冬小麦冠层氮素及硝酸还原酶活性的垂直分布

为了探讨冬小麦冠层不同层次氮素及NRA分布规律，解释冠层氮素垂直分布差异的内在原因，对两个籽粒蛋白质含量不同的冬小麦品种进行了研究。结果表明，冬小麦叶片含氮量沿冠层垂直分布呈明显的梯度，自冠层顶部向下逯层降低。不同品种间存在差异，籽粒蛋白含量高的中优9507上部层次梯度大于籽粒蛋白含量低的京冬8号，下部层次则反之，后期中优9507与京冬8号下部层次的差异更为明显。硝酸还原酶活性(NRA)也自冠层顶部逐层降低，但其梯度变化趋势与含氮量变化趋势并不完全一致。中优9507NRA高于京冬8号，其垂直梯度值也高于京冬8号相应梯度。京冬8号上部叶片NRA与叶片含氮量具有较高的相关性，能较好地反映植株的氮素状况，而中优9507上、中部叶片NRA均可以反映其植株氮素状况。二者下层叶片NRA都表现出与叶片氮素消长的不同步性。

Vertical Distribution of Nitrogen and NRA in Canopy of Winter Wheat

The vertical distribution of leaf nitrogen (N) and nitrate reductase activity (NRA) in canopy of (Jingdong 8), a normal protein cultivar, and Zhongyou 9507, a higher protein cultivar, were investigated. (Apparent) (gradients) of N content and of leaf NRA in canopy were found in this study. N content in canopy (decreased) with the layer lowering. The N (gradient) of leaf in the upper layer of Zhongyou 9507 was higher than that of Jingdong 8 but it was reversed in the lower layer. There was an evident difference in N (gradient) of the lower layer between Zhongyou 9507 and Jingdong 8 in the last stage of growth. NRA in canopy also decreased with the layer lowering but it didn't show the completely same trends as N (gradient). Zhongyou 9507 had both higher NRA and vertical NRA (gradient) than that of Jingdong 8. There were a significant relationship between NRA and N content of leaf in the upper layer of Jingdong 8, but the NRA both in the upper and middle layers of Zhongyou 9507 could reflect N condition of leaf.