CN104350834A - Seed soaking treatment method for increasing germination rate of corn seeds - Google Patents

Abstract

A seed soaking treatment method for improving the germination rate of corn seeds on top of the soil is carried out according to the following five steps: one is seed selection and pretreatment, and the other is preparation of soaking liquid, which is divided into preparation of common corn soaking liquid and sweet corn soaking liquid Two kinds of corns respectively have three kinds of hormones, i.e. gibberellin, indole acetic acid, and brassinosteroids. Sow immediately or return to dry. Soaking corn seeds with this method is simple and convenient, has a short cycle and quick results, and can be effective regardless of the moisture content. To a certain extent, it can be regarded as a supplementary means for variety improvement. It is low in cost, labor-saving, and is not affected by regions and climates. restrict.

Description

Seed Soaking Treatment Method for Improving the Germination Rate of Corn Seeds Top Soil

technical field

The invention relates to a pretreatment method of crop seeds before sowing, in particular to a seed soaking treatment method which is beneficial to improving the germination rate of corn seeds on top of soil.

Background technique

Corn is the crop with the largest sown area in my country. It is stable at about 500 million mu all year round, but it is mostly distributed in arid and semi-arid areas that account for 2/3 of the country's cultivated land area. The soil surface evaporation in the dry corn area is greater than the precipitation, and 90% of the years cannot be planted in time due to insufficient moisture. Monitoring data show that the average relative water content of the 0-20cm soil layer in the main corn-producing areas of North my country, Northeast China, and Northwest China is only about 50%, and the dry area is expanding and tends to move southward, which brings great difficulties to corn sowing. Although there are some traditional drought-resistant sowing methods in production, such as moisture exploration and deep sowing, the seeds of existing varieties have poor ability to top the soil, and it is difficult to emerge from deep sowing, resulting in the phenomenon of lack of seedlings and broken ridges. In serious years, the lack of seedlings can reach 40% to 50%. , which directly affects the harvest of corn. Cultivating new varieties of maize with strong soil topping ability is one of the effective ways to deal with the current severe drought. However, due to the high cost of breeding, the large amount of labor input, and the constraints of the region and climate, especially the long cycle, ranging from 5-8 years to more than 10 years, it may even face the risk of failure. At present, my country has only bred a few corn varieties with strong soil topping ability, such as "Kang 38", "40107", "Hanyu No. 5", etc., and most of them were selected in the 1990s. Due to the restriction of the application cycle of varieties, these varieties have gradually withdrawn from the market.

It is reported that seed soaking treatment can promote the germination of maize seeds under normal sowing conditions to a certain extent, but there is no report on improving the germination rate of maize seeds under deep sowing conditions. As we all know, the normal sowing depth of common corn is only 2-5cm. But for sweet corn, even if the sowing depth is only 2cm, the seeds may not be able to push out of the soil to germinate. When the situation is serious, they can only be transplanted. This severe reality of corn production has brought agricultural scientists a real problem to be solved to improve the vigor of corn seeds and promote the efficiency of top soil germination. In this regard, the applicant has done some work, which is now disclosed to the world in the form of a patent application.

Contents of the invention

The technical problem to be solved by the present invention is to provide a seed soaking treatment method for improving the germination rate of corn seeds on top of the soil.

To solve the above technical problems, the following technical solutions are adopted:

1. a kind of soaking treatment method that improves corn seed top soil germination rate, it is characterized in that carry out as follows:

(1) Seed selection and pretreatment: choose corn that is free from pests and diseases, full of grains, and undamaged and stored for 1-3 years as seeds, and use a sodium hypochlorite aqueous solution with a mass ratio concentration of 1% as a disinfectant, soak for 10 minutes, and take it out. Rinse with clean water and drain;

(2) Preparation of soaking solution:

Preparation of ordinary corn soaking liquid: if the hormone aqueous solution is used as the soaking liquid, the mass-volume ratios of the hormone and clean water are:

① The concentration of gibberellin (GA ₃ ) soaking solution is 0.15-0.20g/L,

②The concentration of indole acetic acid (IAA) soaking solution is (1.5-2.0)×10 ^-5 g/L,

