lower case letters indicate that the inter-treatment difference is significant at a level of 5%, and the same letter indicates that the inter-treatment difference is not significant at a level of 5%, which is a commonly used representation method in natural science research.

As can be seen from Table 4, compared with the control, the spraying of the mixed regulator can increase the fresh weight and dry weight of the overground part of the seedling, after the low-temperature treatment for 5 days, the fresh weight and dry weight of the overground part of Xiang early indica No. 45 are respectively increased by 34.45% and 4.20% compared with the control, and after the treatment is finished and the overground part is restored for 3 days, the fresh weight and the dry weight are respectively increased by 52.84% and 4.24% compared with the control; the cold stress increases the malondialdehyde content and the relative conductivity in the seedling leaves, compared with the control, the spraying of the mixed regulating agent obviously reduces the malondialdehyde content and the relative conductivity of the leaves, the malondialdehyde content and the relative conductivity of the leaves treated by the control and the spraying of the mixed regulating agent before treatment are not obviously different, but the malondialdehyde content and the relative conductivity of the 5d treated leaves are respectively reduced by 16.95 percent and 30.01 percent compared with the control, and the malondialdehyde content and the relative conductivity of the 3d recovered leaves are respectively reduced by 45.10 percent and 57.18 percent compared with the control; compared with the control, the SOD activity and POD activity of the leaves sprayed with the mixed regulating agent under low-temperature stress are increased, the SOD activity and POD activity of the mixed regulating agent sprayed at the 5 th day are respectively increased by 23.64 percent and 44.58 percent compared with the control, and the SOD activity and POD activity of the mixed regulating agent sprayed at the 3 rd day are respectively increased by 49.72 percent and 67.66 percent compared with the control; compared with the control, the chlorophyll content of the seedlings sprayed with the mixed regulating agent on the 5 th day of low-temperature stress and the 3 rd recovery day is respectively increased by 30.79 percent and 33.01 percent compared with the control. Compared with the control, the root system activity of the seedlings sprayed with the mixed regulating agent on the 5 th day of low-temperature stress and the 3 rd recovery day is respectively increased by 30.84 percent and 82.52 percent compared with the control. The survival rate of the seedlings is investigated on the 3 rd day after recovery, and the result shows that the survival rate of the control seedlings under low-temperature stress is 12.45 percent, while the survival rate of the seedlings sprayed with the mixed regulating agent is 82.1 percent, which is 69.65 percent higher than that of the control.

As can be seen, under the condition of low temperature, the uniconazole solution containing 20mg/L and KH containing 6g/L are sprayed for 3 days continuously from the two-leaf one-heart stage of the rice seedlings₂PO₄The regulator solution is prepared from the solution, 100mg/L salicylic acid solution and 10mg/L abscisic acid solution according to the proportion of 2:3:1:1, so that the content and the relative conductivity of malondialdehyde of the leaves are reduced, the activity of the leaf protection enzyme, the content of chlorophyll and the activity of root systems are increased, the survival rate of seedlings is improved, and the harm of low temperature to rice seedlings is reduced.

In advance ofIn the row test, for example, for seedling raising on a seedling tray and seedling raising on a field, 2-4 leaves grow on seedlings, and the seedlings are sprayed and simultaneously contain 20mg/L uniconazole solution and 6g/L KH₂PO₄Preparing the solution, 100mg/L salicylic acid solution and 10mg/L abscisic acid solution according to the proportion of 2:3:1:1 to obtain a regulator solution for 3 times; according to the weather forecast, spraying uniconazole solution containing 20mg/L and KH solution containing 6g/L for 3 consecutive days before low temperature comes₂PO₄The regulator solution prepared by the solution, the salicylic acid solution of 100mg/L and the abscisic acid solution of 10mg/L according to the proportion of 2:3:1:1 is used for 3 times, and finally the effect of improving the low-temperature resistance of the rice seedlings can be achieved.

The above description is only for the preferred embodiment of the present application and should not be taken as limiting the present application in any way, and although the present application has been disclosed in the preferred embodiment, it is not intended to limit the present application, and those skilled in the art should understand that they can make various changes and modifications within the technical scope of the present application without departing from the scope of the present application, and therefore all the changes and modifications can be made within the technical scope of the present application.

Claims

1. The low-temperature-resistant regulating agent for the rice seedlings is characterized by comprising 19-21 mg/L uniconazole solution and 5-7 g/L KH₂PO₄The solution, salicylic acid solution with the mass concentration of 99-101 mg/L and abscisic acid solution with the mass concentration of 9-11 mg/L;

the uniconazole solution and KH₂PO₄The volume ratio of the solution, the salicylic acid solution and the abscisic acid solution is 1-3: 2-4: 0.5-1.5.

2. The method for preparing the low temperature resistant controlling agent for rice seedlings according to claim 1, wherein before use, the uniconazole solution with the mass concentration of 19-21 mg/L and the KH solution with the mass concentration of 5-7 g/L are mixed₂PO₄The volume ratio of the solution, the salicylic acid solution with the mass concentration of 99-101 mg/L and the abscisic acid solution with the mass concentration of 9-11 mg/L is 1-3: 2-4: 0.5-1.5: 0.5-1.5 to form a mixed solution.

3. The process according to claim 2, wherein the uniconazole solution, KH₂PO₄The volume ratio of the solution, the salicylic acid solution and the abscisic acid solution is 2:3: 1.

4. The application of the low temperature resistance regulator for the rice seedlings according to claim 1 or the low temperature resistance regulator for the rice seedlings prepared by the preparation method according to any one of claims 2 to 3 in reducing low temperature cold damage of the rice seedlings.

5. The use according to claim 4, wherein the rice seedlings are direct-seeded rice seedlings, comprising the steps of:

6. The use according to claim 4, wherein the rice seedlings are rice seedlings raised on a seedling tray or rice seedlings raised in a field, the use comprising the steps of:

7. Use according to claim 5 or 6, wherein spraying is specifically operative to: spraying the fertilizer once every day until the whole rice seedling plant is wet; continuously spraying for 3-5 days.

8. Use according to claim 7, characterized in that spraying is continued for 3 days.

9. The use according to claim 7, further comprising the steps of:

10. The use of claim 9, wherein the additional spray application is operative to: spraying the fertilizer once every day until the whole rice seedling plant is wet; continuously spraying for 2-3 days.