Screening Marker Genotypes Of Elite Combining Ability For Panicle Length And Branch Number Traits In Parents Of Hybrid Japonica Rice (Oryza Sativa L)

At the beginning of1990’s, hybrid rice was initially planted in the areas adjacent to China in Viet Nam, and got great successful. Since then, officers in departments of agriculture in Vietnam encouraged farmers to grow hybrid rice as long as the conditions permit. The grain yield of hybrid rice was6-6.3t/ha,1.81t/ha higher than that of conventional cultivar averagely. In recent years, the areas of hybrid rice planting in Viet Nam increased continuously, and reached0.7million hectares in2009, occupying ten percent of the total rice area. Several hybrid rice cultivars with short growth duration such as TH3-3, VL20, HYT100, TH5-5and LC25, were planted in a large scale in Northern Viet Nam. However, with the development of industrialization and modernization in Viet Nam, the area of arable land is decreasing dramatically, and agriculture faces new challenges. Developing hybrid rice further is one of the effective ways to guarantee the safety of food in Viet Nam.In order to improve combining ability of parent lines of hybrid rice more efficiently, SSR marker genotypes of elite combining ability for three panicle traits were screened in this study, by analyzing the data of combining ability and SSR markers in six CMS lines and twelve restorer lines. The6CMS lines and12restorer lines were genotyped using115pairs of SSR primers. Combining ability of the18parental lines was analyzed for the3traits, namely, panicle length, first branch number and second branch number using the data of72Fis made with North Carolina II genetic mating design. The results were the follows.1. The6CMS lines and12restorer lines were genotyped using115pairs of SSR primers. A total of153alleles were detected at fifty-nine SSR polymorphic loci. The rate of polymorphic loci detected was51.3%, and the number of alleles per marker locus ranged from two to five, with an average of2.59.2. According to the overall rank of GCA effects and VSCA for the3traits, BT-863A was the best among the6CMS lines, and R254and C418were excellent restorers, and77302-1was the best among the12restorers.3. A total of23SSR marker genotypes were detected significantly associated with combining ability of the3panicle traits. Among them,15marker genotypes were significantly associated with only one trait, seven marker genotypes with two traits, and one marker genotypes with three traits. Marker genotypes RM8254-120/180had positive effects for combining ability of all the3traits, and increased trait value of F1by21.63%for panicle length,21.12%for first branch number and16.12%for second branch number. Among the7marker genotypes associated with combining ability of two traits,6marker genotypes had positive effects for combining ability of parents. The other one had negative effect. Those marker genotypes with increasing effect could be directly used to improve combining ability of parents through the marker-assistant selection.