Contributions of species shade tolerance and individual light environment to photosynthetic induction in tropical tree seedlings
Contributions of species shade tolerance and individual light environment to photosynthetic induction in tropical tree seedlings
复制标题
物种耐荫性和个体光环境对热带树苗光合诱导的贡献
DOI：
10.1093/treephys/tpac056
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发表时间：
2022
期刊：
影响因子：
4
通讯作者：
Tang Yanhong
中科院分区：
文献类型：
--
作者：
Kang Huixing;Tomimatsu Hajime;Zhu Ting;Ma Yixin;Wang Xiruo;Zhang Yan;Tang Yanhong
长期以来，来自阴暗环境的树叶是否比来自阳光充足的环境的树叶表现出更高的光合诱导效率（IE）以及树种的耐荫性和树叶的光环境如何影响光合作用的动态一直是争论的焦点。为了解决这些问题，我们研究了具有不同耐荫性的六种树种的幼苗对模拟光强度变化的叶片光合反应。这些幼苗在低地热带森林的不同光照环境下生长。我们提出了相对耐荫性（RST）指数来评估物种特定的耐荫能力，并通过日光积分（DLI）指数（平均每日总光强度）来量化单个叶子的光环境。我们得到了以下结果。光合 IE（即已实现的碳增益与预期碳增益的比率）对于 RST 较高的物种明显高于 RST 较低的物种。光环境对同一物种内单叶IE的影响在不同物种之间存在很大差异。在 RST 相对较低的三个物种中，当 DLI < 10 mol m−2d−1 时，单个叶子的 IE 在较高 DLI 下下降。诱导前初始气孔导度 (gs50) 高的幼苗比同一物种的低 gs50 的幼苗具有更高的 IE。 IE 和稳态光合速率之间存在权衡。这些结果表明物种的耐荫性与单叶光合作用诱导的光环境之间存在复杂的相互作用，并为林下幼苗在日光环境下的适应策略提供了新的见解。
It has long been debated whether tree leaves from shady environments exhibit higher photosynthetic induction efficiency (IE) than those from sunny environments and how the shade tolerance of tree species and the light environment of leaves contribute to the dynamics of photosynthesis. To address these questions, we investigated leaf photosynthetic responses to simulated changes of light intensity in seedlings of six tree species with differential shade tolerance. The seedlings were growing under different light environments in a lowland tropical forest. We proposed an index of relative shade tolerance (RST) to assess species-specific capacity to tolerate shade, and we quantified the light environment of individual leaves by the index of daily light integral (DLI), the averaged daily total light intensity. We obtained the following results. Photosynthetic IE, which is the ratio of the achieved carbon gain to the expected carbon gain, was significantly higher for species with a higher RST than for that with a lower RST. The impacts of light environment on the IE of individual leaves within the same species varied largely among different species. In the three species with relatively low RST, the IE of individual leaves decreased at higher DLIs when DLI < 10 mol m−2d−1. Seedlings with high initial stomatal conductance before induction (gs50) possessed a higher IE than those with lowgs50from the same species. A trade-off existed between IE and steady-state photosynthetic rates. These results suggest a complex interaction between the shade tolerance of species and the light environments of individual leaves for photosynthetic induction and provide new insights into the adaptation strategy for understory seedlings under sunfleck environments.