Study On Combination Screening Method In Breeding Restorer Lines For 6311S

The general method of breeding new restorer lines is to select from two restorer lines cross descendants by phenotypic characters in early generations and by Combining ability in late generations. The effect was not satisfying, because phenotypic selection and combining ability selection can not fit well, sometimes the results were opposite , if phenotypic selection was strict in early generation, materials with good combining ability would be lost earlier; but if the criterion of phenotypic selection was wide, the workload both in early and late generations would be very large. Combination screening method in breeding restorer lines for 6311S was studied according to gamete selection in maize breeding. 26 F1 were derived from 8 restorer lines by Griffing IV design, then 26 triple cross hybrids were obtained from 26 FI and 6311S. Important characters of single cross hybrids and triple cross hybrids.combing abilities of 8 restorer lines and 26 single cross hybrids were analyzed. Meanwhile, the correlations between combing abilities and yields of single cross hybrids and triple cross hybrids were studied. The results were as follows:1. 5 FI were selected from 26 FI based on important characters of triple cross hybrids. They were Yul8/MianHui725, MianHui 725/9311, 9311/Zi66, MianHui725/Zi66, Ce253/CDR22, from which the probability of breeding new restorer lines for 6311S might be high.2. According to phenotypic characters of single cross hybrids. 9965/ZJ66. 9311/CDR22, 351/Zi66,Yul8/Zi66,Ce253/CDR22,351/9311 were chosen. Phenotypic selection and combing ability selection got different results.3. 351. 9311, Zi66 and CDR22 had good GCAs; Ce253/CDR22. 9311/CDR22. 9965/Zi66, 351/Mianhui725 and 9965/Yul8 had good SCAs in yields.The non additive variation was principal for spikelets per panicle , filled spikelets per panicle, seed setting rate, and grain weight per plant of single cross hybrids: while the additive variation was greater for only 1000-grain weight. Among 6 FI selected by phenotypic selection, GCAs play more important role in the yield of 351/Z166. But SCAs play more important roles in the yields of the rest.4. SCAs of 5 F1 selected by combining selection were different, among the restorer lines of 4 hybrids, at least one had high GCA . but the correlations between parents' GCAs and triple cross hybrids' yields were not found.5. These results suggest that Combing ability selection in early generation might be a quick and effective method of breeding restorer lines.