Effects of Different Light Intensity after Heading Stage on Dry Matter Accumulation and Nitrogen Uptake and Distribution of Super Hybrid Rice

To elucidate the cause of instability of grain yield of super-hybrid,2 super-hybrid combinations,2 conventional hybrid combinations and 2 inbred cultivars were used in this study.The dynamics of dry matter accumulation and nitrogen nutrition uptake and distribution after full heading stage were investigated under different light intensity with two treatments: natural light and 70% shading.The results indicated that,under shading: ① The amount of dry matter accumulation was lower than that of other cultivars(combinations) with a significant decrease and the rate of dry matter amount of super-hybrid distributed to panicles was only 32.1%;② The total nitrogen contents in grain of super-hybrid was decreased by 33.9%,which is higher than that of conventional hybrid(19.8%) and inbred cultivars(26.9%),and the nitrogen harvest index of super hybrid was decreased by 12.3%;③ The grain yield was decreased by 53.1%,which is significantly lower than that of other cultivars.