Method for reducing rice yield loss in alkaline soil

Abstract

The invention relates to a method for reducing rice yield loss in alkaline soil. Active gibberellin is applied in vitro to rice in the alkaline soil. Compared with the prior art, the application finds that the survival rate of rice seedlings can be increased and the alkali resistance and heat resistance can be improved by applying a proper amount of active gibberellin (GA3) in vitro in the rice seedling stage under alkali and heat stress conditions. Researches find that when rice is planted on alkaline soil, the loss of the rice yield caused by alkali stress can be reduced and the stability of the rice yield can be maintained by applying gibberellin in vitro. The gibberellin (GA3) is widely applied to hybrid rice seed production and is basically non-toxic, and the concentration of the gibberellin applied in the method is low, so that the method is low in cost and easy to use, and has wide popularization and application value in crop production. The in-vitro application of gibberellin can make up for the reduction of the grain number per spike, plant height and other characters of the rice planted in alkaline soil, improve the alkali resistance of the rice and reduce the yield loss caused by alkali stress.

Description

Technical Field

[0001] The invention belongs to the technical field of agriculture, and in particular relates to a method for reducing rice yield loss in alkaline soil. Background Art

[0002] In nature, plants grow in a fixed growth environment and have evolved a set of mechanisms to perceive and respond to changing natural environmental conditions in order to meet their own growth and development. In this process, gibberellins play a key role. Many studies have shown that changes in the level of active gibberellins are beneficial to the survival of plants under a variety of environmental stresses, including cold, salinity, and drought. Studies have reported that increased biosynthesis of gibberellins and enhanced signal transduction promote the enhancement of plant escape responses to flooding. By changing the level of biologically active gibberellins and signal transduction, plants can coordinate growth and stress tolerance so that they can better survive and reproduce under adverse conditions.

[0003] Gibberellins not only regulate rice plant height, panicle length, spikelet number and growth metabolism, but also regulate rice's response to abiotic stress. The green gene SD1 (MUS number LOC_Os01g66100) encodes GA20 oxidase, which increases the content of bioactive gibberellins, leading to the degradation of DELLA proteins. DELLA proteins interact with multiple types of proteins, enabling gibberellins to regulate multiple traits of plants. Gibberellins not only regulate rice yield traits, but also regulate rice's response to adverse stress.

[0004] In addition, soil salinization and high temperature stress pose a threat to food. Therefore, it is urgent to develop new green rice varieties that are resistant to alkali and heat and have high yields to meet the needs of future population growth and climate change.

[0005] Gibberellic acid (GAs) are cyclic diterpenoid plant hormones that stimulate the growth of most organs and promote developmental stage transitions by enhancing cell division and promoting cell elongation. Their effects run throughout the life cycle of plants, including seed germination, stem elongation, leaf expansion, flower and fruit development. In the past few decades, green cultivars (GRVs) have been widely cultivated worldwide because their semi-dwarf plant structure provides lodging resistance under high nitrogen fertilizer supply and reduces yield losses due to lodging. The rice Semi-Dwarf1 (SD1) gene encodes gibberellin (GA) 20 oxidase, a gibberellin biosynthetic enzyme.

[0006] When the partially functional sd1 allele encodes a defective GA20 oxidase, resulting in a decrease in the concentration of bioactive gibberellins, it prevents the proteasomal degradation of SLR1 (DELLA protein in rice) by the gibberellin receptor GID1. However, the mechanism of how gibberellin signals regulate alkaline and heat stress is still unclear, and the relationship between rice green genes and rice tolerance to alkaline and heat stress is also unknown.

[0007] Chinese patent CN106034523A discloses an underground cave irrigation method that can enhance the salt-alkali resistance of plants and its application in the cultivation of Lythrum saline, including digging underground caves and soaking. In the soaking step, sorghum stalks are soaked in a nutrient solution; water and nutrients are mixed in a certain volume ratio to prepare a nutrient solution, and the nutrients include the following components: organic acid, nitrogen, phosphorus and potassium compound fertilizer, medium element fertilizer, trace element fertilizer, garlic extract, zhongshengmycin, madder, gibberellin, serine, fermented duck manure liquid, amylase, sodium naphthylacetate, fulvic acid, fucose, chlorogenic acid, and tangerine peel glycoside. This scheme uses irrigation to enhance the salt-alkali resistance of plants, which is achieved by adding a preparation mixed with various compound components into the nutrient solution. In this scheme, gibberellin is not the main component and needs to work together with other components. In addition, the scheme emphasizes underground cave irrigation. Summary of the invention

[0008] Since there is a lack of methods for reducing rice yield loss in alkaline soil in the prior art, the present invention provides a method for reducing rice yield loss in alkaline soil.

