Analyses Of Selecting Parents Of Source Hybrids Of Maize Recycled Lines And The Related Lines With SSR Molecular Markers

Both domestic and abroad maize breeding organizations all used single hybrid stock as original material to breed recycled inbred lines on a large scale, but there were few of the research reports about selecting parent lines of the single hybrid (source hybrid) from which the recycled lines were to be developed. This research investigated the effects of adopting the GCA (general combining ability) and SCA (specific combining ability) as indices to select parent lines of the source hybrids to breed recycled inbred lines.This research adopted four classes of parents of source hybrids. Every pair parents of source hybrids in the 1st class possessed high GCA, and SCA between them was moderate; Every pair parents of source hybrids in the 2nd class possessed moderate GCA, and SCA between them was moderate too; In the parents of source hybrids in the 3rd class, one possessed high GCA, another possessed moderate GCA, and SCA between them was high; In the parents of source hybrids in the 4th class, one possessed high GCA, another possessed moderate GCA,and SCA between them was very small. Crossed every pair parents in the four classes to get four class source hybrids, developed recycled lines from each class source hybrid to get four class recycled lines, totally got nine new recycled lines. And then put these nine new recycled lines and seven original parent inbred lines(parents of source hybrids) together, according to the complete diallel cross design of Griffing (1956)'s method 4, did 16X16 diallel crosses to get 120 hybrids. Did field experiment for these 120 hybrids with randomized complete block design(RCB), got the average yield per single plant in a plot, estimated the 16 inbred lines' GCA, 120 hybrids' SCA. By comparing GCA's differences of four class recycled lines, and by comparing GCA's differences between recycled lines and the original parent inbred lines, as well as by analyzing the results of acquiring high yield hybrids from four class recycled lines, the effects of four classes of parents of source hybrids to breed recycled lines were evaluated. The results of this research were as follow:The effects of four classes of parents of source hybrids to breed recycled lines were different. From the view of raising recycled lines' GCA, the effects of the 1st, the 3rd classes of parents of source hybrids to breed recycled lines distinctly exceeded the effects of the 2nd, the 4th classes of parents of source hybrids to breed recycled lines. When crossed with the inbred lines from other source, the effects of the 1st, the 3rd classes of parents of source hybrids to breed recycled lines distinctly exceeded the effects of the 2nd, the 4th classes of parents of source hybrids to breed recycled lines too. In spite of these results, from the view to get high yield hybrids, i. e., to acquire high yield SCA of hybrid with the material limited to this investigation, the recycled lines of the 1st, the 3rd classes should cross with the recycled lines of the 2nd, the 4th classes. Therefore it was still necessary to adopt the 2nd, the 4th classes of parents of source hybrids to breed recycled lines.Moreover, results of this research indicated that most developed recycled lines possessed distinctly higher GCA effect than those of the original parent inbred lines. Results of the cluster with UPGMA (Unweighted Pair-Group Method of Arithmetic Averaging) showed that most of the recycled lines were in the cluster of either of their parents.We did a SSR (Short sequence repeat) molecular marker experiment on above 16 inbred lines to explore the relationship between SSR markers and yield trait. In allusion to the problems of current QTL researches, i.e. the material adopted in related QTL researches was not suitable to study various interactions, and current QTL researches often treated that molecular marker type datum of an individual corresponding to its quantitative trait value, possibly led to these two kind data not matching because the former datum was discontinuous and the latter value was continuous, as well as because...