③The concentration of brassinosteroid (BR) soaking solution is (4.5-5.1)×10 ^-4 g/L,

Choose one of the three soaking solutions;

Preparation of sweet corn soaking solution: if the hormone aqueous solution is used as the soaking solution, the mass-volume ratio of the hormone to clean water is:

① The concentration of gibberellin (GA ₃ ) soaking solution is 0.03-0.04g/L,

②The concentration of indole acetic acid (IAA) soaking solution is (1.6-2.0)×10 ^-4 g/L,

③The concentration of brassinosteroid (BR) soaking solution is (4.5-5)×10 ^-4 g/L,

Choose one of the three soaking solutions;

(3) Determination of the consumption of soaking liquid and the weight ratio of air-dried seeds: soaking liquid: seed=100ml: (50-100) g;

(4) Soaking: Submerge the seeds in the soaking solution and soak for 18-30 hours in the dark at a temperature of 23±2°C, stirring during the period to ensure the uniformity of soaking the seeds;

(5) Sowing or re-drying: After soaking the seeds, they can be sown immediately, or they can be re-dried for later use. When re-drying, take out the soaked seeds, spread them on paper towels or towels, and spread them for 48 hours at 23±2°C. ±2h, put it in a refrigerator at 4°C for storage until use.

The beneficial effects of the invention are: the method is simple to operate, easy to master, extremely short in cycle, quick in effect, can achieve remarkable effects in soil with good or bad moisture content, and has great value for popularization and application. The method can be used as a supplementary means of the genetic improvement method, greatly reduces the cost and labor to a certain extent, and is not restricted by regions and climates.

Description of drawings

Fig. 1 is a graph comparing the germination rate of corn seeds after deep sowing with different seed soaking methods.

Fig. 2 The change curve of electrical conductivity of common corn Nongda 108 seed extract after GA ₃ soaking and drying.

Fig. 3 The change curve of the electrical conductivity of the super sweet corn super sweet No. 3 seed extract after soaking the IAA seeds and returning to drying.

Fig. 4 is a graph comparing the dehydrogenase activity of corn seeds treated by different seed soaking methods.

Fig. 5 Oxygen consumption curves of common corn Nongda 108 seeds treated by different seed soaking methods. Fig. 6 Oxygen consumption curves of sweet corn Chaotian No. 3 seeds treated by different seed soaking methods.

Detailed ways

The present invention is described in detail below in conjunction with embodiment and with reference to accompanying drawing: 1. a kind of soaking treatment method that improves corn seed top soil germination rate, it is characterized in that carry out as follows:

(1) Seed selection and pretreatment: choose corn that is free from pests and diseases, full of grains, and undamaged and stored for 1-3 years as seeds, and use a sodium hypochlorite aqueous solution with a mass ratio concentration of 1% as a disinfectant, soak for 10 minutes, and take it out. Rinse with clean water and drain;

(2) Preparation of soaking solution:

Preparation of ordinary corn soaking liquid: if the hormone aqueous solution is used as the soaking liquid, the mass-volume ratios of the hormone and clean water are:

① The concentration of gibberellin (GA ₃ ) soaking solution is 0.15-0.20g/L,

②The concentration of indole acetic acid (IAA) soaking solution is (1.5-2.0)×10 ^-5 g/L,

③The concentration of brassinosteroid (BR) soaking solution is (4.5-5.1)×10 ^-4 g/L,

Choose one of the three soaking solutions;

Preparation of sweet corn soaking solution: if the hormone aqueous solution is used as the soaking solution, the mass-volume ratio of the hormone to clean water is:

① The concentration of gibberellin (GA3) soaking solution is 0.03-0.04g/L,

②The concentration of indole acetic acid (IAA) soaking solution is (1.6-2.0)×10-4g/L,

③The concentration of brassinosteroid (BR) soaking solution is (4.5-5)×10-4g/L,

Choose one of the three soaking solutions;

(3) Determination of the consumption of soaking liquid and the weight ratio of air-dried seeds: soaking liquid: seed=100ml: (50-100) g;

(4) Soaking: Submerge the seeds in the soaking solution and soak for 18-30 hours in the dark at a temperature of 23±2°C, stirring during the period to ensure the uniformity of soaking the seeds;

(5) Sowing or re-drying: After soaking the seeds, they can be sown immediately, or they can be re-dried for later use. When re-drying, take out the soaked seeds, spread them on paper towels or towels, and spread them for 48 hours at 23±2°C. ±2h, put it in a refrigerator at 4°C for storage until use.

