Study On Gene Sh₂ Identification And The Heredity Of Main Qualitative Traits In Super Sweet Corn

With eight inbred lines of super sweet corn according to the Griffing diallel methodⅡdesigned experiment and hybrid combination. First, specific primer was designed and the genes of inbred lines determined; Secondly, to aim the weakness of super sweet corn breeding at present, such as bad taste, bad tenderness and low sugar content. Alteration disciplinarian and genetic characteristic of fructose,starch,dietary fiber were studied. The main results as following:1. According to the reported sequence, specific primers were designed and the genes of inbred lines were tested. The result was showed that eight inbred lines were controlled by the gene sh2.2. The fructose content of most inbred lines and hybrid combinations reached the maximum in 14 days after pollination,and very small number of inbred lines and hybrid combinations reached the maximum in 14 days after pollination. It decreased gradually, with the number of days after pollination increasing.3. The starch content of inbred lines and hybrid combinations,14～17 days after pollination, will continue to increase and the rate of change was faster, and 17～20 days after pollination, there will be changes in rates of sustained growth, but slower growth.The starch content of most the inbred lines and hybrid combinations reached the maximum or higher maximum value in 20～26 days after pollination.4. The insoluble dietary fiber content of inbred lines and hybrid combinations grows basically with the days of pollination increased, and the highest insoluble dietary fiber content of a very small number of inbred and hybrid combinations appeared in the 20 days after pollination, or the 23 days. The highest content of soluble dietary fiberof inbred lines appeared in 20 days after pollination,and the highest content of soluble dietary fiber of hybrid combinations almostly appeared in 17 days after pollination. The soluble dietary fiber content of inbred lines and hybrid combinations reached the maximum and then declined with the days of pollination increasing.5. From the synthetic evaluation about the value of general combining ability, the results showed that T-4 was refreshing and with the advantage of moderate fructose; secondly, T-14 was a better inbred line with the advantages of higher fructose content and lower starch content; T-5was a better inbred and the best parent for breeding of good flavor and taste,and with the advantages of lower starch content and lower insoluble dietary fiber content.6. The result showed that there was not directly correlation between hybrid combinations SCA and GCA of parents,the analysis of total combining ability showed that the combinations decided by TCA,was not simply judged by GCA or SCA. The results showed that T-4×T-8 and T-14×T-3 were very refreshing and with the adventage of high fructose content; T-14×T-5 was very crisp and with the adventage of high fructose content. T-1×T-5 was refreshing and very crisp. But it was difficult to collocate the very refreshing,very crisp and high fructose content hybrid combinations.7. According to the calculating of heritability of 4 traits.The order of the generalized heritability of all traits showed as following:insoluble dietary fiber>starch>soluble dietary fiber>fructose; The order of the narrow heritability of all traits showed as following:fructose >starch>soluble dietary fiber>insoluble dietary fiber.8. Fructose was more prominent than other 3 traits in the Over-HP heterosis, Over-MP heterosis, Over-LP heterosis. Starch showned Over-LP heterosis prominently; Insoluble dietary fiber showned negative Over-HP heterosis partly; Soluble dietary fiber showned Over-LP heterosis partly.