Method for improving emergence rate of paddy rice seeds during waterflooding direct seeding

Abstract

The invention belongs to the field of crop stress resistance, and particularly relates to a method for increasing the emergence rate of paddy rice seeds directly sown in water. Comprising the following steps: soaking rice seeds in a 75-125-fold solution diluted by 10% v / v pyroligneous liquor for 36-60 hours, replacing a seed soaking agent every 24 hours, and accelerating germination of the soaked rice seeds in a moisture and heat preservation environment until the bud length is 2-5 mm. The 10% v / v pyroligneous solution with the dilution concentration of 75-125 times significantly improves the waterflooding seedling emergence ability of the rice seeds, and has a certain application prospect.

Description

Technical Field

[0001] The invention belongs to the field of crop stress resistance and relates to a method for improving the germination rate of flooded direct seeding of rice seeds. Background Art

[0002] Rice is one of the most important food crops in the world. However, in recent years, the mobility of the working population, the reduction in the number of labor forces, and the intensification of population aging have posed severe challenges to rice production. Direct seeding cultivation technology has become a technology that farmers spontaneously choose and is widely promoted due to its obvious labor-saving and cost-saving advantages. However, since the seed germination and emergence stage is the most vulnerable stage in the crop life cycle, this stage is most susceptible to various biological and abiotic stresses. The flatness of the rice field surface is a key factor affecting direct seeding of rice. The unevenness of the field makes it easy for low-lying areas to accumulate water. If there is continuous rain after sowing, the flooding stress will be further aggravated. Flooding stress may occur in all growth stages of rice, and its impact on crop growth varies depending on the growth stage and plant growth conditions. Especially in the seed germination and emergence stage, the hypoxia stress caused by flooding slows down seed germination and increases the incidence of dead and rotten seedlings, which leads to problems such as a decrease in seed emergence rate and low seedling quality in the waterlogged area of ​​the direct seeding rice field.

[0003] Wood vinegar is a by-product of the carbonization process of wood. The reddish-brown liquid obtained by condensing the smoke produced during the carbonization process is wood vinegar. With the development of modern industry, wood vinegar can be prepared not only from wood, but also from other biological materials, such as fruit shells, straw, bamboo, corn cobs and other agricultural by-products. The organic components of wood vinegar prepared from various biological materials are slightly different, but the main components are generally the same, containing more than 200 organic components such as organic acids, phenols, ketones, aldehydes, alcohols, esters, etc. Take peach wood vinegar as an example. Its main components are organic acids and phenols, accounting for 30.78% and 32.68% respectively. The content of ketones is also high, accounting for 14.97%, and there are also small amounts of alcohols, esters and nitrogen-containing compounds. The rich ingredients of wood vinegar determine its wide range of uses, and wood vinegar is low in price, non-toxic, harmless, environmentally friendly, and easy to obtain. In recent years, the production and consumption of wood vinegar has increased year by year, and it has been used in agriculture, forestry, animal husbandry, medicine and chemical industries.

[0004] In recent years, wood vinegar has received widespread attention as a new type of plant growth regulator. It has achieved remarkable results in promoting plant growth and development, anti-aging, and reducing abiotic and biotic stresses. For example, Du Jiayan et al. found that soaking seeds in wood vinegar diluted 100-500 times can significantly increase the germination rate of pepper seeds (Du Jiayan, Wu Juping, Wang Jingyao, Geng Liping, Li Bowen, Liu Wenju. Study on the effect of wood vinegar on pepper seed germination and its antibacterial effect. Journal of Hebei Agricultural University, 2021); Ma Mengyao et al. found that using wood vinegar to prime sheep grass seeds can significantly increase the germination rate of sheep grass seeds under salt stress (Ma Mengyao, Ma Hongyuan, Li Shaoyang, Qi Wenwen, Zhao Dandan. Wood Effects of vinegar on seed germination and seedling growth of Leymus chinensis under salt stress. Journal of Ecology, 2022(008):041); Wang Hongyan et al. sprayed rice seedlings with 400-fold diluted wood vinegar and found that the appropriate concentration of wood vinegar could improve the cold resistance of rice seedlings (Wang Hongyan, Chen Lin, Ma Xiaowei, Liu Xibo, Zhang Yuepei, Quan Xin, Shan Jianrong, Zhao Wei. Effects of wood vinegar on cold resistance of rice seedlings under low temperature stress. Journal of Northeast Agricultural University, 2019, 50(2):8.). However, so far, there has been no application of using wood vinegar to soak seeds to improve the ability of rice to withstand flooding. Summary of the invention