In order to prove and confirm the feasibility of this method, the applicant has done a series of comparative experiments, which are now introduced as follows:

1 Introduction

Seeds under deep sowing conditions must extend the corresponding organs to push out of the soil, which is the key for crop seeds to top the soil. The extension organs are different for different crops. The mesocotyls of sorghum elongate under deep sowing conditions to make the seedlings emerge from the soil, but the mesocotyls of wheat and barley hardly elongate under deep sowing conditions, on the contrary, the first internode and coleoptile elongate significantly. The obvious characteristic of the seeds of the strong top soil maize inbred line DT-26 cultivated in our laboratory is that the mesocotyl elongates significantly under deep sowing conditions, so that the seedlings can penetrate the thick soil layer and emerge.

Research and production practices have shown that plant growth hormones, such as gibberellin (GA3), indole acetic acid (IAA), and brassinolide (BR), can change the physiological structure of plants, promote cell elongation and growth, and improve plant stress. resistance. According to research, gibberellin has a significant effect on promoting the elongation of plant cells, and has an important impact on seed germination and seed vigor. Gibberellin can increase the content of IAA in plants, induce the synthesis of α-amylase in seeds, and accelerate The hydrolysis of starch accelerates cell division and differentiation to promote seed germination. Low-concentration indole acetic acid can promote cell division, accelerate cell metabolism, and promote plant growth. Numerous experiments have proved that brassinosteroids have high physiological activity. At extremely low concentrations, they can significantly promote cell division and elongation, participate in the regulation of various biochemical processes in plants, and have a significant role in promoting crop growth. Brassinolide compounds have been studied and applied in corn production. Soaking seeds with brassinosteroids can reduce the loss of maize caused by drought.

According to the characteristic that three types of hormones can promote cell growth, different concentrations of hormone solutions were used to treat corn seeds, and the optimum concentration to improve the ability of corn to top soil was determined through germination tests at different sowing depths, and the physiological mechanism of hormone-promoting effects was explored. To provide a scientific basis for the new production method of improving the germination rate of top soil for dry-farmed corn.

2 Materials and methods

2.1 Materials

Ordinary corn variety: Nongda 108, super sweet corn variety: Super Sweet No. 3, seeds purchased from Zhejiang Nongke Seed Industry Co., Ltd.

2.2 Method

2.2.1 Seed treatment methods and germination conditions

Gibberellin (GA ₃ ), indole acetic acid (IAA), and brassinolide (BR) were all analytically pure, with molecular weights of 346.37, 175.19, and 480.68, respectively. According to the characteristics of the three hormones, use different concentrations of hormone solutions to treat corn seeds to determine the optimum concentration that can improve the ability of corn to top the soil. The specific methods are as follows:

(1) Hormone concentration:

(2) Sowing depth

(3) Sand trigger material treatment

After the river sand is sieved to remove impurities, it is dried in an oven for 4 hours. Before planting, mix the appropriate amount of water until the sand is in a certain cohesive state.

(4) Seed germination

Germinate under 12h light/12h dark at 25°C, count the number of germinations every day after emergence, and measure seedling length and weight after 10 days. The experiment was repeated 3 times. During this period, pay attention to the moisturizing of the sand bed to prevent the surface of the sand bed from being compacted and causing damage to the top of the corn buds.

a. Germination potential: 6d emergence rate

b. Germination rate: 10d emergence rate

c. Germination index (GI) = ∑Gt/Dt Gt: the number of germinations of the day Dt: the number of days of germination

d. Vitality index (VI) = GI × S GI: germination index S: seedling length (cm) or seedling weight (g) within a certain period of time

e. Mesocotyl length: 10 germinated seeds were randomly selected on the 10th day, and the length of the mesocotyl was measured.

