《植物生理学报》 2018, 54(1): 54-62

夏季小花睡莲挺水叶光抑制加剧的机制

张雅君^1,2, 吴含玉¹, 张会金¹, 姜闯道^1,*

¹中国科学院植物研究所, 中国科学院北方资源植物重点实验室, 北京100093; ²中国科学院大学, 北京100049

通信作者：姜闯道；E-mail: jcdao@ibcas.ac.cn

摘　要：

为理解夏季睡莲叶片挺水前后光合特性的变化, 以雪白睡莲和小花睡莲为材料比较了浮水和挺水条件下两者叶温、相对含水量、气体交换和叶绿素荧光的差异以及与气孔形态的关系。结果表明, 小花睡莲和雪白睡莲气孔器大小相似, 但前者气孔密度明显高于后者, 故小花睡莲浮水叶片的气孔导度和蒸腾速率较雪白睡莲高。小花睡莲挺水叶片的光合速率、气孔导度和蒸腾速率均明显低于浮水叶片, 不过这种差异在雪白睡莲中不明显。相对于雪白睡莲, 小花睡莲挺水叶片午间除叶温明显升高外, 叶片相对含水量下降幅度更大; 遮阴可以一定程度上改善小花睡莲挺水叶的水分状况。进一步研究显示, 小花睡莲挺水叶中午发生了严重光抑制, 而雪白睡莲挺水叶的光抑制则较轻。因此, 推测小花睡莲叶片水分平衡能力较弱, 挺水叶水分失衡容易导致叶温升高和光合速率下降, 最终加剧光抑制并致使叶片死亡。本研究对阐述北方夏季栽培条件下一些睡莲品种挺水叶易发生死亡的原因具有一定意义。

关键词：睡莲; 光合作用; 气孔; 气体交换; 叶绿素荧光; 叶温

收稿：2017-10-09   修定：2017-12-11

资助：国家自然科学基金(31571576)。

Mechanism of photoinhibition in emerged leaf of Nymphaea micrantha Guill. & Perr. in summer

ZHANG Ya-Jun^1,2, WU Han-Yu¹, ZHANG Hui-Jin¹, JIANG Chuang-Dao^1,*

¹Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; ²University of Chinese Academy of Sciences, Beijing 100049, China

Corresponding author: JIANG Chuang-Dao; E-mail: jcdao@ibcas.ac.cn

Abstract:

The differences of stomatal morphology, leaf temperature, relative water content, gas exchange and chlorophyll a fluorescence were compared with two water lily varieties (Nymphaea candida C. Presl and Nymphaea micrantha Guill. & Perr.) in order to understand changes of photosynthetic characteristics between floating leaf and emerged leaf. The results showed that the stomatal size of Nymphaea micrantha and Nymphaea candida were similar, but the former had a much higher density than the latter. Therefore, the stomatal conductance and transpiration rate of Nymphaea micrantha were higher than Nymphaea candida. In Nymphaea micrantha, the floating leaves had higher net photosynthetic rate, stomatal conductance and transpiration rate than emerged leaves. But the differences were not obvious in Nymphaea candida. Besides the higher leaf temperature, the former also had more decrease in relative water content than the latter; shading can alleviate water deficiency to some extent. Further study revealed that serious photoinhibition happened in the emerged leaves of Nymphaea micrantha, but not Nymphaea candida. Accordingly, we thought that the emerged leaf of Nymphaea micrantha needed more water to maintain hydrologic balance due to high stomatal density and transpiration rate. The imbalance of water induced the increase of leaf temperature and decline of net photosynthetic rate, which eventually aggravated photoinhibition and resulted in leaf death. This study is of significance for revealing the death of emerged leaves of some water lily varieties in summer under the northern cultivation condition.

Key words: water lily; photosynthesis; stomata; gas exchange; chlorophyll fluorescence; leaf temperature