Seasonal Responses of Hydraulic Function and Carbon Dynamics in Spruce Seedlings to Continuous Drought.
Seasonal Responses of Hydraulic Function and Carbon Dynamics in Spruce Seedlings to Continuous Drought.
复制标题
云杉幼苗水力功能和碳动力学对持续干旱的季节响应
DOI：
10.3389/fpls.2022.868108
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发表时间：
2022
影响因子：
5.6
通讯作者：
Yu, Dapao
中科院分区：
文献类型：
--
作者：
Han, Yangang;Deng, Jiaojiao;Zhou, Wangming;Wang, Qing-Wei;Yu, Dapao
关键词：
干旱的频率和持续时间预计将随着气候变化而增加。虽然水力功能和碳（C）储存已被广泛认为是植物在单一干旱下存活的关键组成部分，但对连续干旱的生理反应在很大程度上仍然未知，特别是对于对水分胁迫敏感的北方高温带和北方森林。在这项研究中，我们量化的生存，生长，气体交换，水的关系，和非结构性碳水化合物（NSC）在3岁的Jezo云杉（云杉）幼苗响应持续干旱胁迫。幼苗在干旱条件下保持了392天，包括两个生长和一个休眠的冬季。干旱胁迫下，幼苗在两个生长季的净光合速率（Anet）和气孔导度（gs）均显著下降，第二生长季的生物量显著下降。幼苗死亡率持续上升，至试验结束时达35.6%。值得注意的是，碳储量和叶水势对干旱的响应随季节变化很大。暴露于干旱和对照处理的活幼苗在两个生长季节中具有相似的NSC浓度。而根系可溶性糖和淀粉含量低于1%的幼苗则在冬季休眠期死亡。在第二生长季，干旱处理的幼苗叶水势和干材比导水率（Kw）显著低于对照。同时，叶片黎明前水势并没有在一夜之间恢复。这表明，C饥饿可能是导致冬休眠期幼苗死亡的重要原因，而生长期干旱则可能通过诱导水力衰竭而限制幼苗存活和生长。这种季节性依赖液压功能障碍和C耗竭可能会导致更高的死亡率在云杉林面临延长干旱持续时间预计在未来。
Drought is expected to increase in the frequency and duration associated with climate change. Although hydraulic function and carbon (C) storage have been widely recognized as key components to plant survival under a single drought, the physiological responses to continuous drought remain largely unknown, particularly for high northern temperate and boreal forests which are sensitive to water stress. In this study, we quantified the survival, growth, gas exchange, water relations, and nonstructural carbohydrates (NSCs) in 3-year-old Jezo spruce (Picea jezoensis) seedlings responding to continuous drought stress. Seedlings were maintained in drought conditions for 392 days, covering two growing and one dormant winter season. Seedlings subjected to drought showed a significant decrease in net photosynthesis rate (Anet) and stomatal conductance (gs) in both growing seasons, and biomass in the second growing season. The seedling mortality continuously increased to 35.6% at the experimental end. Notably, responses of C storage and leaf water potential to drought varied greatly depending on seasons. Living seedlings exposed to drought and control treatments had similar NSC concentrations in both growing seasons. However, seedlings with concentrations of both the soluble sugars and starch less than 1% in root died in the winter dormant season. In the second growing season, compared with the control treatment, droughted seedlings had significantly lower leaf water potential and stem wood-specific hydraulic conductivity (Kw). Meanwhile, the leaf predawn water potential did not recover overnight. These suggest that C starvation might be an important reason for seedlings that died in the winter dormant season, while in the growing season drought may limit seedling survival and growth through inducing hydraulic failure. Such seasonal dependence in hydraulic dysfunction and C depletion may lead to higher mortality in spruce forests facing extended drought duration expected in the future.
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