How To Cultivate Strong Rice Seedlings

By Author: doris zhang
Total Articles: 76
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In rice production, in order to obtain high yield, in addition to correctly selecting varieties, cultivating strong seedlings is also the basis of high yield of rice. There are many phenomena of bad seeds and seedlings when we raise seedlings. How to cultivate strong seedlings is an important issue of great concern to agricultural technology extension departments and farmers.

According to our production test results in recent years, the standard of strong rice seedlings should have the following four points: first, strong roots and more roots, and 13 ~ 15 manual transplants. Cultivating strong seedlings is to cultivate roots. Only when there are many and developed roots can seedlings be strong. Second, the stem is strong. Third, the seedling age should reach 35 ~ 40 days, and it is appropriate to have 4 ~ 5 leaf stages. It is best to have tillers on the seedbed. Fourth, the seedlings should be uniform and neat, with a height of 13 ~ 17 cm, and there are no sick seedlings and overgrown seedlings.

There are several important technical links in cultivating strong seedlings: first, seeds should be treated before seedling ...
... cultivation; Second, buckle the shed in advance to improve the ground temperature; Third, timely sowing and sparse sowing to cultivate strong seedlings; Fourth, strengthen the temperature and humidity management of seedbed, reduce the occurrence of diseases and supplement fertilizer in time. These technical links should be linked. Any link that has a problem may cause the failure of the whole seedling raising.nft system

Seed treatment before seedling raising
1. Germination test. The seeds bought back should first be tested for germination. If the germination rate does not reach 85% of the national standard and can not be used as seeds, it is necessary to find a seller to return or replace them.
2. Seed drying. The main purpose of seed drying is to break the dormancy of seeds, improve the permeability and water absorption of seed coat, improve the activity of enzymes, promote the respiration of seeds and the transformation of organic substances in vivo, and improve the germination potential.
3. Seed selection. It is very important to cultivate strong seedlings and select seeds. Now most farmers use clean water to select seeds. Only shriveled seeds can be picked up with clean water, and semi-finished seeds can not be picked up. If semi-finished seeds are used to raise seedlings, the seedlings will be thin, weak and thin. When transplanting seedlings, there will be 0.5 ~ 1 leaf less than the seedlings raised with full seeds, and there are often no tillers on the seedling bed, The heading stage was 2 ~ 3 days later than that of full grain seeds. We suggest using salt water for seed selection. Using salt water for seed selection is to use 50kg water and 12kg crude salt. The specific gravity of salt water is 1.13. Salt water seed selection, the selected seeds have full grains, high maturity and strong seedlings. Salt water seed selection must be cleaned twice with clean water, otherwise it is easy to produce salt damage and affect the seedling emergence effect.
4. Seed soaking and disinfection. During seed soaking, the weight ratio of seed to water is 1:1.2. The water after seed soaking shall be more than 10cm higher than the rice seed. During seed soaking, the accumulated temperature shall reach 100 ℃ (subject to the water temperature). Soak the seeds indoors at room temperature for 5 ~ 6 days. If the water temperature is 15 ℃, it takes 7 days to soak the seeds. Disinfection is the most effective method to prevent cachexia. According to the types of disinfectants, it can be divided into seed soaking disinfection, seed dressing disinfection and coating disinfection.
5. Germination. Budding is to sprout quickly and evenly, and it is also a key technology for cultivating strong seedlings. Germination is to put the soaked seeds at 30 ~ 32 ℃ and break the chest and show white in 1 ~ 2 days. When about 85% of the seeds have broken breasts, the temperature should be reduced to about 25 ℃. When the buds grow to about 2mm, the seeds should be spread in a cool place to cool the buds for sowing. The standard of germination is that the buds are neat and short.

Preparation of seedbed before seedling raising
1. Selection of seedbed. The vegetable garden in front of and behind the house with no pollution, good drainage, loose and fertile soil, no application of dryland herbicides and less pollution shall be selected.
2. Buckle the shed early to improve the ground temperature. At present, most farmers use standardized seedling raising greenhouses. We advocate preparing seedling raising soil, driving piles and chiseling holes in the autumn of last year, so that the shed film can be put on early next spring (mid and late March), so as to promote soil thawing, improve ground temperature, ensure seeds to be sown on warm beds, and make seeds take root and sprout early.
3. Preparation of seedbed soil. Generally, we use 20% mountain bark soil, 70% dry land soil without herbicide, and 10% rotten farm fertilizer, and then fully mix them, screen them through 50 mesh, use nutritional regulator according to the instructions, and add diammonium phosphate appropriately, which can play the role of sprouting, but not in excess (add 25g / m2 and fully mix them with the screened soil, and acid regulation, fertilization and disinfection are required to be completed at one time). After mixing the seedbed soil, cover it with agricultural film for later use, and then select the dry field soil for screening for soil covering.
4. Make bed early. When the soil thaws for about 10cm, turn the seedbed to a depth of 5 ~ 10cm to make a bed, level it with a rake, fine it evenly, and then lay an isolation layer (most farmers now raise seedlings with an isolation layer, which can be a plastic floppy disk with holes or woven bags laid on the seedbed ground), and evenly sprinkle the prepared seedbed soil on the isolation layer, with a thickness of about 2cm, The bed surface shall be flat without impurities and dirt.
5. Pour through the subsoil layer. Watering the bottom of the seedling bed thoroughly before sowing is the key to a good seedling. Therefore, when watering the seedling bed, it must be watered through about 10cm of the dry soil layer, otherwise the seedling emergence effect will be seriously affected.

