برآورد ترکیب‌پذیری و اثر ژن برای تراکم دانه در برنج (Oryza sativa L.)

Five rice genotypes (Hasseni, Dailamani, Shastak-mohammadi, Sange-tarom and Daei-shastak) and their 10 hybrids obtained through half diallel set were evaluated for combining ability and gene effect studies of grain density trait. Single seedlings of each entries were transplanted at 20×20 cm spacing in 3×5 plots in a randomized block design replicated three times during 2004-2005 at research station of Agricultural Sciences and Natural Resources University General combining ability (GCA) and specific combining ability (SCA) was analyzed for this agronomic trait. The results showed significant difference between general (GCA) and specific combining ability (SCA) for the investigated character. This indicates the role of additive and non-additive gene action in inheritance of the trait. Also the results showed that selection for grain density character can’t well succeed, because of there was a high amount of non-additive gene action in the genetic variance. Thus this character was important for production of hybrid variety and application of heterosis. In this study, investigation of graphic Wr-Vr analysis for grain density indicated overdominance effect because the regression line intercepted the Wr axis at negative point (a = -118/024). Also, the GCA effects of each parent for this trait showed that the Daei-shastak is good general combiner for grain density.