两种高产小麦旗叶光合功能衰退特性的比较

以高产小麦宁麦8号和9号为材料,研究了自开花期旗叶光合功能衰退和品种间的差异。结果表明:开花期后,随着穗重的增加,旗叶的比叶重、相对含水量、叶绿素含量、饱和光强下的净光合速率P_nmax、光饱和点LSP、表观量子产量AQY以及PSI、PS II和全电子传递链活性不断降低,黄熟期后下降均较显著,而叶绿素a/b、光补偿点LCP和呼吸速率R_d开花期至黄熟期间缓慢升高。和宁麦8号相比,宁麦9号叶绿素含量开始时较低,衰老后期含量较高。结论:黄熟期前,旗叶对光的利用范围较光,光合功能降低缓慢;黄熟期后,利用强光和弱光能力均下降,光合功能的衰退显著。和宁麦8号相比,高产小麦宁麦9号旗叶光合功能早衰。

Comparison of photosynthetic decline of flag leaves between two high-yield wheat varieties

Photosynthetic properties were investigated in two newly-developed high-yield wheat (Triticum aesticum L.) varieties, Ningmai 8 and Ningmai 9, in order to elucidate both photosynthetic decline of flag leaf senescence, and variety differences. The results showed that, after anthesis, with increasing ear mass and specific leaf mass, there were decreases in relative water content, chlorophyll content, light-saturated net photosynthetic rate (P nmax ), light saturation point (LSP), apparent quantum yield (AQY), and electron transfer activities of PSI, PSII and whole electron transport chain, especially significant after yellow ripening, whereas ratio of chl a/b, light compensation point (LCP) and respiration rate (R d) were gradually increased from anthesis to yellow ripening, and after that rose markedly. The findings here indicated that before yellow ripening, P nmax decreased slowly with wider range of light availability, and after that P nmax dropped quickly with less range of light availability. Compared with Ningmai 8, Ningmai 9 with higher yield showed earlier senescence in flag leaves.