Genetic Dissection of Some Important Agronomic Characters in Rice Using Line × Tester Analysis

To determine the genetic structure, general and specific combining ability of some important agronomic characters, eight rice cultivars including 5 lines and 3 testers were crossed in Rice Research Institute of Iran (RRII), at Rasht, in 2000. Parental lines and F1 were planted in a Randomized Complete Block Design with three replications in the year 2001. Eleven important agronomic traits including yield and its components were recorded. Analysis of variances based on line×tester method showed that the mean squares for all traits were significant at 1% level. General combining ability (GCA) was positive and significant for grain yield in Khazar and Salary. Kanto and Salari have showed a negative and significant GCA for fertile tillers, as one of the most important yield components. Lines 213, 229 and Domsiah had negative and significant GCA for days to 50% of flowering. The lines with positive GCA can inherit those characters to progenies positively. While the lines with negative GCA can negatively transfer those characters to progenies. Estimation of components of genetic variance indicated that the number of fill grain per panicle and days to 50% of flowering were controlled by additive gene effects. It indicated that these traits can be transferred into progenies. For traits such as grain yield, fertile tillers and length of flag dominant gene effects was predominant.