[0005] The main problem to be solved by the invention is how to improve the flooding resistance and germination ability of rice seeds.

[0006] The present invention provides the following technical solutions:

[0007] The first aspect of the present invention provides the use of wood vinegar in improving the emergence rate of rice direct seeding under flooding.

[0008] The second aspect of the present invention provides a method for improving the emergence rate of flooded direct seeding of rice. The method comprises the following steps: using 10% v / v wood vinegar diluted to a concentration of 75-125 times as a seed soaking agent to soak rice seeds at 25°C for 48 hours, replacing the seed soaking agent every 24 hours during the soaking process, and soaking the seeds for 60 hours when the average temperature of the day is lower than 20°C; soaking the seeds for 48 hours when the average temperature of the day is 23-25°C; and soaking the seeds for 36 hours when the average temperature of the day is higher than 25°C. After soaking, the rice seeds are rinsed with clean water and placed in an environment of 32°C-35°C for moisture-keeping and germination treatment until the buds are 2-5 mm long. The germinated and whitened seeds are evenly placed under flooding conditions for culture.

[0009] A fungicide may also be added to the wood vinegar, and the process of adding the fungicide to the wood vinegar is as follows: 2 ml of 25% prochloraz emulsifiable concentrate is added to 4-6 kg of diluted wood vinegar to make a 2000-3000 times solution, or 10 g of 10% imidacloprid wettable powder is added to 3-5 kg ​​of diluted wood vinegar to make a 300-500 times solution. The mixture of wood vinegar and fungicide can significantly improve the inhibitory effect on pathogens and provide more comprehensive protection for plants.

[0010] In the above method, the rice seed flooding germination ability is manifested in seed sprout survival rate, germination rate, sprout length and dry weight.

[0011] The evaluation criteria for the survival rate and emergence rate of the seedlings are that the seedlings whose coleoptiles can split and reveal the first leaf after being flooded with 6 cm water for 7 days are considered to have emerged, and the seeds whose embryo structure is intact and remains upright are considered to have survived. On the 7th day after sowing, 10 representative rice seedlings were taken from each treatment, and the sprout length and dry weight were measured to evaluate the germination ability.

[0012] The calculation formulas for the emergence rate and survival rate are as follows:

[0013] Seedling emergence rate (%) = (number of seedlings emerged 7 days after sowing / number of seeds tested) × 100.

[0014] Survival rate (%) = (number of surviving seeds 7 days after sowing / number of seeds tested) × 100.

[0015] Beneficial effects of the present invention:

[0016] The present invention uses a specific seed soaking agent to treat rice seeds before sowing, and proposes an optimal seed soaking method that can significantly improve the flooding resistance and germination ability of rice seeds by optimizing the seed soaking conditions. The optimal seed soaking conditions are: soaking the rice seeds in a 75-125 times diluted wood vinegar solution at 25°C in the dark for 48 hours, then germinating at 30°C until the buds are 3-5mm long, and then flooding and sowing. The method has the advantages of simple operation, easy control of seed soaking conditions, low cost, etc., and is of great significance to the flooding resistance and germination of rice seeds. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the stock solution of wood vinegar;

[0018] Figure 2 The morphological differences of seedlings soaked in different concentrations of wood vinegar after 7 days of flooding stress;

[0019] Figure 3 The effect of different concentrations of wood vinegar on agronomic traits of seeds after 7 days of flooding stress.