2.2.2 Determination of electrical conductivity

The electrical conductivity was measured with a DDS-307 electrical conductivity meter, taking 50 seeds each of the seeds treated with the optimum concentration of each hormone, unsoaked seeds, and water-soaked seeds, repeated 3 times, and measured at 12h, 24h, and 36h after soaking the seeds respectively, and the calculation unit Conductivity of weight seed leach solution.

2.2.3 Dehydrogenase activity assay

After soaking the seeds of "Nongda 108" and "Super Sweet 3" at 25°C for 24 hours, 10 seeds were randomly selected, cut longitudinally along the central axis, and then put into test tubes, and 10ml of 0.2 % triphenyltetrazolium (TTC) reagent, stopper the test tube, and stain at 25°C for 24h. Then the embryos of the seeds were taken out and washed three times with distilled water, and then 10ml of absolute ethanol was added, and placed at 25°C for 24h. Finally, the OD value of the extract was measured with a spectrophotometer under 490nm ultraviolet light, and repeated three times.

2.2.4 Oxygen sensing measurement

48 seeds under each treatment were randomly selected, and 4 repetitions were set, and each seed was respectively placed in a 2.0ml test tube containing 1ml 0.5% agar medium. Cover tightly with a sealed lid and place it at 25°C, and set up two controls, the positive control is a test tube without seeds, and the negative control is adding supersaturated Na ₂ SO ₃ solution in the test tube, and then automatically Measured by Q2 instrument (ASTECGlobal, Holland) every hour. In order to emphasize comparability, the oxygen concentration measured in real time is expressed by relative concentration (%): the oxygen concentration in the test tube with one seed/the oxygen concentration in the test tube without seed. After measuring 72h (faster germination) for conventional seeds or 96h (slower germination) for super sweet corn seeds, the four oxygen metabolism indicators include enhanced metabolic time (IMT), oxygen metabolic rate (OMR), relative germination time (RGT) and relative germination rate (RGR) were analyzed by Q2 analysis software. In general, IMT and RGT were negatively correlated with seed vigor, while OMR and RGR were positively correlated with seed vigor.

2.2.5 Data analysis

All the data in this experiment were processed by using SAS variance analysis software and Excel software.

3 Results and Analysis

3.1 Effects of soaking seeds with different hormones on maize seed germination

3.1.1 Effect of GA ₃ soaking on maize seed germination

It can be seen from Table 1 that soaking seeds with different concentrations of gibberellin has an effect on the germination potential, germination rate, germination index, and vigor index of Nongda 108 corn seeds under the condition of 10cm sowing depth, and the concentration of 0.175g/L is the best. Compared with unsoaked seeds, the germination potential, germination rate, germination index, and vigor index of seeds after soaking with 0.175g/L GA ₃ increased by 38.1%, 34.1%, 40.4%, and 25.6%, respectively. Compared with water-soaked seeds, the germination potential, germination rate, germination index, and vigor index of seeds after soaking with 0.175g/L GA ₃ increased by 31.0%, 15.7%, 11.9%, and 9.8%, respectively. The same letter in the same column in Table 1 indicates that the difference is not significant at the p<0.05 level.

Table 1 Effect of GA ₃ soaking on seed germination of common corn Nongda 108 at 10cm sowing depth

It can be seen from Table 2 that soaking seeds with different concentrations of gibberellin had an impact on the germination potential, germination rate, germination index, and vigor index of super sweet No. good. Compared with unsoaked seeds, the germination potential, germination rate, germination index, and vigor index of seeds after soaking with 0.035g/L GA ₃ increased by 34.8%, 37.5%, 59.3%, and 61.4%, respectively. Compared with water-soaked seeds, 0.035g After soaking in /L GA ₃ , the germination potential, germination rate, germination index, and vigor index of seeds increased by 50.0%, 18.5%, 26.5%, and 39.1%, respectively. The same letter in the same column in Table 2 indicates that the difference is not significant at the p<0.05 level.

