Analysis for Yield Components of Hybrid and Conventional Rice under Different Seedling Quantity in Northern China

The process of forming yield and their components of hybrid and conventional rice in Northern China were analyzed. The result shows that the major cause that the yield of hybrid rice is higher than that of conventional rice lied in big economic coefficient of hybrid in contrast to conventional rice, and the higher assimilate distribution rate to grain contributed mostly to the higher yield. The hybrid rice had more grains number and big kilo-grain weight, but the predominance of grains number come mainly from secondary branch, which resulted in the lower seed rate of rice and turned into the bottleneck of the yield of hybrid rice. In order to exert the advantage of heterosis, increasing photosynthesis and seed rate is necessary. The two kinds of rice have their own feasible planting mode, one-seedling rice was propitious to heightening the average panicle weight、 kilo-grains weight、 seed rate, and finally increase the yield, however, three-seedling rice was more fit for conventional rice. As a result, it was necessary to combining appropriate cultivars and reasonable planting in practice.