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作 者 ：张健,张金政,姜闯道,李志强,石雷,李振宇

期 刊 ：生态学报 2008年 28卷 8期 页码：3637~3643

关键词：鸢尾；叶片取向；光合作用；光抑制；叶绿素荧光；叶黄素循环；

Keywords:Iris L., leaf orientation, photosynthesis, photoinhibition, chlorophyll fluorescence, xanthophyll cycle,

摘 要 ：通过气体交换、叶绿素荧光、反射光谱等方法，研究了鸢尾叶片取向对植株光合特性及光抑制的影响。自然状态下，鸢尾的叶片不同取向影响植株对光能的截获；叶片净光合速率Pn与光合有效辐射PAR呈极显著相关；东西取向叶片的Pn要大于南北取向。南北取向的植株中叶片叶绿素(Chl a和Chl b)，类胡萝卜素(Car)含量略高于东西取向。日进程中，各取向的叶片在一天中均没有发生明显的光抑制。相对于东西取向的植株，南北取向植株发生了明显的倾斜；在两种取向的植株中，叶片东侧和南侧的光化学反射指数（PRI）下调幅度较大；PRI的变化量（△PRI）大小依次为：东侧>南侧>西侧>北侧。鸢尾植株取向改变了叶片倾斜角度，两者共同导致光能截获减小；同时，叶片光能利用效率下调和叶黄素循环增强，这可能是不同取向植株均未发生严重光抑制的原因。

Abstract:Gas exchange, chlorophyll a fluorescence kinetics and reflectance spectroscopy were investigated to explore photosynthetic characteristics and photoinhibition in Iris L. seedling leaves. Leaf orientation had a great influence on the irradiance interception of leaves under natural conditions. Net photosynthetic rate (Pn) in Iris L. seedling leaves was linearly correlated with photosynthetic active radiation (PAR). Leaves grown with east-west orientation had a higher Pn than that in leaves grown with south-north orientation. Compared with the east-west grown leaves, the leaves grown with south-north orientation contained relatively higher chlorophyll content (Chl) and carotenoid content (Car). During daily courses, no serious photoinhibition was induced in leaves with all orientations. Interestingly，the south-north grown leaves showed a more noticeable incline than the east-west grown leaves. In addition, photochemical reflectance index (PRI) in leaves grown with east and south orientation were significantly down regulated; changes of PRI (△PRI) ranked in the order of east > south > west > north. Thus, we deduced that the co-operation of leaf orientation and the incline of leaves reduce the irradiance interception of leaves in field; the down-regulation of the efficiency of light energy utilization and the strengthening of xanthophyll cycle might alleviate the photoinhibion in Iris L. leaves.

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