| In order to elucidate the senescence of Yumai 66 with large-spike type during the grain filling stage,Xiaoyan 22 was taken as the comparison to study the senescence and nitrogen metabolism of the two varieties.The results showed that large green leaf area could be observed in Yumai 66.The MDA content in the leaves increased slower than that of Xiaoyan 22.The nitrogen content is higher in leaves,stems and kernels than that of Xiaoyan 22.The nitrogen transporting rate is higher before anthesis.The contribution rate is lower before anthesis,but higher after anthesis.Therefore,the higher nitrogen content in Yumai 66 in the late grain filling stage guaranteed the higher photosynthesis and enhanced the grain yield. |