| The seed germination is an important physiological process in the life cycle of plants. "Preharvest sprouting " is closely related with seeds germination, it refers to the phenomenon that the grain germinated in the ear encounter the rainy weather before harvest,this phenomenon especially is widespread in the cultivation and seeds production of hybrid rice in South China, and seriously affect the quality and the yield of hybrid rice seed. There have been many studies showed that phytohormone was one of the major factors that affect seeds germination, especially two kinds of phytohormone-GAs(gibberellins) and ABA(abscisic acid). Phytic acid(six phosphoric acid of inositol,IP6) as phosphorus storage body in plants,there are some studies have found that it has important effects on the germination and other physiological characteristics of seeds. This paper used parents of hybrid rice with closely growth period and obvious differences in the degree of difficulty of the germination as experimental material, comprehensively analyzed the internal relation with phytohormone,phytic acid metabolism and seeds germination, preliminarily studied the regulatory mechanism in the interaction between phytohormone and phytic acid on the germination of rice seeds. On this basis, I studied the chemical control method of rice seed germination by the way of exogenous addition, which has great realistic significance in effectively solving the problem of preharvest sprouting and improving the yield and the quality of hybrid rice. The main results were as follows:1.The relationship between phytohormone and the germination of rice seeds: IAA(indole-3-acetic acid) and GA1 contents were increased during the germination of rice seeds, and the content of endogenous IAA, GA1 in easy germinated seed was higher than in the hard germinated seed. The content of ABA was decreased, and the endogenous ABA contents in easy germinated seeds were lower than in the hard germinated seeds with different periods. Statistical analysis showed that, the relation between ABA contents and seeds germination exists significant negative correlation.2.The relationship between phytic acid and rice seed germination:On the whole, phytic acid contents were decreased during the germination of rice seed, the contents of decomposition and synthesis of phytic acid in easy germinated seed were higher than in hard germinated seed. Inositol contents were increased during the germination of rice seed,the synthetic quantity and the rate of synthesis in easy germinated seed were also greater than in hard germinated seed. This shows that the efficiency of catabolism of storage material in easy germinated seed was higher than in hard germinated seed. Statistical analysis showed that:the relation between endogenous phytic acid contents and germination performance exists significant negative correlation in easy germinated seed-Jin23B.3.The influence of the interaction between phytohormone and phytic acid on the germination of rice seed:in the process of the seed germination, there was interaction between the main phytohormone ABA,GA1 and phytic acid. There is maximum degree in the relationship between ABA contents and phytic acid contents. Synergistic effect exists between phytic acid and ABA. There is mutual antagonism between phytic acid and GA1,.4.Regulation effects of exogenous growth substances on the germination of seeds: Application of ABA,phytic acid or ABA+phytic acid both inhibits the germination of rice seeds. Application of ABA or phytic acid inhibits the synthesis of GA1 in the process of the seed germination,but has a promoting effect in a short time; Application of ABA or phytic acid has effects on IAA contents. Combined with experimental conclusion of rice seed germination:the inhibitory effect of exogenous growth substances on the seed germination-ABA+phytic acid> ABA> phytic acid. |
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