氮素营养水平对棉花不同部位叶片衰老的生理效应

通过3个氮素(N)水平(低氮0.kg/hm2、中氮189.50.kg/hm2、高氮395.0.kg/hm2)处理,研究棉花主茎功能叶和不同部位果枝叶衰老过程中的生理生化变化特征。以转基因抗虫棉33B为材料,采用随机区组设计,研究棉花生育期内不同施氮水平下棉花叶面积指数和叶片(主茎功能叶和果枝叶)生理指标(叶绿素含量、可溶性蛋白质含量和丙二醛含量)的差异,分析氮素影响不同部位叶片衰老的效应。结果表明:1)在本试验条件下,盛铃末期为各指标变化的转折点,表明这个时期是叶片生理功能衰老的起始期;2)氮素营养缺乏会引起整体叶片的叶绿素、可溶性蛋白质含量大幅度下降,丙二醛含量升高,加速了叶片的衰老进程;3)当氮素过多时,会加速下部叶片的衰老,上部果枝叶对氮素的缺乏最敏感,因此,施入适量的氮肥,可获得延缓整株叶片衰老的效果。

Physiological effects of nitrogen nutrition on the senescence of cotton leaves at different positions

This study evaluated the physiological effects and biochemical characteristics of functional axial leaf and different position sympodial leaf as affected by applying different levels of nitrogen fertilizer(0 kg/ha Low N;189.50 kg/ha Middle N;395.0kg/ha High N) using Bt-transgenic hybrid cotton variety 33B.The differences of leaf area index and leaf physiological index(chlorophyll,dissoluble protein and MDA) were studied with different levels of nitrogen across the growing season were studied using a randomized block design.The leaves were divided into four classes according to their positions: stem leaves,top sympodial leaves,middle sympodial leaves,lower sympodial leaves.The main results were as follow:(1) Under the conditions of this experiment,full boll stage was the turning point of every index,indicating that this was the starting phase of leaf senescence;(2) The content of chlorophyll and dissoluble protein of the leaf decreased significantly and MDA content increased when nitrogen was deficient,which accelerated the process of senescence;(3) Compared with normal level of nitrogen,excessive nitrogen would increase senescence rate of lower sympodial leaves and aggravate the trend of senescence for the whole plant.The top sympodial leaves were most sensitive to nitrogen deficiency.Therefore,proper nitrogen applications would delay cotton leaf senescence.