Wu Sipan, Gu Xiaoxuan, Zheng Yanghang, Chen Luzhen
State Key Laboratory of Marine Environmental Science, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China.
Front Plant Sci. 2023 May 8;14:1118970. doi: 10.3389/fpls.2023.1118970. eCollection 2023.
As part of the plant water-use process, plant nocturnal sap flow ( ) has been demonstrated to have important ecophysiological significance to compensate for water loss. The purpose of this study was to explore nocturnal water-use strategies to fill the knowledge gap in mangroves, by measuring three species co-occurring in a subtropical estuary. Sap flow was monitored over an entire year using thermal diffusive probes. Stem diameter and leaf-level gas exchange were measured in summer. The data were used to explore the different nocturnal water balance maintaining mechanisms among species. The existed persistently and contributed markedly over 5.5%~24.0% of the daily sap flow () across species, which was associated with two processes, nocturnal transpiration ( ) and nocturnal stem water refilling ( ). We found that the stem recharge of the and occurred mainly after sunset and that the high salinity environment drove higher while stem recharge of the mainly occurred in the daytime and the high salinity environment inhibited the . The diversity of stem recharge patterns and response to sap flow to high salinity conditions were the main reasons for the differences in / among species. For and , was the main contributor to , which was driven by the demands of stem water refilling after diurnal water depletion and high salt environment. Both of the species have a strict control over the stomata to reduce water loss at night. In contrast, maintained a low , driven by vapor pressure deficit, and the mainly used for , which adapts to high salinity conditions by limiting water dissipation at night. We conclude that the diverse ways properties act as water-compensating strategies among the co-occurring mangrove species might help the trees to overcoming water scarcity.
作为植物水分利用过程的一部分，植物夜间液流（ ）已被证明对补偿水分损失具有重要的生态生理意义。本研究的目的是通过测量亚热带河口共生的三种植物，探索夜间水分利用策略，以填补红树林相关知识空白。使用热扩散探针全年监测液流。在夏季测量茎直径和叶片水平的气体交换。这些数据用于探索不同物种间夜间水平衡维持机制的差异。夜间液流持续存在，占各物种日液流（ ）的5.5%~24.0%，这与两个过程有关，即夜间蒸腾（ ）和夜间茎干水分再补充（ ）。我们发现，白骨壤和桐花树的茎干再补充主要发生在日落后，高盐环境促使更高的夜间蒸腾，而秋茄的茎干再补充主要发生在白天，高盐环境抑制了其夜间蒸腾。茎干再补充模式的多样性以及液流对高盐条件的响应是物种间夜间蒸腾/茎干再补充差异的主要原因。对于白骨壤和桐花树，茎干再补充是夜间蒸腾的主要贡献因素，这是由日间水分消耗后茎干水分再补充的需求和高盐环境驱动的。这两个物种都严格控制气孔以减少夜间水分损失。相比之下，秋茄保持较低的夜间蒸腾，由水汽压差驱动，其茎干再补充主要用于维持膨压，通过限制夜间水分散失来适应高盐环境。我们得出结论，共生红树林物种间夜间液流特性作为水分补偿策略的多样方式可能有助于树木克服水分短缺。
