施氮对灌浆期冬小麦不同叶片SPAD值及光合速率的影响

Effect of Nitrogen on SPAD and Photosynthesis Rate of Different Leaves of Winter Wheat at Grain Filling Stage

为了解不同施氮水平下小麦叶片叶绿素含量和光合速率的变化,以冬小麦小偃22为供试材料进行小区试验,测定和分析了施氮后冬小麦灌浆期不同叶片的SPAD值及光合速率。结果表明,在同一施氮水平下,小麦植株不同叶片SPAD值及光合速率均为:旗叶>倒二叶>倒三叶>倒四叶,说明小麦叶片叶绿素含量及光合速率在植株上的分布特征相对固定,受施氮水平的影响较小。在施氮量小于90 kg/ha时,小麦各叶片SPAD值随施氮水平的增加而增大;当施氮量超过90 kg/ha时,小麦各叶片SPAD值变化趋势不明显。随施氮水平的提高,小麦叶片的光合速率呈现出先增加后下降的趋势,施氮量为135 kg/ha时光合速率最高。

This experiment was conducted to study the effect of nitrogen on SPAD and photosynthesis rate of different leaves of winter wheat at grain-filling stage with Xiaoyan 92, as test material. The resuits showed that there was significant difference of SPAD among different leaves under same nitrogen level. The order of leaves in both SPAD and photosynthesis rate were flag leaf 〉 the second leaf from top〉the third leaf from top〉the forth leaf from top. Therefore, the distribution of SPAD and photosynthesis rate among leaves of wheat plant was relatively stable, and was hardly affected by nitrogen level. The SPAD value increased with nitrogen level rising from 0 kg/ha to 90 kg/ha, but it changed little while above 90 kg/ha. With nitrogen level rising, photosynthesis rate of wheat leaf was raised in a range, then was reduced. The photosynthesis rate was the highest at the nitrogen level of 135 kg/ha.