[0009] The purpose of the present invention can be achieved by the following technical solutions:

[0010] The invention provides a method for reducing rice yield loss in alkaline soil. Active gibberellin is applied in vitro to rice in alkaline soil at seedling stage or maturity stage.

[0011] In one embodiment of the present invention, at the seedling stage, the concentration of active gibberellin applied in vitro to rice in alkaline soil is 0.001-10 μM, preferably 0.1 μM.

[0012] In one embodiment of the present invention, the active gibberellin is gibberellin GA3.

[0013] In one embodiment of the present invention, the concentration of active gibberellins applied in vitro to rice in alkaline soil at maturity is 1 μM.

[0014] In one embodiment of the present invention, active gibberellins are applied in vitro to rice plants grown in alkaline soil under a high temperature environment at the seedling stage or the mature stage.

[0015] In one embodiment of the present invention, the active gibberellin is applied by spraying a liquid solution of the active gibberellin on the stems.

[0016] In one embodiment of the present invention, the active gibberellin is applied by spraying once a week.

[0017] In one embodiment of the present invention, active gibberellins are applied in vitro to rice in alkaline soil at the seedling stage or maturity stage to increase the number of grains per rice panicle, improve the alkali resistance of rice, and reduce the yield loss caused by alkaline stress.

[0018] In one embodiment of the present invention, the rice is selected from two representative rice varieties: Longtepu (indica rice variety) and Songxianggengdao (japonica rice variety).

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] 1. This study found that applying an appropriate amount of active gibberellin (GA3) to rice seedlings in vitro under alkali and heat stress conditions can increase the survival rate of rice seedlings and improve alkali and heat resistance.

[0021] 2. The present application has found that when rice is planted on alkaline soil, the loss of rice yield caused by alkaline stress can be reduced and the stability of rice yield can be maintained by applying gibberellins in vitro. Since gibberellins (GA3) (also referred to as gibberellins (920)) have been widely used in hybrid rice seed production, they are basically non-toxic, and the concentration of gibberellins applied in the present invention is low, and gibberellins (920) itself is cheap. Therefore, the method is low in cost, easy to use, and has wide application value in crop production.

[0022] 3. The application of gibberellins in vitro can compensate for the reduction in the number of grains per ear and plant height of rice grown in alkaline soil, improve the alkali resistance of rice, and reduce the yield loss caused by alkaline stress.

[0023] 4. The present application scheme uses gibberellin as the only active ingredient, and for the first time proves that a single active gibberellin is the key to regulating alkali and heat stress tolerance, which was previously unknown. Moreover, the present application first discovered that direct in vitro application of a single active gibberellin GA3 can significantly increase alkali stress tolerance. The present application found through scientific basic research and experimental verification that a single application of low-concentration active gibberellin (GA3) in vitro can simultaneously improve the agronomic traits of rice alkali resistance and high temperature resistance.

[0024] 5. The present study found that the concentration of a single active gibberellin (GA3) applied in vitro cannot be too high or too low (both high and low concentrations of active gibberellin levels will significantly reduce the tolerance of rice to alkali stress and heat stress, and only medium active gibberellin levels can significantly increase the tolerance of rice to alkali and heat stress). An appropriate concentration is required to maximize the alkali and high temperature resistance.

[0025] 6. Currently, rice or wheat grown are semi-dwarfed (caused by low gibberellin levels or disruption of gibberellin signaling pathways), and alkaline stress will further inhibit the synthesis of active gibberellins, making semi-dwarf crops particularly sensitive to stress and having low resistance. The present application found that applying low concentrations of active gibberellins in vitro can enhance rice alkaline stress tolerance, while high concentrations of active gibberellins can reduce alkaline stress tolerance.

