Comparison on Grain Filling Characters Between Hybrid and Conventional Rice in Northern China

Grain filling characters of hybrid and conventional rice cultivars from northern China were analyzed by Logistic equation. There existed very significant difference in grain filling parameters between the conventional and hybrid rice. The difference in grain filling duration would result in the discrepancy of grain weight in different varieties, and this was one of the main factors. It would be favorable to increase grain weight by enhancing initial rate of grain filling and prolonging grain filling duration. The discrepancy of grain weight among the same cultivar might result from the difference of grain filling rate. The assimilate distribution rate to the grain in hybrid rice remained higher than that of the conventional rice, which compensated the deficiency of assimilate during the later period of grain filling. It suggested that to maintain longer duration with high rate of grain filling would be helpful to obtain heavier grain weight.