Table 2 Effect of GA ₃ soaking on seed germination of super sweet corn Chaotian 3 at 6cm sowing depth

3.1.2 Effect of IAA soaking on maize seed germination

It can be seen from Table 3 that soaking seeds with different concentrations of indole acetic acid has an effect on the germination potential, germination rate and germination index of Nongda 108 corn seeds under the condition of 10cm sowing depth, and the concentration of 1.75×10 ^-5 g/L is the best . Compared with non-soaked seeds, the germination potential, germination rate and germination index of seeds soaked with 1.75×10 ^-5 g/L IAA increased by 34.3%, 32.9%, and 38.3% respectively; compared with water-soaked seeds, 1.75×10 ^-5 After soaking with g/L IAA, the germination potential, germination rate and germination index of seeds increased by 27.4%, 14.7% and 10.2%, respectively. The same letter in the same column in Table 3 indicates that the difference is not significant at the p<0.05 level.

Table 3 Effect of IAA seed soaking on seed germination of common corn Nongda 108 under the condition of 10cm sowing depth

It can be seen from Table 4 that soaking seeds with different concentrations of indole acetic acid has an effect on the germination potential, germination rate and germination index ^of super sweet No. optimal. Compared with unsoaked seeds, the germination vigor, germination rate and germination index of seeds after soaking with 1.75×10 ^-4 g/L IAA increased by 112.5%, 23.3% and 29.6%, respectively. Compared with soaking seeds in water, the germination potential, germination rate and germination index of seeds soaked in 1.75×10 ^-4 g/L IAA increased by 41.7%, 6.2% and 2.9%, respectively. The same letter in the same column in Table 4 indicates that the difference is not significant at the p<0.05 level.

Table 4 Effect of IAA seed soaking on seed germination of super sweet corn Chaotian 3 at 6cm sowing depth

3.1.3 Effect of BR soaking on maize seed germination

It can be seen from Table 5 that soaking seeds with different concentrations of brassinosteroid had an effect on the germination potential, germination rate and germination index of Nongda 108 corn seeds under the condition of 10cm sowing depth, especially the concentration of 4.8×10 ^-4 g/L was the most good. Compared with unsoaked seeds, the germination vigor, germination rate and germination index of seeds after soaking with 4.8×10 ^-4 g/L BR increased by 25.3%, 28.3%, and 34.0%, respectively. Compared with soaking seeds in water, the germination potential, germination rate and germination index of seeds after soaking in 4.8×10 ^-4 g/L BR increased by 18.9%, 10.7%, and 6.8%, respectively. The same letter in the same column in Table 5 indicates that the difference is not significant at the p<0.05 level.

Table 5 Effect of BR soaking on seed germination of common corn Nongda 108 under 10cm sowing depth

From Table 6, we can see that soaking seeds with different concentrations of BR has an effect on the germination potential, germination rate and ^germination index of super sweet No. optimal. Compared with unsoaked seeds, the germination potential, germination rate and germination index of seeds soaked with 4.8×10 ^-4 g/L BR increased by 87.5%, 28.7%, and 44.4% respectively. Compared with water-soaked seeds, 4.8×10 ^-4 After soaking in g/L BR, the germination potential, germination rate and germination index of seeds increased by 25.0%, 10.9% and 14.7%, respectively. The same letter in the same column in Table 6 indicates that the difference is not significant at the p<0.05 level.

Table 6 Effect of BR soaking on seed germination of super sweet corn Chaotian No. 3 under the condition of 6cm sowing depth

3.1.4 Effects of different soaking methods on maize seed germination

The above test results show that for the seeds of "Nongda 108" and "Chaotian 3", the optimum concentration of GA ₃ is 0.175g/L and 0.035g/L, respectively, and the optimum concentration of IAA is 1.75×10 ^-5 g /L IAA and 1.75×10 ^-4 g/L IAA, the optimal concentration of BR was 4.8×10 ^-4 g/L. From the comparison of the best concentrations of the three hormones, 0.175g/L GA ₃ had the most obvious promoting effect on "Nongda 108", and 0.035g/L GA ₃ had the most obvious promoting effect on "Super Sweet No. 3" (Table 7 ). The same letter in the same column in Table 7 indicates that the difference is not significant at the p<0.05 level.

