I. Reasons for low germination rate of hybrid rice
1. The physiological characteristics of hybrid rice
(1) Poor grain plumpness. The proportion of hybrid rice not full-filled grains is large, generally accounting for about 20%. When the hybrid rice is produced, the pollination time in the field is as long as 10-15 days. The first pollination and seed ripening, the grain fullness ratio is large, the germination potential when soaking seed germination is strong, the germination is fast and neat, and the rate of pod formation is high; the seed after pollination is often only yellow ripe when harvesting, the grain is not full, and germination Root buds vary in length. Especially in the early spring when the temperature is not high, many low-maturity seeds are weak and resistant to seedlings.
(2) There are many cracked seeds. The cracking seeds are mostly determined by the characteristics of the sterile line. Generally about 10-20%. When the seedlings are produced, they have different varieties of strong flowers and weak flowers. Strong seeds have stronger growth potential, better clot closure, slower absorption of water during seed soaking, and difficult invasion of pathogens; and seed hull closure caused by weak flowers. Poor, rapid absorption of water during soaking, susceptible to bacteria infection, endosperm nutrient easily extravasated, so that the seeds sticky, acid, germination rate decreased.
(3) There are many seeds on the bud. Usually accounts for 1-5%, and when severe, it can reach more than 10%. Due to the long pollination time (10-15 days) at the time of seed production, if there is a rainy weather in the ripening season, the humidity in the field is large, and the seeds in the bud are more. After germination by soaking the buds, even if they germinate, they will soon turn yellow and die, causing the seedling rate to decline.
2. Influence of production and storage process
(1) Relatively high levels of granules in grain smut cause a decrease in the germination rate. Due to the long parental pollination time of hybrid rice in the seed production process, the occurrence of smut was heavier, generally accounting for 5-10%. If the maternal pollination process encounters continuous rain, the incidence is heavier. Sometimes it reaches 10-20%. The smut pattern resembles fullness. In fact, the inside of the chaff is pathogenic "black powder". Not only does it fail to germinate, it also seriously affects the germination of other normal seeds, resulting in a lower germination rate.
(2) Due to the accumulation of microorganisms. In the current seed production process, the use of 92 is increasing, from the original 10 grams per acre to 25 grams per acre now, and a large number of 90% accumulation has destroyed the dormancy of mature seeds, resulting in seed spikes. The possibility of germination increases; at the same time, various biological agents are used to adjust the flowering period so as to achieve high yields. Therefore, a large amount of microorganisms remain on the seeds, and these microorganisms threaten the life of the seeds to varying degrees.
(3) Due to harvesting on rainy days. When it comes to rainy days, peasant households rush to harvest their seeds and eagerly rush to harvest them. Due to the lack of drying equipment, they often use wet bags or baskets for overnight storage, and wait for the second day to dry. In this way, it is easy for the seeds to be "burned" or "suffocated" and lost their vitality.
(4) The seeds are not dry. Due to the high price of hybrid rice seeds, if the time of production reduction or acquisition is late or the seeds are tense, many seed production households often do not completely dry and make the seed water high, so the seed germination rate will inevitably decrease with the extension of storage time. . At the same time, high-moisture seeds are more prone to pest damage than dried seeds and lose germination.
3, improper soaking and germination
(1) Soaking time is too long. Soaking for a long time, lack of oxygen and accumulation of harmful substances affect germination. Many farmers still use the old method to soak seeds for 2 days and 2 nights or even longer, and do not change the water and do not wash seeds. So long soaking will cause insufficient oxygen supply, and will produce a large number of harmful substances that affect seed germination, resulting in Rotten species.
(2) Improper germination. The optimum temperature for the germination of rice seeds is 30-35°C, but some farmers still use plastic woven bags or film bags to cover the seeds for warm germination in the sun. Also useful in woven bags, placed in the pot or coal stove to use the heat after germination, due to the vigorous breathing of hybrid seeds, resulting in more heat, a little negligence, failed to timely watering and turning seeds, it is easy to cause the temperature is too high "Burning buds."
Second, increase the germination rate of hybrid rice
1. Strengthen field management and increase the germination rate of rice seeds. In the hybrid rice production, disease-resistant varieties, in particular the sterile line resistant to rice smut, should be selected to strengthen the integrated control of rice smut, bacterial leaf blight, rice blast, and sheath blight. The amount of use of 9200 should be properly grasped, as long as it can achieve the purpose of lifting the CMS neck, and blind use and excessive use should be avoided. Seeds should be timely harvested, timely sun exposure, and seed moisture must be strictly controlled during the acquisition. Resolutely do not meet the standards of seed moisture, no acquisition, who will be responsible for the acquisition.
2, do not advocate sun drying before soaking. According to tests conducted by the relevant scientific research departments, the hybrid rice seed not only does not increase its viability, but also causes the seed germination rate to decrease. In particular, the seed germination rate of Chen seeds that have poor viability is greatly reduced. This is mainly due to the further loss of water after exposure to seeds, especially for the seedlings of lycopene and green husk. The breakdown of cell contents leads to a decrease in germination rate when soaked. Therefore, it is best not to sunse the hybrid rice seeds before soaking. On the contrary, the bag seeds should be unsealed a few days before soaking, so that the natural moisture-recovering moisture will be beneficial to the repair of the seed cell membrane, which will help increase the germination rate.
3, the conditions for soaking seed water selection. The use of fresh water to select seeds can be used to remove the unwashed green valleys, valleys, valleys, and smut valleys that float on the water surface. This can increase the germination rate of the seeds. If the seeds are used in a stressful year, they can be soaked separately. Germinate to make full use of seeds that can germinate. To eliminate old soaking and germination methods, soaking methods with daily immersion night dehydration or daily filtrate soaking and intermittent water change are adopted.
4. Hybrid rice should be coated. Due to the large number of seeds in the process of seed production in the field, the coating can effectively kill many pathogens that the seeds carry, reduce the infection of the germs to the embryos during germination, and increase the germination rate. At the same time, it can effectively prevent germination. Or reduce the incidence of bakanae disease, bacterial leaf blight, rice blast, and rice smut.
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