中文摘要：

以纽荷尔脐橙为材料,研究了不同光强（透光率分别为100%、34%和12%）对植物叶片PSⅡ功能和光能分配与利用的影响。结果表明,弱光显著降低了纽荷尔脐橙叶片的净光合速率、光饱和点和光补偿点,提高了表观量子效率、PSⅡ的最大光化学效率和光化学猝灭系数等。随着光强的减弱,PSⅡ天线色素吸收光能中分配于光化学反应的能量增加,分配于热耗散和荧光耗散的比例减少,但弱光与对照相比流经光化学反应的电子流量仍显著降低,说明弱光条件下纽荷尔脐橙叶片主要通过提高光能利用效率、转换效率和改变光能分配等进行适应性调节,对弱光逆境具有一定的生态适应性。

英文摘要：

The effects of different light intensity （100, 34 and 12% light intensity） on photosynthesis system Ⅱ （PS Ⅱ ） functions and absorbed light allocation in the Newhall navel orange leaves were investigated. The results showed that low light intensity significantly decreased net photosynthetic rate （Pn）, light saturating point （LSP） and light compensating point （LCP）, while apparent quantum yield （AQY）, maximal photochemical of PS Ⅱ （Fv/Fm） and photochemical quenching （qP） were increased. The decrease in light intensity was consistent with increasing the allocation of light absorbed by PSII antennae to the photochemical reaction, and decreasing the allocation of absorbed light to thermal dissipation and fluorescence dissipation. Compared with the control plants, the photochemistry electron flow of low light treatment plants was significantly decreased. To some extent, these results revealed that the Newhall navel orange plants had strong adaptability under low light conditions through improving utilizing light and transforming efficiency, and changing of absorbed light allocation. Overall, the Newhall navel orange plants had higher ecological adaptability.