Abstract
Diallel analysis of the resistance to sheath blight was performed using 5×5 reciprocal crosses of lines belonging to the grain type by a field inoculation test to clarify the inheritance of the resistance to sheath blight. The mean additive effect, mean dominance and remaining dominance appearing in a specific combination were significant for relative lesion height : RLH at the 1% level of probability. The results of the analysis for RLH could fit the additive and dominant model without epistasis effect. The heritability was high in a narrow (0.773) and broad sense (0.935). Additive effect for height of lesion on the sheath : HL was significant at the 1% level, while the dominant effect was not. The results of the analysis for the height of flag leaf : HF did not fit the additive and dominant model. There was a significant correlation between the average RLH of better resistant and mid parent ((BP+MP)/2) and that of the hybrids (r=0.942, p<0.001). The additive effect was stronger than dominant effect for RLH. Therefore, the selection for RLH in early generation is effective to develop inbred lines rapidly.