Compared with unsoaked seeds, the germination potential, germination rate, germination index and mesocotyl length of "Nongda 108" seeds increased by 38.1%, 35.8%, 40.4% and 26.1% respectively after soaking in 0.175g/L GA ₃ solution , increased by 34.3%, 32.9%, 38.3%, and 22.5% after soaking in 1.75×10 ^-5 g/L IAA solution, respectively increased by 25.3%, 25.3%, and 22.5% in 4.8×10 ^-4 g/L BR solution 28.3%, 34.0%, 17.6% (Table 7). The germination potential, germination rate, germination index and mesocotyl length of "Chaotian 3" seeds increased by 125.0%, 37.5%, 59.3% and 36.8% after soaking in 0.035g/L GA ₃ solution, and after 1.75 After soaking in ×10 ^-4 g/L AA solution, they increased by 112.5%, 23.3%, 29.6%, and 33.9%, respectively; after soaking in 4.8×10 ^-4 g/L BR solution, they increased by 87.5%, 28.7%, and 44.4%, respectively , 26.9%.

Compared with the seeds soaked in water, the germination potential, germination rate, germination _index and mesocotyl length of "Nongda 108" seeds increased by 31.0%, 11.8%, 11.9%, 13.8%, increased by 27.4%, 9.4%, 10.2%, and 10.6% after soaking seeds in 1.75×10 ^-5 g/L IAA solution, and increased by 18.9% after soaking seeds in 4.8×10 ^-4 g/L BR solution %, 5.6%, 6.8%, 6.1%. The germination potential, germination rate, germination index and mesocotyl length of "Chaotian 3" seeds were increased by 50.0%, 18.5%, 26.5%, and 20.0% after soaking in 0.035g/L GA ₃ solution, and after 1.75 ×10 ^-4 g/L IAA solution soaked seeds increased by 41.7%, 6.2%, 2.9%, 17.4%, respectively, after soaking 4.8×10 ^-4 g/L BR solution increased by 25.0%, 10.9%, 14.7% %, 11.3%.

Table 7 Effects of different seed soaking methods on the germination of maize seeds from deep sowing

For the sake of intuition, the deep-sowing germination rate data in Table 7 were made into a comparative coordinate diagram of the deep-sowing germination rate of corn seeds treated by different seed soaking methods, see Figure 1 for details. It should be noted that in Figure 1: the concentrations of GA ₃ , IAA, and BR used for soaking the seeds of the common corn variety "Nongda 108" are 0.175g/L, 1.75×10-5g/L, and 4.8×10-4g/L, respectively. , the concentrations of GA3, IAA, and BR used for soaking the seeds of sweet corn variety "Chaotian 3" are 0.035g/L, 1.75×10-4g/L, 4.8×10-4g/L respectively; The difference was not significant at the <0.05 level.

3.2 Effects of seed soaking with different hormones on the integrity of maize seed cell membrane

The principle of the measurement of the conductivity of the seed leachate is that in the early stage of seed imbibition, the ability of cell membrane reconstruction and damage repair affects the degree of extravasation of electrolytes and soluble substances. The faster the reconstruction of membrane integrity, the less extravasation, the smaller the conductivity value . High-viability seed soaks have lower conductivity than low-viability seeds. Taking GA ₃ , IAA and water soaking seeds as examples, the effects of different seed soaking methods on reducing electrical conductivity and improving cell membrane integrity and vitality are illustrated below.

It can be seen from Figure 2 that after soaking the seeds in 0.175g/L GA ₃ solution and water, the conductivity of the leach solution of Nongda 108 seeds decreased significantly at the three soaking times, and the conductivity of the leach solution of seeds soaked in 0.175g/L GA ₃ was the lowest. With the extension of soaking time, the conductivity of the leach solution of the three kinds of seeds increased gradually, especially the conductivity of the leach solution of the seeds soaked in 0.175g/L GA ₃ increased the slowest. The above results showed that the vigor of seeds soaked in 0.175g/L GA ₃ was the highest, followed by water soaking, and the vigor of unsoaked seeds was the lowest.

It can be seen from Fig. 3 that after soaking seeds in 1.75×10 ^-4 g/L IAA solution and water, the conductivity of Nongda 108 seeds in the leaching solution decreased significantly at three soaking times, especially when soaking in 1.75×10 ^-4 g/L IAA The conductivity of the seed extract was the lowest. With the prolongation of soaking time, the conductivity of the leachate of the three treatments increased gradually, especially the conductivity of the leachate of the seeds soaked at 1.75×10 ^-4 g/LIAA increased the slowest. The above results showed that the vigor of the seeds soaked in 1.75×10 ^-4 g/L IAA was the highest, followed by the seeds soaked in water, and the vigor of the unsoaked seeds was the lowest.