[0020] Figure 4 The difference in water conductivity when seeds were soaked in different concentrations of wood vinegar under flooding stress for 1-7 days. DETAILED DESCRIPTION

[0021] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0022] Example 1 Method for improving the ability of rice seeds to withstand flooding and germinate

[0023] 1. Test varieties

[0024] Zhongjia No. 8 (S1, japonica rice), Zhongjia Zao 17 (S2, indica rice)

[0025] 2. Pre-sowing treatment

[0026] Select rice seeds with good development, full grains, complete appearance and no damage for standby use; the selected rice seeds are placed in a 250mL beaker, pure water and wood vinegar with different concentration gradients (specific concentrations are shown in Table 1) are added to the beaker and soaked at 25°C for 48 hours, and the soaking agent is replaced every 24 hours. After soaking, the rice seeds are taken out and repeatedly rinsed with distilled water. The soaked seeds are placed in a culture dish with three layers of filter paper for germination until the buds are 3-5 mm long.

[0027] Table 1. Different seed soaking agents and wood vinegar concentration settings

[0028]

[0029] 3. Germination test

[0030] Select 100 seeds after germination and spread them in a 250mL beaker, repeat 3 times, and inject deionized water to a 6cm water layer, so that the top of the seed embryo is more than 5cm away from the water surface. After sowing, place it in a light incubator for 7 days. The culture environment is set as follows: 12h of light, 25℃, 12h of darkness, 20℃. The light intensity is 10000lx, and the relative humidity of the air in the incubator is 70%. The water is not changed during the test, and the beaker is filled with water to the scale line in time. After the germination test, the survival rate and germination rate are counted, and the bud length and dry weight are measured.

[0031] 4. Agronomic traits

[0032] The emergence rate and survival rate were determined 7 days after sowing. Seedlings whose coleoptiles could split and reveal the first leaf were defined as emerged, and seeds whose coleoptiles were intact and remained upright were defined as survived.

[0033] Seedling emergence rate (%) = (number of seedlings emerged 7 days after sowing / number of seeds tested) × 100.

[0034] Survival rate (%) = (number of surviving seeds 7 days after sowing / number of seeds tested) × 100.

[0035] On the 7th day after sowing, 10 representative rice seedlings were selected from each treatment and their sprout lengths were measured.

[0036] 5. Water conductivity

[0037] The water conductivity was measured every day after sowing using a conductivity meter (DDA-11A; Shanghai Hongyi Instrument Technology Co., Ltd.).

[0038] The results of the screening experiment on the suitable concentration of wood vinegar are as follows:

[0039] 1) Differences in agronomic traits after 7 days of waterlogging stress

[0040] As shown in Table 2, after 7 days of flooding, except for the 25-fold dilution of wood vinegar, the rice seeds died due to toxic damage caused by the high concentration, the germination rate, survival rate, and bud length of the rice seeds soaked in the other dilutions were significantly higher than those in the pure water soaking (CK) treatment, and there were significant differences in agronomic traits between the dilutions. For S1, C3 and C4 had the best soaking effect, which increased the germination rate by 62.33% and 60.00%, the survival rate by 25.66% and 27.33%, and the bud length by 50.55% and 38.73% compared with the pure water soaking. There were also differences among varieties. For S2, soaking seeds in wood vinegar had a better effect on promoting the germination of rice seeds. When wood vinegar was diluted 50-150 times, its germination rate and survival rate were significantly improved. Among them, C4 had the most significant promoting effect. Compared with soaking seeds in pure water, it increased the germination rate by 50.67%, the survival rate by 41.33%, and the bud length by 110.80%.

[0041] Table 2 Effects of soaking seeds with different concentrations of wood vinegar on the survival rate, germination rate and sprout length of rice seeds

[0042]

[0043] 2) Water conductivity after flooding for 1-7 days

[0044] like Figure 3As shown in the figure, with the extension of flooding stress time, the water conductivity in the rice growth environment under different treatments showed a continuous upward trend. Seed soaking with wood vinegar alleviated the damage of flooding stress to the cell plasma membrane to a certain extent and maintained the stability of the cell membrane. In the treatment of wood vinegar with various dilution ratios, except for the 25-fold dilution of wood vinegar, which had a direct toxic effect on rice seeds due to excessive concentration and caused seed death, all other dilution ratios of wood vinegar treatment significantly reduced the water conductivity, and C2 and C3 had the best mitigation effect, indicating that the appropriate concentration of wood vinegar treatment of rice seeds can effectively alleviate the oxidative damage of flooding stress to the cell membrane.

