Study On Different Methods For Dividing Hererotic Groups In Wheat

To reveal the heterosis of groups from different parents,45combinations（F1） weremade from10wheat parents based on the method of incomplete diallel. In this study,heterosis and combining ability of8traits in F1generations were analyzed. Apart from that,heterotic groups were divided from10wheat varieties using SRAP markers. In order to selectcombinations with strong heterosis, enlarge the germplasm resources for making groupsperforming strong heterosis and expand the genetic foundation of hybrid wheat, pedigree andSRAP markers were combined to divide heterosis groups from106wheat varieties inHuang-Huai region. The results were as followed:1. Heterosis is widespread in F1.Investigation of eight agronomic traits showed positiveheterosis (except main spike spikelet),and significant difference between different traits.Theorder of mid-parent heterosis performance of8traits is as followed: yield per plant>InternodeLength below ear>effective tiller>plant height>1000-grain weight>ear length>main spike spi-kelet.2. Analysis of combining ability showed: GCA are very different whether different traitsfrom the same parent, or the same traits from different parents. General combining ability andspecific combining ability are not necessarily linked. The performance of the F1is closelyassociated with a series of factors, includind parental GCA, SCA of cross, with parentalperformance as well as environmental conditions. In order to obtain a higher yield heterosis,parents selected should have no obvious defects and higer yield component traits GCAwhich could complement each other.3. Based on performance of8agronomic traits,10parents were divided into five categories. Additionallly,10parents were divided into five categories by GCA value of parental agronomic traits.Then,10parents were divided into four categories using SRAP markers when genetic similarity coefficient was0.72.4.47SRAP primers were used to study106wheat varieties in Huang-Huai region.Therewere314specific bands, which amount to27.62%of total bands(1137) of those primers.Genetic similarity coefficient between varieties and cluster analysis were done based on SRAP markers. Those varieties could be divided into14,9and5heterosis groups whengenetic similarity coefficient was0.635,0.615and0.575respectively.5. Comparing heterosis groups divided by Clustering results of SRAP markers andpedigree method showed that the differences were significant when the similarity coefficientwas large, but with lower similarity coefficient, differences were getting less and lesssignificant. Therefore, to some extent, results from the two methods in dividing hybrid groupswere consistent.6. Comparison with different methods to divide heterosis groups in wheat showed SRAPmaker assistant method was more accurate and convenient.7. Dividing heterosis groups by SRAP markers and pedigree showed that SRAP markersmethod was more clear, intuitive and effective.