Application Of Four Plant Growth Regulators In Hybrid Rice (Oryza Sativa L.) Seed Production And Multiplication

Heterosis is a universal phenomenon in the living nature. Utilization of heterosis is one of notable achievements to improve crop yields and quality in modern agricultural Science & Technology, and the hybrid seed production and multiplication is the most key step in heterosis utilization introduced into crop production. Plant growth regulators have wide application and have markedly increased in yield and quality in seed production and multiplication of hybrid rice. Using WA types (wild-abortion type) Zhen-Shan 97A, Wei20A, DA types Xieqingcao A, YinNinShuiTianGuoXing II -32A, Thermo-sensitivity sterile type PeiAi 64S and their corresponding maintainer lines as CMS line breeding materials, MingHui63 type as restorer line, the application of four plant growth regulators on seed multiplication of sterile lines and seed production in hybrid rice were studied in this paper. The results were as follows:1. Using different dose of GA3 conduced a significant effect on yield and seed quality during tassel stage of sterile line in seed production and multiplication of hybrid rice. The seed setting percentage and output enhanced with the increased treatments of GAs and arrived at the top value at a certain dose. Results revealed that the peak value was various among different sterile lines. ZhenShan97A and XieQinCaoA were 180g/hm2, Wei20A was 225g/hm2, II32A was 315 g/hm2, while AiPei64S reached its top value at 675g/hm2. Over this dose, the seed setting percentage and yield would decrease instead. It is obtained that the weight per 1000 grains has opposite linear correlation with the dose of GA3. Spraying GA3 during tassel stage of sterile line helped to increase the endogenesis GA3 content, a-amylase activity and reduce ABAcontents in seeds. The results showed that not only the seed germination was increased significantly but also the seed establishment was evidently unproved before harvest, which led to the decline of seed storability. The larger dosage of GA3 used, the more evident decline range was showed. The study indicated that using high dosage of GAi in order to increase hybrid rice seed production and multiplication is one of the leading causes to make the worse quality of the hybrid rice seeds in sowing.2. ZhiZhongLe (its old name is "902" synergist) is a kind of compound plant growth regulators without GA3 ingredient. It helped plants to absorb exogenous GA3 and enhance cooperative roles among hormones, which can decreased the dose of GA3 used the field about 50% and reduce the cost of hybrid seed production. Furthermore, the ZhiZhongeLe can move up the flowering period by 30 min, and increased the outcrossing rate, which will increase the yields of seed production and multiplication by 10%, while spike germination were abated (decreased by 20%). The seed storability and sow traits were obviously unproved. It is concluded that ZhiZhongLe helps to increase yields, improve comprehensive advantages of seed characters as well.3. According to the inheritance effect and performance characteristics of spike germination during the seed production of hybrid rice. Reasonable using of exogenous inhibitors was an effective method to control spike germination and improve seed sowing quality. "Spike Germination Inhibitor" (IS) is a type of compound plant growth regulators made up with 30% maleic hydrazide and 60% inhibit organic acids. Spraying 1800 g/hm2 (effective concentration was 1000ug/g) during the period from the end of milking stage to the beginning of maturing stage of inbred line can effectively restrain spike germination of hybrid rice seed production and multiplication, without bad effects on external property of sterile lines. The germinating power of harvested seeds can restore to normal in two months. According to field experiment data and chemical biochemical analysis, it came to the conclusion that the action mechanism of spike germination inhibitors restrain the seed advance germination on the whole dues to the elimination or resistance the physiological indu...