[0045] In summary, through 7 days of flooding culture, it was found that compared with the control, rice seeds treated with wood vinegar had higher flooding resistance at appropriate concentrations. The optimal concentration for Zhongjia No. 8 and Zhongjia Zao 17 was 100 times diluted.

[0046] Example 2: Verification test on the ability of soaking seeds in wood vinegar to improve the ability of rice seeds to withstand flooding and germinate

[0047] Based on the experiment of soaking seeds with different concentrations of wood vinegar, 12 varieties of indica rice, japonica rice, and indica-japonica hybrid rice were used for the experiment. The variety selection is shown in Table 3. The seeds were soaked with 100-fold dilution of wood vinegar (100×, the optimal concentration screened) with deionized water (CK) to verify the effectiveness of wood vinegar in promoting rice seed germination. The soaking, germination, culture method and culture environment are the same as those in Example 1.

[0048] Table 3. Validation test varieties

[0049]

[0050] The verification test results are as follows:

[0051] The effectiveness of wood vinegar seed soaking was verified by diluting 100 times of wood vinegar. Compared with the control, the emergence rate of each flood-sensitive variety was significantly higher than that of the control. There was no significant difference in the three flood-tolerant japonica rice varieties, but the emergence rate of wood vinegar seed soaking was also higher than that of the control. Looking at the types of varieties, wood vinegar treatment of various indica rice varieties has a significant effect on improving the ability of rice seeds to withstand flooding, with the emergence rate, bud length, and dry weight increased by 64.0%-85.7%, 55.2%-287.1%, and 64.8%, respectively. For japonica rice, the three tested japonica rice varieties were all flood-tolerant varieties, and the difference in germination rate was not significant, but the improvement of germination ability by wood vinegar treatment was reflected in bud length and dry weight, which increased by 5.1%-37.1% and 10.1-16.5%. The flood-sensitive japonica rice variety Zhejing 99 showed the same performance as the indica rice varieties, with significant improvements in germination rate, bud length and dry weight, which increased by 64.3%, 177.3% and 96.4% respectively. Wood vinegar also had a significant effect on improving the flood-tolerant germination ability of indica-japonica hybrid rice, with its germination rate, bud length and dry weight increased by 31.3%-87.7%, 4.9%-109.0% and 8.5%-20.8% respectively.

[0052] Table 4. Differences in agronomic traits of seeds soaked in 100-fold diluted wood vinegar

[0053]

[0054] It can be seen from Examples 1 and 2 that soaking seeds with low concentrations of wood vinegar of the present invention can improve the ability of rice seeds to withstand flooding and germinate; soaking seeds with low concentrations of wood vinegar can significantly improve the germination rate, bud length, and dry weight of rice seeds under flooding stress and reduce the degree of damage to rice seeds.

[0055] Obviously, the above described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, ordinary technicians in this field can make other different forms of changes or modifications without making creative work, which should fall within the scope of invention protection.

Claims

1. Application of wood vinegar in improving the emergence rate of rice direct seeding under flooding.

2. A method for improving the emergence rate of rice direct seeding under flooding, characterized in that: The method comprises the following steps: using 10% v / v wood vinegar diluted to a concentration of 75-125 times as a seed soaking agent to soak rice seeds at 25° C. for 48 hours, and replacing the seed soaking agent every 24 hours during the soaking process; rinsing the rice seeds with clean water after soaking, and placing the rice seeds in an environment of 32° C.-35° C. for moisture-keeping and germination treatment until the buds are 2-5 mm long; and evenly placing the germinated and whitened seeds under flooding conditions for cultivation.

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