水稻氮素供需差与不同叶位叶片氮转运和衰老的关系

 采用去穗和疏花方法调节稻穗氮需求量 ,研究了水稻氮素供需差 (NSDB)对不同叶位叶片氮转运和衰老的影响。结果表明 ,在NSDB <0的条件下 (对照 ) ,植株上部 4张叶输出氮素 ,叶片正常衰老 ;随NSDB提高 ,顶部叶片尤其是顶 4叶的氮素输出显著减少 ,叶片MDA含量下降 ,SOD和CAT酶活力提高 ,上位叶与下位叶之间的叶色差缩小 ;当NSDB >0以后 (去穗 ) ,上部 4叶的氮积累量不仅未减少 ,相反还有显著的增加 ,叶片的衰老进程被延缓。研究证实顶 4叶叶色受氮素供需差的影响最大 ,当土壤供氮不能满足库需氮时 ,顶 4叶叶色浅于顶 3叶

Relationships Between Balance of Nitrogen Supply-demand and Nitrogen Translocation and Senescence of Leaves at Different Positions of Rice

By removing panicles and spikelets, the effects of nitrogen supply-demand balance (NSDB) on nitrogen translocation and senescence of leaves at different positions of rice plant were studied. The results showed that under NSDB<0 (CK), nitrogen translocation and senescence of the top 4 leaves was normal. With the increase of NSDB, exported nitrogen from the top leaves especially the fourth leaf from the top (LFT) decreased remarkably. Thus, their MDA contents and differences in color (SPAD value) decreased, while the activities of SOD and CAT increased. Under NSDB>0 (panicle removal), N accumulation of the top 4 leaves increased significantly, and the leaf senescence process was delay. The results also indicated that the color of the fourth LFT was mainly affected by NSDB among the top 4 leaves and was lighter than the third LFT when nitrogen supply was insufficient for the need.