Evaluation of combining ability of local and improved rice varieties using line×tester analysis

Line × tester analysis is one of the biometrical methods for genetic analysis of quantitative traits to determine combining ability of the parents and heritability of the traits and identify the best breeding method for the studied population. In this study, three rice cultivars Hashemi, Nemat and Jelodar as the parental lines with two cultivars Sange-Jo and Deylamani as the maternal lines (tester) were crossed. The progenies and their parents (a total of 11 treatments including five parents and six progenies) were studied in a randomized complete block design with four replications in next year and plant height, tiller number, panicle length, grain number per panicle, 1000-grain weight, grain yield, grain length, grain width and grain length to width ratio were measured. Analysis of variance showed significant differences among genotypes for all of the studied traits. Evaluation of general combining ability of the parents showed that Hashemi was the good general combiner for reduction of plant height, but it also had the significant and negative combining ability for yield components including tiller number, panicle length, grain number per panicle and 1000-grain weight which lead to reduction of progeny values. Nemat had the significant and positive combining ability for all of the studied traits and was the best general combiner for tiller number, grain number per panicle and grain length. Jelodar variety was also the best general combiner for increasing panicle length and 1000-grain weight as well as reduction of grain width. Investigation of the specific combining ability of the crosses indicated that except Nemat × Sange-Jo and Nemat × Deylamani which had the significant specific combining ability for increase and decrease grain length, respectively, specific combining ability of the other crosses was not significant. Evaluation of genetic variance components showed that the additive variance had important and main role in all of the studied traits, except for grain length which the proportion of non-additive variance was more than the additive variance. It seems that the hybrid production method could be better to improve grain length in the studied population, but for other traits the selection methods will be useful.