[0026] 7. Although the present application emphasizes that applying active gibberellins in vitro to rice in alkaline soil can reduce rice yield losses in alkaline soil, similarly, methods similar to the present invention can also be used in other crops to reduce crop yield losses in alkaline soil. It is expected to be widely used in agricultural production to improve the stress tolerance of crops and reduce yield losses, and generate huge economic and social benefits in the context of global warming and increasing saline-alkali land. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Alkali-heat tolerance of Longtepu under exogenous gibberellin treatment

[0028] Figure 2 Alkali-heat tolerance of Longtepu under exogenous gibberellins and paclobutrazol treatments

[0029] Figure 3 Compensatory effect of gibberellins on rice yield under alkaline stress. DETAILED DESCRIPTION

[0030] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] Experiment on the treatment of rice with exogenous gibberellin and paclobutrazol

[0033] After 6 days of hydroponic culture, different amounts of GA3 or paclobutrazol (PAC) were added to the water culture medium of rice variety 'Longtepu' (LTP), with final concentrations of 0, 0.001, 0.01, 0.1 and 1 μM, respectively. GA3 or paclobutrazol, 6 days after treatment, start alkali or heat treatment: For alkali treatment: add 1×Yoshida nutrient solution to sodium bicarbonate in 12-day-old rice seedlings (seedlings grow to one leaf and one heart), ensure that the final concentration of sodium bicarbonate in the nutrient solution is 65mM, treat for 7-14 days, replace the alkali treatment solution every four days, and stop alkali treatment when the rice leaves begin to turn yellow, curl, and wither; For heat treatment: place the 12-day-old rice seedlings in a heat treatment box at 42°C and 90% humidity for 20-30 hours (due to different rice varieties' tolerance to heat stress, and the growth state of the seedlings will also affect the results, there is no absolute time point, and the heat treatment needs to adjust the treatment time according to the specific situation of the treatment, ranging from about 20-30 hours), and stop heat treatment when the leaves begin to curl. Recover for 7-14 days, take pictures and count the survival rate. Survival rate = surviving trees / total number of trees. The survival standard is that after 7 days of recovery, some leaves still remain green and new young leaves can grow. In each treatment process, 24 seeds were sown in one biological group (i.e., hydroponic planting was adopted after seed germination), and 3 biological replicates were set.

[0034] In this example, the alkali-heat tolerance of Longtepu under exogenous gibberellin treatment is as follows: Figure 1 As shown, Figure 1 In the figure, (AC) are the phenotypes (A) and survival rates (B and C) of Long Te Pu treated with different concentrations of GA3 under alkaline stress and high temperature stress. Alkaline treatment, 65 mM sodium bicarbonate treatment for 14 days; high temperature treatment, 42 ° C, RH>90% treatment for 28 hours, scale bar, 10 cm. Data are mean ± standard deviation, n = 3 replicates, each replicate consists of 24 rice seedlings, the same letter indicates no significant difference, and the significant difference was determined by Statix8.0 analysis and post hoc pairwise multiple comparison test (LSD<0.05).

[0035] Alkali-heat tolerance of Longtepu under exogenous gibberellin and paclobutrazol treatments Figure 2 As shown, Figure 2Figure 3. (AF) Phenotypes (A, D) and survival rates (B and C, E and F) of Long Te Pu treated with different concentrations of GA3 and PAC (paclobutrazol) under alkaline stress and high temperature stress. Alkaline treatment, 65 mM sodium bicarbonate for 14 days; high temperature treatment, 42 °C, RH>90% for 28 hours. Scale bar, 10 cm. Data are mean ± SD, n = 3 replicates, each replicate consisting of 24 rice seedlings. The same letter indicates no significant difference. Significant differences were determined by Statix8.0 analysis and post hoc pairwise multiple comparison test (LSD < 0.05).

[0036] The rice variety "Long Te Pu" was treated with 0.001-10 μM active gibberellin GA3 or paclobutrazol, and then the alkali-heat resistance was identified. Figure 1 , Figure 2 The results showed that although the application of 0.001μM and 0.01μM active gibberellin GA3 showed enhanced alkali and heat resistance, when 0.1μM concentration of active gibberellin GA3 was applied in vitro, Longtepu showed the strongest rice alkali-heat tolerance, while Longtepu alkali-heat tolerance was significantly reduced after treatment with 1 or 10μM GA3 or 0.1, 1 and 10μM paclobutrazol (inhibiting the synthesis of active gibberellin). There was no significant difference in Longtepu alkali-heat tolerance between 1 and 10μM GA3 treatments ( Figure 1 , Figure 2 ). The heat tolerance of 1 and 10 μM paclobutrazol treated rice was significantly lower than that of 0.1 μM paclobutrazol treated Long Te Pu, and the alkali tolerance of 10 μM paclobutrazol treated rice was significantly lower than that of 0.1 and 1 μM paclobutrazol treated Long Te Pu. These experimental results show that the concentration of active gibberellins is the key to the alkali-heat tolerance of rice, and maintaining the optimal moderate active gibberellin level can significantly enhance the alkali-heat tolerance of rice.