Timely sowing and sparse sowing to cultivate strong seedlings
1. Sowing time. The best sowing time in our county is April 5 ~ 20.
2. Sowing amount. Proper sowing rate is the key to the success of seedling raising. If the sowing is too thick, the seedlings are weak, the tillers are few, and the nutritional space occupied by the individual seedlings is small; With sparse sowing, the individual seedlings occupy a large nutritional space, have good light conditions, absorb more nutrients, and have tillers on the seedling bed. The suitable sowing rate in our county is 150 ~ 200g / m2 before April 10, 250 ~ 600g / m2 after April 15, and the seedling raising in isolation layer shall not exceed 300g / m2. Those with low germination rate should be sown more, and those with high germination rate should be sown less.
3. Earth covering. After sowing, cover the soil evenly and uniformly, cover the soil with a thickness of 0.5 ~ 1 cm, supplement the places with exposed seeds, cover the soil again, and then apply sealing agent. When the covering soil is more than 1cm thick, it will cause the white neck of seedlings to be too long, and it is easy to be injured during transportation and transplanting, resulting in slow seedling speed, thus affecting the growth of rice.
4. Film covering. After sowing seeds, cover the soil, apply sealing agent, and then cover a layer of plastic film. This film can increase temperature, moisturize and weed.

Seedbed management
Controlling the temperature and humidity of the seedbed and the occurrence of diseases, properly supplementing fertilizer and improving the quality of seedlings are the key technologies to improve strong seedlings.
1.Temperature management. Before the emergence of 2.5 leaves, the temperature in the shed shall be controlled below 30 ℃. After the seedlings grow to 2.5 leaves, the temperature in the shed shall be controlled below 25 ℃. During the growth of rice, it is generally high-temperature long leaves and low-temperature long roots. Therefore, the measures to promote root growth should be adhered to in temperature management, and the temperature should be strictly controlled. For example, when the external temperature exceeds 15 ℃, the seedling bed should be opened with a small air outlet for ventilation and seedling refining before agricultural work in the morning; With the increase of ambient temperature, the vent should be gradually increased to improve the quality of seedlings; One week before transplanting, the film was uncovered to refine seedlings to adapt to Honda's environment.
2.Water management. Water management is also a very important technology in the seedling raising process. If watering too often, it will not only affect the temperature of the seedling bed, but also easily cause the seedling to grow excessively and affect the root development (if the root development is not good, the seedling will not be strong). Therefore, the watering times shall be reduced as much as possible during the seedling raising period. It is required to water enough and thoroughly at one time. Whether it is necessary to water or not should be based on reality: before the sun comes out in the morning, go to the seedbed to observe the rice seedlings. If there are large water droplets on the rice leaf tip (the water droplets are not dew droplets, but the water spit out by the physiological function of the rice itself), it indicates that there is no water shortage and there is no need to water; If there are small drops of water on the rice leaf tip, and the seedlings wilt at noon and there are dry cracks on the ground, it is necessary to water once in the morning or evening.
3.Disease management. The diseases occurring in the seedling stage are cachexia and bacterial wilt. Cachexia is mainly controlled by seed disinfection. Bacterial wilt is mainly related to the pH value of the soil and the sowing amount. If the pH value is greater than 7 or the sowing is excessive (more than 300g / m2), bacterial wilt is easy to be obtained. If it is found that bacterial wilt seedlings should be controlled with chemicals in time. The best control period is from needle setting stage to 1.5 leaf stage.
4.Fertilization management. When the rice seedling grows to 2.5 leaves, it is also the off milk period. The nutrition of the seed itself can not meet the needs of its growth and development. It is necessary to supplement nutrients from the outside. At this time, potassium dihydrogen phosphate (or 25 g / m2 of ammonium hydrogen sulfate) should be applied in combination with watering. Marriage fertilizer can be applied 3 ~ 4 days before transplanting. 25 g / m2 of ammonium hydrogen sulfate can be applied in combination with marriage fertilizer, and net fertilizer on the seedbed should be sprayed on the seedbed to prevent leaf miner Rice water weevil. We should let the seedlings go down to the ground with fertilizer and medicine, so as to facilitate Honda's rapid rejuvenation, rapid tillering, and early growth and rapid development of rice.