Abstract: It was discovered from studies on 66 varieties in 3 successive years that among these varieties the variance was not significant in the number of first panicle branches and the number of seeds,but the variance was significant in the number of secondary panicle branches,though the number of seeds was rather stable.The seed number per ear was closely correlated with the first and secondary panicle branches.The secondary branches were responsible for the increase of seed number per ear and the percentage of sterile grain as well.The first branches had some repressive effects on the sterile grain rate.The sterile grain percentage of an ear was related with the number of secondary branches,and the hereditary characters of the variety.Owing to two sections of filling phenomena in the secondary branches,it may lead to a higher sterile grain rate.if some unfavorable factors happen.To a certain extent,in order to increase the total number of grains per aeit area,increasing ears per mu and keeping a higher seed-setting rate are important in high-yield rice cultivation in a vast area.Hence,the ear type of more seeds on the first panicle branches and fewer sterile seeds on the secondary branches can be used as a morphological characteristic index in selecting high yield varieties by rice breeders.

Key words: Rice ear, First panicle branch, Secondary panicle branch, Seed setting, Filling