3.3 Effects of soaking seeds with different hormones on dehydrogenase activity of corn seeds

It is well known that the higher the seed dehydrogenase activity, the more vigorous the respiration of the seed and thus the higher the vigor level of the seed. In order to elucidate the effect of soaking treatment on the dehydrogenase activity of maize seeds, the embryos of the seeds were isolated and the dehydrogenase activity in the embryo was determined.

It can be seen from Figure 4 that the dehydrogenase activity in the seeds increased after soaking. Compared with unsoaked seeds, the dehydrogenase activity in the seeds of "Nongda 108" increased at 0.175g/L GA ₃ , 1.75×10 ^-5 The g/L IAA and 4.8×10 ^-4 g/L BR solutions increased by 1.3, 1.1, and 1.3 times respectively after soaking the seeds. The activity of dehydrogenase in the seeds of "Chaotian 3" increased by 3.2 and 2.9 respectively after soaking in 0.035g/L GA ₃ , 1.75×10 ^-5 g/L IAA and 4.8×10 ^-4 g/L BR solutions , 3.1 times. It should be noted that in Figure 4: the concentrations of GA ₃ , IAA, and BR used for soaking Nongda 108 seeds were 0.175 g/L, 1.75×10 ^-5 g/L, and 4.8×10 ^-4 g/L, respectively. The concentrations of GA ₃ , IAA, and BR soaked in Chaotian No. 3 seeds were 0.035g/L, 1.75×10 ^-4 g/L, 4.8×10 ^-4 g/L respectively; the same letters indicate differences at the level of p<0.05 Not obvious.

Compared with soaking seeds in water, the activity of dehydrogenase in "Nongda 108" seeds increased after soaking in 0.175g/L GA ₃ , 1.75×10 ^-5 g/L IAA, and 4.8×10 ^-4 g/L BR solutions respectively 15.4%, 10.8%, 15.4%. The activity of dehydrogenase in the seeds of "Chaotian ₃ " increased by 78.8%, 1.75×10 ^-5 g/L IAA, 4.8×10 ^-4 63.6%, 75.8%.

The above results showed that soaking seeds with hormones increased the dehydrogenase activity of maize seeds, thereby promoting the improvement of seed vigor, especially 0.175g/L GA ₃ was the most significant.

3.4 Effects of seed soaking with different hormones on respiratory metabolism during maize seed germination

Seed germination is a rather complex physiological process. During the whole germination process, the respiratory metabolism of the seeds is vigorous, therefore, oxygen is a necessary condition for the smooth germination of the seeds. All active seeds, even in a very dry or dormant state, will not stop their respiration. Any life activity of seeds is closely related to respiration, which provides energy for life activities. Once the respiration of seeds stops, the seeds die. During the whole germination process, the energy substances of seeds (mainly starch, protein, fat) must be oxidized and decomposed under aerobic conditions, converted into intermediate products of anabolism and energy required for physiological activities. It can be seen that respiration is the concentrated expression of seed physiological activity, and the strength of respiration is directly related to the level of seed vitality. Therefore, the detection of oxygen consumption during seed germination can well reflect the vigor of seeds. Oxygen sensing technology is to evaluate the vitality level of seeds according to the oxygen consumption of seeds during germination.

Germination initiation time (IMT) reflects the speed of seed imbibition and germination until radicle breaks through the seed coat. High-vigorous seeds absorb and germinate in a short period of time, and the radicle breaks through the seed coat, which is manifested by a low IMT value. Oxygen consumption rate (OMR) is the respiration rate between the time when the seed radicle breaks through the seed coat and the oxygen consumption rate slows down under hypoxic stress. High-vigorous seeds show a high OMR value. Theoretical germination time (RGT) is the theoretical germination time under non-hypoxic stress conditions, which is directly related to the actual germination time of each seed, and high vigor seeds show low RGT value. Theoretical germination rate (RGR) is the germination rate estimated based on the number of reverse S-shaped curves. The seeds with reverse S-shaped curves in the oxygen sensor detection are considered to be germinated seeds. The higher the seed vitality, the higher the RGR value.

