Studies On The Combining Ability And Heritability For Main Traits Of Med-season Indica Hybrid Rice(Oryza Sativa L.)

Five indica cultivated male sterile(CMS)lines(H-1A,H-2A,H-3A,H-4A,H-5A)and eight indica restorer lines(H-1R,H-2R,H-3R,H-4R,H-5R,H-6R,H-7R,H-8R),newly developed by Chongqin BangHao seed limited company,were used as materials to generate 40 combinaitions using NCII mating design.The general combining ability and the specific combining ability and heritability of 12 yield-related traits were studied.Among the 40 combinaitions of new rice variety,30 of them were chosen to analysis the general combining ability and the special combining ability of 10 ricequality traits.The newly developed CMS lines and restorer lines were evaluated here in order to provide scientific support for future breeding of hybrid rice parents and combinations.1,Analyses of 12 yield-related traits.The results showed that the general combining ability and the special combining ability of the six traits(entire growth period,plant height,average panicle length,average panicle number,grain weight and grain length)were significantly different,indicating that the heritability of the six traits are together controlled by the additive effect the non-additive effect.The special combining force variance analysis showed that the differences of the special combining ability were significant in 10 traits except for the grain width and the grain length to width ratio,.suggesting the two traits of grain width and grain length and width were controlled by the additive effect.The genotype variance proportions of the general combining ability were higher than those of the special combining ability in the 9 traits except for panicle number,seed setting rate and weight per plant,indicating that the F1 yield-related traits of the parents used in this study were mainly affected by the additive effectThe 7 traits on number of grains per panicle,average panicle length,seed setting rate,1000-grain weight,grain length,grain width and grain length-width ratio were affected predominately by the restore lines,wheras the remaining 5 traits on entire growth period,plant height,average number of grains per panicle,average number of filled grains per panicle and individual weight were affected mainly by the CMS lines.The narrow heritabilities were more than 50%for the 7 traits of entire growth period,plant height,average panicle length,average number of grains per panicle,average number of filled grains per panicle,1000-grain weight andgrain length.These demonstrated that the seven traits had high heritability with less affection by environmental factors.The expected progeny of those 7 traits could be easily obtained by selecting the dominant parents.2,Analyses of 10 ricequality traits.It showed that the differences on the general combining ability and special combining ability were significant or extremely significant on five traits of brown rice rate,head rice rate,chalky grain rate,chalkiness degree and alkali spreading value,indicating that the inheritance of these five traits was influenced by both additive effect and non-additive effect.The special combining force variance analysis showed that the differences of the special combining ability were extremely significant in 9 traits except for transparency,indicating the transparency trait was mainly affected by the additive effect.According to genotype variance proportions of general combining ability,the additive effect was dominant in the eight rice-quality-related traits except for the two traits of milled rice and transparency.The eight traits of brown rice rate,milled rice rate,chalky grain rate,chalkiness degree,alkali spreading value,gel consistency,amylose content and protein content were affected mainly by the male sterile lines,wheras the two traits of head rice rate and transparency were influenced mainly by the restorer lines.These demonstrated that the seven traits had high heritability with less affection by environmental factors.The expected progeny of those 7 traits could be easily obtained by selecting the dominant parents.The narrow heritabilities were higher than 70%for the 5 traits of amylose content,alkali spreading value,brown rice rate,protein content and head rice rate,indicating that these traits were affected in a minority by the environmental factors.Selection of parental lines based on those traits will increase the likelihood of obtaining the desired offspring.3,Comprehesive evaluation of the 13 tested parents based on the general combining ability and special combining ability effect.,(1)Accoring to the analyses of the combining ability on yield-related traits,the male sterile line H-1A was prominentin 9 yield-related traits,especially in the three traits of spike length,average panicle number and average number of grains per panicle.The male sterile line H-4A showed better performance in seven yield-related traits,especially in the average number of grains per panicle,average number of filled grains per panicle and individual weight.The restorer lineH-4R showed better performance in 6 yield-related traits,especially in the average panicle length and the seed setting rate.The restorer line H-8R showed better performance in seven yield-related traits,especially in the traits of average panicle length,average number of grains per panicle,average number of filled grains per panicle and number of individualweight.(2)Based the analyses of the combining ability onrice quality traits,the results showed that the CMS lines of H-1A and H-2A were prominent in the five rice quality traits ofhead rice rate,chalky grain rate,chalkiness degree,transparency and gel consistency.The protein content of H-1A is higher as well.The restorer lines of H-2R,H-3R and H-4R showed better performaces in the 4 traits of head rice rate,chalky grain rate,chalkiness and transparency.The ability of H-2R in brown rice rate,H-3R in gel consistency and H-4R in alkali spreading valueweremost prominent.Overall,the results showed that the male sterile line of H-1A had a great utilization value in 'both yield-related traits and grain quality traits.The yield and the rice quality of H-4R were better than those of other tested parents.H-8R was relatively predominate in yield traits,so thatit is a good option for further exploition.