Partial diallel cross analysis of yield and its related characters in rice (Oryza sativa L.) under irrigated and rainfed situations

In partial diallel cross analysis involving 16 parents in rice (Oryza sativa L.), both dominant and additive gene actions were found to play important roles in character expression. In the set grown irrigated situation, 9 traits, and in the set grown under rainfed situation, 8 traits were found to be predominantly controlled by nonadditive gene actions. These included important traits like grain yield, tiller number/plant, and No. of fertile spikelets per panicle. Panicle length, grain length, plant height and spikelet density were primarily determined by additive gene actions. Although the relative magnitudes of estimates of additivity and dominance were considerably influenced by growing situations, the direction of change was variable for different traits. In spite of these variations, however, the parents identified to be good general combiners for different traits from two sets generally the same. Important among these were Roti for grain size, IR 52 for harvest index, and IR SO and IR 36 for tillers/plant.