Studies on Dry Matter and Grain Production of F1 Hybrid Rice in China : I. Characteristics of dry matter production

[摘要] To clarify high yielding factor of F1 hybrid rice in China, characteristics of dry matter production was examined by means of growth analysis and canopy structural analysis with special reference to native varieties, old-improved (1960-1970) and new-improved (1970-) varieties, belonging to indica-type rice, in the Zhejiang State, China. The brown rice of the F1 hybrid rice showed about two times of the yield of native varieties and 1.1-1.5 times of old-and new-improved varieties. The high yield of the F1 hybrid rice was resulted from the increased biomass (total dry weight) than the harvest index. The remarkable biomass increase in the F1 hybrid rice was mainly due to the high CGR rather than its longer growth period as compared with other common rice varieties. The mean value of CGR for 30 days before heading stage in the F1 hybrid rice was 30 g/m2/day. This high CGR was supported by high LAI in the canopy than NAR. And the high LAI maintained during the whole growth period was due to favorable canopy structure having high plant height, and thick and heavy stems. The light extinction coefficient of the F1 hybrid rice at the heading stage was smaller than those of native and old-improved varieties. Distribution profile of the leaf in the F1 hybrid rice showed pylamidal type, namely, the distribution pattern of the leaf was equally large from the top to the under layer of the canopy. Leaf photosynthetic rates in the F1 hybrid rice were not significantly different from the other common rice varieties at four growing stages. It can be concluded from these results that high yield of the F1 hybrid rice was realized by the remarkable high biomass production based on high LAI and an ideal canopy structure favorable for intercepting light for the long growth period.

[学科分类] 农业科学（综合）

[关键词] Canopy structure;乾物生産速度;CGR;群落構造;F1 hybrid rice;個葉光合成速度;LAI;純同化率;Leaf photosynthetic rate;ハイブリッドライス;NAR;葉面積指数