Yields of an F1 Hybrid and its Parental Rice Cultivars under Different Environmental Conditions.

Abstract

One of the F1 hybrids, which showed comparatively high yield (MURAI and KINOSHITA 1986), and its parental cultivars were grown under 8 environments involving different locations, fertilizer levels and planting densities. The F1 showed the highest yield of the three genotypes at most of the environments. Fertilizer level was a predominant environmental factor affecting yield. The regression coefficients by FINLAY and WILKINSON (1963) for the three genotypes were around 1.0. These regression coefficients were not significantly different with each other, indicating similar responses among the F1 and parents. The percentage of ripened grains of the F1 was the highest of the three genotypes, contributing to the heterosis in yield. Similar extent of heterosis was recognized in harvest index. In dry weight at heading, however, the value of the F1 was smaller than that of mid-parent at the most of the environments. Therefore, it is concluded that the high yield of the F1 depended on high dry matter production after heading and smooth grain filling.