Eighteen cross combinations of mid-season hybrid rice were grown with 2 densities and 2 N rates to study the relationship between grain plumpness and the sink-source structure.

The grain plumpness under two cultivated methods (t he system of rice intensification and traditional cultivation) was investigated using 18 mid-season hybrid rice combinations.

The grain plumpness and its relationship with grain yield traits of different new rice varieties were studied according to the classification of brown rice thickness.

Study on Grain-filling Rate of Intersubspecific Hybrid Combination 5460S/Guang Kang Geng No2;

The results showed that the filled grain presented differences among grain-filling rates which can be dissected to different groups,such as >1.

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).

Although N application of spikelet promoting,spikelet sustaining or redundant fertilization would result in high grain plumpness, the size of hull was reduced, so that grain weight were also dropped.

Grain plumpness decreased by low temperature treatment during booting and grain filling period, and the visible effect of grain plumpness were founded from sixteen to twenty days after heading.