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[目的]研究长期弱光对冬小麦(Triticum aestivumL.)群体光合速率(CAP)以及上3叶特别是旗叶光合特性的影响。[方法]以耐弱光性不同的冬小麦品种扬麦158和扬麦11为材料,设不遮光(S0)、从拔节至成熟期遮去小麦冠层自然光强的22%(S1)和33%(S2)3个处理,测定小麦CAP、上3叶的光合速率(Pn)、旗叶叶绿素含量以及籽粒产量。[结果]扬麦158和扬麦11CAP随遮光强度的增强而显著下降;长期弱光下,旗叶Pn显著下降,倒2叶Pn无明显变化,而倒3叶Pn则显著上升,从而部分地补偿了旗叶Pn的降低。该补偿效应因遮光强度和品种而异:S1处理的补偿效应大于S2处理,扬麦158的补偿效应大于扬麦11。在旗叶光合速率高值持续期内,长期遮光降低了扬麦158和扬麦11总叶绿素、叶绿素a和b的含量,以及叶绿素a/b值。[结论]弱光下,旗叶叶绿素a含量以及叶绿素a/b值下降引起其Pn显著降低,从而使得CAP明显降低,最终导致籽粒产量显著下降。该研究可为长江中下游地区的小麦生产提供重要的理论依据。
[Objective] The research aimed to study the effects of long-term low light on the photosynthetic rate (CAP) of winter wheat (Triticum aestivum L.) population and the photosynthetic characteristics of the upper third leaf, especially the flag leaf. [Method] The winter wheat cultivars Yangmai 158 and Yangmai 11 which were different in weaker light tolerance were set as non-light-shielded (S0), and the natural light intensity of wheat was shielded by 22% (S1) and 33 % (S2), the photosynthesis rate (Pn), flag leaf chlorophyll content and grain yield of wheat (CAP) were determined. [Result] Under Yangmai 158 and Yangmai 11CAP, the flag leaf Pn decreased significantly with long-term weak light intensity, Pn showed no significant change in the second leaf and Pn in the third leaf increased significantly, and thus partially Compensated for the decrease of flag leaf Pn. The compensation effect varies with shading intensity and variety: the compensation effect of S1 treatment is greater than S2 treatment, and the compensation effect of Yang Mai 158 is greater than that of Yang Mai 11. Long-term shading reduced the total chlorophyll, chlorophyll a and b contents and chlorophyll a / b values of Yangmai 158 and Yangmai 11 during the high duration of flag leaf photosynthesis. [Conclusion] Under weak light, the content of chlorophyll a and the decrease of chlorophyll a / b in flag leaf were significantly decreased, which led to the decrease of CAP and the decrease of grain yield. This study can provide important theoretical basis for wheat production in the middle and lower reaches of the Yangtze River.