It can be seen from Fig. 5 and Fig. 6 that for the two maize varieties, the oxygen consumption of the seeds soaked in GA ₃ is the fastest, followed by the seeds soaked in water, and the oxygen consumption of the unsoaked seeds is the slowest. In addition, the common corn variety "Nongda 108" consumed oxygen faster than the sweet corn variety "Chaotian 3".

The IMT and RGT of the common corn variety "Nongda 108" soaked in 0.175g/L GA ₃ solution and the sweet corn variety "Chaotian 3" soaked in 0.035g/L GA ₃ solution were significantly reduced. While both OMR and RGR were significantly improved (Table 8). The same letter in the same column in Table 8 indicates that the difference is not significant at the level of p<0.05. The results of this oxygen sensing test indicated that soaking seeds with exogenous GA ₃ could promote the respiration of seeds, thereby promoting seed germination under deep sowing conditions. Compared with non-soaked and water-soaked "Nongda 108" seeds, the IMT and RGT of the seeds soaked in 0.175g/L GA ₃ solution decreased by 53.8%, 57.1% and 18.7%, 19.8%, respectively, while OMR, RGR Respectively increased by 116.9%, 27.4% and 20.3%, 15.5%. Similarly, compared with the unsoaked and water-soaked "Super Sweet No. 3" seeds, the IMT and RGT of the seeds soaked in 0.035g/L solution decreased by 45.8%, 25.3%, 20.8%, and 13.4%, respectively, while OMR and RGR increased by 138.0%, 45.4% and 29.9%, 16.5% respectively.

The above results indicated that soaking seeds with GA ₃ improved the oxygen respiration metabolism level of common corn varieties and sweet corn varieties seeds, thereby improving the vigor level of seeds, especially at 0.175g/L GA ₃ (Nongda 108) or 0.035g/L GA ₃ (Super Sweet No. 3) has the most obvious soaking effect.

Table 8 Effect of seed soaking on oxygen metabolism indexes of maize seeds

Claims (1)

1. a kind of soaking treatment method that improves corn seed top soil germination rate, it is characterized in that carry out as follows: (1) Seed selection and pretreatment: Choose corn that is free from pests and diseases, has full grains, and is not damaged and has been stored for 1-3 years as seeds. Use sodium hypochlorite aqueous solution with a mass ratio of 1% as a disinfectant, soak for 10 minutes, and take it out. Rinse with clean water and drain; (2) Preparation of soaking solution: Preparation of ordinary corn soaking liquid: if the hormone aqueous solution is used as the soaking liquid, the mass-volume ratios of the hormone and clean water are: ① The concentration of gibberellin (GA ₃ ) soaking solution is 0.15-0.20g/L, ②The concentration of indole acetic acid (IAA) soaking solution is (1.5-2.0) ×10 ^-5 g/L, ③The concentration of brassinosteroid (BR) soaking solution is (4.5-5.1) ×10 ^-4 g/L, Choose one of the three soaking solutions; Preparation of sweet corn soaking solution: if the hormone aqueous solution is used as the soaking solution, the mass-volume ratio of the hormone to clean water is: ① The concentration of gibberellin (GA ₃ ) soaking solution is 0.03-0.04g/L, ②The concentration of indole acetic acid (IAA) soaking solution is (1.6-2.0) ×10 ^-4 g/L, ③The concentration of brassinosteroid (BR) soaking solution is (4.5-5) ×10 ^-4 g/L, Choose one of the three soaking solutions; (3) Determination of the weight ratio between the amount of soaking liquid and the air-dried seeds: soaking liquid: seed = 100ml: (50-100) g; (4) Soaking: Submerge the seeds in the soaking solution and soak for 18-30 hours in the dark at a temperature of 23±2°C, stirring during the period to ensure the uniformity of soaking of the seeds; (5) Sowing or re-drying: after soaking, the seeds can be sown immediately after soaking, or they can be re-dried for later use. When re-drying, take out the soaked seeds and spread them on paper towels or towels. ±2h, put it in a refrigerator at 4°C for storage until use.