With two-line hybrid rice Yangliangyou 6 and Liangyoupeijiu and three-line hybrid rice Shanyou 63 as materials, the relationships of source, sink and flow with grain filling were studied.

Progress on research of rice population was summarized, which includes yield production,grain filling,source sink characteristic and optimizing control on rice population.

With two typical Japonica/Indica hybrid rices PC311×Zaoxiandang 18 (poor grain plumpness) and Ce 03×Yangdao4 (good grain plumpness) as materials,the relationship between the grain sink activity and its grain filling was studied.

Characteristics of Carbohydrate Transfer of Stem and Sheath and Grain-filling in Two-line Hybrid Rice;

Characteristics of the vascular bundles in the panicle and their relations to the grain-filling for the different panicle types of rice;

The results showed that the contents of endogenous endosperm Put,Spd and Spm in grain of three uppermost panicle branches is obviously higher than that in three lowermost panicle branches during the beginning stage of grain-filling,and line with heavier grain-weight is higher than that in the lighter one,especially for the Spd and Spm.

The restriction of two-line hybide rice development is low grain plumpness,which is decided by supplying power of source,transport power of flow,acceptant power and compatibility of store and temperature.

Five rice lines (varieties) with different genetic differentiation were crossed with eight indica cultivars for comparing and analyzing the grain plumpness among their hybrids.

The genetic analysis was made on grain plumpness of hybrids in indica japonica lines(IJLs) with different genetic differentiation mated with indica photo thermo sensitive male genetic sterile lines (PTMGS).