[0037] Example 2

[0038] Experiment on gibberellin supplementation under alkaline stress

[0039] In the artificial climate room, two rice varieties, 'Longtepu' and 'Songxianggengdao', were cultivated to the booting stage through transfer boxes. 5L of 100mM sodium bicarbonate solution was added to each transfer box. No sodium bicarbonate solution was added as a blank control. Rice seedlings with sodium bicarbonate were selected and 1μM GA3 (active gibberellin) solution was sprayed on the stems once a week until all matured. 'Songxianggengdao' was sprayed 5 times and 'Longtepu' was sprayed 6 times. Cultivate rice to maturity and investigate related agronomic traits. Select 10 plants to investigate the yield per plant, and measure the yield per plant as well as plant height, number of tillers, panicle length, number of panicles, fruit set rate, 1000-grain weight, grain length, and grain width.

[0040] Figure 3 The compensatory effect of gibberellins on rice yield under alkaline stress. Figure 3 (AD) Plant type (upper part, scale bar, 1m) and panicle type (lower part, scale bar 10cm) (AB) and yield per plant (CD) of 'Longtepu' (A and C) and 'Songxianggengdao' (B and D) after alkali treatment in the field under the application of gibberellins in vitro. Data of CD are mean ± SD, n = 20 plants, two-tailed t-test was used for significant difference test, *p < 0.05, **P < 0.01, ns, no significant difference.

[0041] Table 1 Compensatory effect of gibberellins on rice yield traits under alkaline stress

[0042]

[0043] Two representative rice varieties, Longtepu (indica rice variety) and Songxiangjing (japonica rice variety), were treated with 1 μM active gibberellin in vitro during the entire growth period to investigate its effects on grain yield and related agronomic traits under alkaline stress. After Longtepu and Songxiangjing were subjected to alkaline stress, the yield per plant of rice decreased significantly, while the application of active gibberellin GA3 in vitro could significantly compensate for the yield loss caused by alkaline stress, basically reaching the yield of rice without alkaline stress. Further analysis of related agronomic traits showed that the application of active gibberellin in vitro under alkaline stress could compensate for the changes in the number of panicles, thousand-grain weight, and grain shape caused by alkaline stress. These experimental results further indicate that maintaining a certain level of active gibberellin in green rice varieties under alkaline stress can reduce the yield loss caused by alkaline stress.

[0044] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for reducing rice yield loss in alkaline soil, characterized in that: In vitro application of active gibberellins to rice grown in alkaline soil.

2. A method for reducing rice yield loss in alkaline soil according to claim 1, characterized in that: At the seedling stage, the concentration of active gibberellins applied in vitro to rice in alkaline soil was 0.001-10 μM.

3. A method for reducing rice yield loss in alkaline soil according to claim 2, characterized in that: At the seedling stage, the concentration of active gibberellins applied in vitro to rice in alkaline soil was 0.1 μM.

4. The method for reducing rice yield loss in alkaline soil according to claim 1, characterized in that: Active gibberellins were applied in vitro to rice plants grown in alkaline soil at a concentration of 1 μM at maturity.

5. The method for reducing rice yield loss in alkaline soil according to claim 1, characterized in that: The active gibberellin is gibberellin GA3.

6. The method for reducing rice yield loss in alkaline soil according to claim 1, characterized in that: Active gibberellins were applied in vitro to rice plants grown in alkaline soil under high temperature conditions at the seedling or maturity stage.

7. The method for reducing rice yield loss in alkaline soil according to claim 1, characterized in that: The method of applying active gibberellins is to spray active gibberellins liquid solution on the stems.

8. The method for reducing rice yield loss in alkaline soil according to claim 1, characterized in that: The method of applying active gibberellins is: spray once a week.

9. The method for reducing rice yield loss in alkaline soil according to claim 1, characterized in that: Applying active gibberellins in vitro to rice in alkaline soil during the seedling or mature stage can increase the number of grains per rice panicle, improve the alkali resistance of rice, and reduce the yield loss caused by alkaline stress.

10. The method for reducing rice yield loss in alkaline soil according to claim 1, characterized in that: The rice is selected from Longtepu variety or Songxianggengdao variety.

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