Determining the Gene Action Type for Grain Yield and its Components using Generation Mean Analysis in Rice (Oryza sativa L.)

The study was conducted at the Rice Research Department Farm at the Agricultural Research Station in Sakha, Agricultural Research Center - Egypt through the period 2019 - 2022 for two rice hybrids. The study included five populations for each hybrid (P1, P2, F1, F2, and F3), which were tested for the grain yield characteristics and its components to magnitude of gene action using generation mean analysis. Two rice populations GZ9399 × IRRI 148 and Sakha 104 × IM 16 were used for this study. The results of the scaling tests indicated that the characteristics evaluated in two crosses were not well-suited for the additive-dominance model, indicating the possibility of epistasis in the characters' inheritance. The general mean for each trait was wide significant differences, therefore grain yield/plant of cross 2 (Sakha 104 × IM 16) logged highly significant positive gene action effects while cross 1 (GZ9399 × IRRI 148) recorded highly significant negative additive gene effects. However, 1000 grains weight recorded a highly significant positive gene action effects for cross 1, while cross 2 had highly significant negative additive gene effects. From phenotypic correlation coefficient, in both crosses, grain yield/plant were positively and highly-significant correlated with branches number/panicle, number of panicles/plant and number of spikelets /panicles. Grain yield/plant of cross 1, it was positively and highly-significant correlated with panicle length, panicle weight. While cross 2, it was positively and significantly correlated with panicle length and positively highly significantly correlated with fertility percentage and 1000 grains weight.