Stronger cooling effects of transpiration and leaf physical traits of plants from a hot dry habitat than from a hot wet habitat
Stronger cooling effects of transpiration and leaf physical traits of plants from a hot dry habitat than from a hot wet habitat
复制标题
DOI：
10.1111/1365-2435.12923
复制
发表时间：
2017-12-01
影响因子：
5.2
通讯作者：
Fan, Zexin
中科院分区：
文献类型：
--
作者：
Lin, Hua;Chen, Yajun;Fan, Zexin
叶温对叶片的微环境和生理过程有重要影响。不同生境的植物有不同的叶温调节策略。在温室条件下，对38种冠层植物幼苗的22个叶片物理性状、蒸腾和热特性进行了研究，其中18种为湿热生境优势种，20种为干热生境优势种。为了区分蒸腾作用和叶片物理性状对叶温的影响，我们测量了有蒸腾作用和无蒸腾作用时叶温的日变化过程。同时测量每个个体旁边的参考叶的温度，以使温度具有可比性。一般来说，在相同条件下，来自HD的物种比来自HW的物种显示出更低的叶温度。HD植株的蒸腾能力和叶片物理性状的降温效应均较强。主动蒸腾作用为光合作用提供了适宜的热环境，而旱生叶在蒸腾作用受到抑制时可以缓解热胁迫。较高的叶脉密度和气孔面积指数（SPI）促进了HD植株较高的蒸腾能力。同时，HD植株的短叶片和薄下表皮在热传递方面更有效，但相关性远弱于所有物理性状的协同作用，证实了蒸腾作用和叶片物理性状为避免过热提供了双重保险，尤其是HD植株。我们强调，蒸腾作用是一个更有效的方式来冷却叶片比物理性状，当水分充足，这可能是一个重要的适应HD的降雨是零星的。研究结果进一步揭示了叶片物理性状与蒸腾作用对叶温调节的关系，以及叶片气体交换与热调节的协同进化。
Leaf temperature exerts an important impact on the microenvironment and physiological processes of leaves. Plants from different habitats have different strategies to regulate leaf temperature. The relative importance of physical traits and transpiration for leaf temperature regulation in the hot habitat is still unclear.We investigated 22 leaf physical traits, transpiration, and thermal properties of 38 canopy species of seedlings in a greenhouse, including 18 dominant species from a hot wet habitat (HW) and 20 dominant species from a hot dry habitat (HD). To separate the impact of transpiration and leaf physical traits on leaf temperature, we measured the diurnal courses of leaf temperatures with and without transpiration. The temperature of a reference leaf beside each individual was measured simultaneously to render temperatures comparable.Generally, the species from HD showed lower leaf temperatures than the species from HW under the same conditions. Both transpiration capacity and cooling effect of leaf physical traits were stronger for the plants from HD. Active transpiration provides a suitable thermal environment for photosynthesis, while xeromorphic leaves can dampen heat stress when transpiration is suppressed. Higher vein density and stomatal pore area index (SPI) facilitated higher transpiration capacity of the plants from HD. Meanwhile, shorter leaves and thinner lower epidermis of the plants from HD were more efficient in heat transfer, although relationships were much weaker than the synergic effect of all the physical traits.Our results confirmed that transpiration and leaf physical traits provided double insurance for avoiding overheating, particularly for plant from HD. We emphasize that transpiration is a more effective way to cool leaves than physical traits when water is sufficient, which may be an important adaptation for plant from HD where rainfall is sporadic. Our results provide further insight into the relationship between physical traits and transpiration for the regulation of leaf temperature, and the co-evolution of gas exchange and thermal regulation of leaves.A is available for this article.