Innovation And Apolegamy Of The Superior Cross Combination Of Silkworm Sex-linked Balanced Lethal System Resource

Content:The Abundant breeding material and mature breeding methods are the key and foundation of breeding improved varieties. In this thesis, utilizing sex-linked balanced lethal lines sd2, px2 introduced and ordinary silkworm lines Y8, HY preserved as the parent material, using the breeding method of hybrid, backcross and test cross, and marker assisted selection, we carried out the researches in the innovation of the sex-linked lethal balance resources, in the determination analysis of combining ability, the parents screening and matching of dominant hybrid combination, and in the economic trait testing of candidate hybrid combinations and so on. we also explored the innovation and utilization of the sex-linked lethal balance resources, laying a good germplasm and technology base for breeding male silkworm effectively and fast with a high rate of male silkworm and good economic traits. It is very important for achieving the aim of special-raising male silkworm and promoting the sustainable development of sericulture. This paper has made the major findings as following:1. New sex-linked balanced lethal system material YH4, YH8, YH12 and YH18 are gained by using male-female successive backcrossing or congestive backcross, and fixed their characters further. The rearing result showed that there were some difference between new sex-linked balanced lethal line from two breeding methods due to different parents. In contrast, the characteristics of the new sex-linked balanced lethal lines gained by male and female backcross method are closer to its backcross parent. Therefore, in effect, it is prefer to choose the male and female backcross method.2. Using the model of incomplete diallel, the characters compare and analysis of combining ability of hybrid combinations, which matching new-building and introduced sex-linked lethal balance lines as male parents and fine conventional varieties as female parents, have been done. The results showed the male silkworm rate of each hybrid combination of all combinations reached 97.83% or more, further verified that the two kinds of ways creativing sex-linked balanced lethal lines resources are feasible and effective.There are significant differences by analysis of variance between different combinations in economic traits and combining ability, indicating that it was very significant of the impact for hybrid Fl gained by matching three female parents and six male female parents. Based on estimate of the effect value of the combining ability, two dominant hybrid combination of male silkworm MC×sd2, MC x YH18 have been matched by selected the female parent MC and male parents sd2 and YH18 with higher expectations.3.The new candidate combination MC x sd2, MC x YH18 have been tested, selecting the spring variety Jingsong x Haoyue as control. The results showed that the new male silkworm varieties MC×sd2, MC x YH18 displayed high male silkworm rate, good health care, high cocoon and silk yield, and quality silk, with a strong performance.Using the methods of male and female backcross and congestive backcross to create the new sex-linked lethal balance lines resources of silkworm can be enriched effectively the breeding material of male silkworm varieties. Based on the determination analysis of combining ability, the breeding parents meeting the requirements can be screened from the range of parents, this is conducive to breeding good male silkworm varieties rapidly and efficiently.