تعیین بهترین شاخص¬های گزینشی برای تسهیل عمل انتخاب در برنج

In order to determine superior F3 families in 260 families derived from cross between Tarom Mahalli × Khazar using of base and optimum selection indices, an experiment was conducted at research field of Gonbad High Education Center in 2008. For this purpose 260 F3 families with F1 and parents were cultivated. To obtain the best selection indices, various vectors of economic values consisting of phenotypic and genotypic correlation, path analysis and heritabilities were took into consideration. Positive and significant phenotypic correlation was detected between yield and panicle number (0.836^**), plant height (0.409^**), panicle exertion (0.476^**), filled grain (0.698^**) and biomass (0.958^**). The result of regression analysis showed that panicle number, filled grain and biomass explained the high level of phenotypic variation related to yield respectively. Also result of path coefficient analysis showed the importance of panicle number, filled grain and biomass in yield variation. Between calculated selection indices, 8^th selection index (obtained from the heretabilites of first order traits) and 6^th selection index (obtained from the genetic direct effects of first order traits and significant genetic correlation coefficients of other traits with grain yield per plant) showed high relative efficiency particularly for base index with more relative efficiency and genetic advance for grain yield in comparison with other calculated indices. According to these results the superior F3 families of Tarom Mahalli ×Khazar with the best genetic advance could be selected by using of base and optimum selection indices.