中文摘要：

【目的】研究遮荫条件下非顺序衰老小麦旗叶和倒二叶叶绿素荧光特性的变化规律,揭示遮荫条件对小麦叶片非顺序衰老的影响。【方法】以非顺序衰老小麦温麦19、兰考矮早8、豫麦19和顺序衰老小麦陕229为材料,分别采用CCM-200手持式叶绿素仪和FMS-2型脉冲调制式荧光仪测定了遮荫和自然天气条件下小麦花后旗叶和倒二叶叶绿素含量及叶绿素荧光参数。【结果】无论在遮荫还是自然天气条件下,扬花至成熟期非顺序衰老小麦温麦19、兰考矮早8、豫麦19及顺序衰老小麦陕229旗叶和倒二叶叶绿素含量、PSⅡ实际光化学效率（ΦPSⅡ）、最大光化学效率（Fv/Fm）、PSⅡ潜在活性（Fv/F0）均呈下降趋势,而热耗散量子比率（F0/Fm）呈上升趋势,在花后30d非顺序衰老小麦和顺序衰老小麦的衰老现象差异显著。在自然天气条件下,花后30d非顺序衰老小麦温麦19、兰考矮早8和豫麦19旗叶的叶绿素含量、PSⅡ实际光化学效率（ΦPSⅡ）、最大光化学效率（Fv/Fm）、PSⅡ潜在活性（Fv/F0）分别比倒二叶低36.67%,29.91%和59.25%;34.87%,26.39%和22.15%;11.54%,13.54%和12.54%;23.05%,29.00%和17.14%,而热耗散量子比率（F0/Fm）旗叶分别比倒二叶高24.34%,25.54%和17.11%。在遮荫条件下,花后30d非顺序衰老小麦温麦19、兰考矮早8和豫麦19旗叶的叶绿素含量、PSⅡ实际光化学效率（ΦPSⅡ）、最大光化学效率（Fv/Fm）、PSⅡ潜在活性（Fv/F0）分别比倒二叶低20.04%,16.29%和21.66%;14.48%,17.26%和16.03%;8.64%,9.40%和10.63%;11.89%,19.91%和11.94%,而热耗散量子比率（F0/Fm）旗叶分别比倒二叶高16.08%,17.10%和17.48%。顺序衰老小麦陕229旗叶和倒二叶的表现正好与非顺序衰老小麦相反。【结论】遮荫条件明显延缓了叶片衰老,推迟了叶片非顺序和顺序衰老现象的发生,但不能改变叶片的衰老顺序。

英文摘要：

[Objective] Chlorophyll fluorescence characteristics of flag leaf and the second leaf were measured after flowering under shade and natural conditions were investigated to reveal the effect of shade condition on non-sequential senescence of wheat leaf. [Method] The chlorophyll content and chlorophyll fluorescence parameters of flag leaf and the second leaf in sequential senescence wheat Shaan 229 and non-sequential senescence wheat varieties Wenmai 19, Lankaoaizao 8 and Yumai 19 were measured in field using chlorophyll measuring system in hand and FMS-2 chlorophyll fluorescence meter after flowering under shade and natural conditions. [Result] Chlorophyll content, ФPS II ,Fv/Fm and Fv/F0 of flag leaf and the second leaf of tested wheat varieties from flowering to mature were in decreasing trend, while F0/Fm increased gradually under both shade and natural conditions. The difference between sequential senescence and non-sequential senescence varieties was significant 30 d after flowering. Under natural condition, chlorophyll content, ФPS II , Fv/Fm, and Fv/F0 of flag leaf for non-sequential senescence wheat varieties Wenmai 19,Lankaoaizao 8 and Yumai 19 30 d after flowering were 36. 67%,29.91% and 59.25%%;34.87%, 26.39% and 22.15%;11.54%,13.54% and 12.54%;23.05%,29.00% and 17.14% lower than those of the second leaf. F0/Fm of flag values of flag leaf of these varieties were 24.34%,25. 54% and 17. 11% higher than those of the second leaf. Under shade condition, chlorophyll content, ФPS II, Fv/Fm, and Fv/F0 of flag leaf for non-sequential senescence wheat varieties Wenmai 19, Lankaoaizao 8 and Yumai 19 were 20. 04%, 16. 29% and 21. 66%;14. 48%,17. 26% and 16. 03%;8. 64%,9. 40% and 10. 63%; 11.89%,19. 91% and 11. 94% lower than those of the second leaf. F0/Fm values of flag leaf were 16.08%,17.10% and 17.48% higher than those of the second leaf. The performance of flag leaf and the second leaf in sequential senescence wheat Shaan 229 and non-sequential senescence wheat is just the opposite. [Conclusion] Shade condi