Guangdong Provincial Key Laboratory of Applied Botany, State Key Laboratory of Plant Diversity and Specialty Crops, Key Laboratory of National Forestry and Grassland Administration on Plant Conservation and Utilization in Southern China, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Photosynth Res. 2024 Oct;162(1):1-12. doi: 10.1007/s11120-024-01110-9. Epub 2024 Jul 31.
Changes in rainfall patterns are important environmental factors affecting plant growth, especially when larger precipitation events and prolonged drought periods occur in subtropical regions. There are many studies on how drought reduces plant biomass through drought-sensitive functional traits, but how excess water affects plant growth and ecophysiology is still poorly understood. Therefore, a greenhouse experiment was conducted on Schima superba (Theaceae), a dominant tree species in subtropical forests and commonly used in forestry, in a closed chamber under control (25% soil water content (SWC) as in local forests), drought stress (D, 15% SWC) and moisture stress (W, 35% SWC). Plant growth and ecophysiological traits related to morphology, leaf gas exchange, water potential and structural traits were measured. Compared to control, S. suberba under dry conditions significantly decreased its aboveground biomass, photosynthetic rate (A), leaf water potential and nitrogen use efficiency, but increased intrinsic water use efficiency, root to shoot ratio and specific root length. S. superba under wet conditions also significantly decreased its total biomass, aboveground biomass and specific root length, while W had no effect on A and leaf water potential. Our results indicate that S. superba shows a decrease in carbon gain under drought stress, but less response under wet conditions. This emphasizes the need to consider the strength and frequency of rainfall pattern changes in future studies because rainfall may either alleviate or intensify the effects of drought stress depending on the moisture level, thus suitable water conditions is important for better management of this tree species in subtropical China.
降雨模式的变化是影响植物生长的重要环境因素，特别是在亚热带地区发生较大降水事件和长时间干旱期时。有许多研究探讨了干旱如何通过对干旱敏感的功能特征来降低植物生物量，但过量的水如何影响植物生长和生态生理学仍知之甚少。因此，我们在温室中以亚热带森林中的优势树种（樟科）红荷木为对象，开展了一个密闭箱实验，分别设置对照（25%土壤含水量（SWC），与当地森林中的含水量相同）、干旱胁迫（D，15% SWC）和水分胁迫（W，35% SWC）。我们测量了与形态、叶片气体交换、水势和结构特征相关的植物生长和生态生理特征。与对照相比，干旱条件下的红荷木显著降低了地上生物量、光合速率（A）、叶片水势和氮利用效率，但增加了内在水分利用效率、根冠比和比根长。水分条件下的红荷木也显著降低了总生物量、地上生物量和比根长，而 W 对 A 和叶片水势没有影响。我们的结果表明，红荷木在干旱胁迫下碳获取减少，但在水分条件下响应较小。这强调了在未来研究中需要考虑降雨模式变化的强度和频率，因为降雨可能会根据水分水平缓解或加剧干旱胁迫的影响，因此，在亚热带中国，适宜的水分条件对这种树种的更好管理很重要。
