Waite Pierre-André, Leuschner Christoph, Delzon Sylvain, Triadiati Triadiati, Saad Asmadi, Schuldt Bernhard
Institute of Forest Botany and Forest Zoology, Technical University of Dresden, Pienner Straße 7, Tharandt 01737, Germany.
Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, Goettingen 37073, Germany.
Tree Physiol. 2023 Dec 12;43(12):2131-2149. doi: 10.1093/treephys/tpad113.
The predicted increase of drought intensity in South-East Asia has raised concern about the sustainability of rubber (Hevea brasiliensis Müll. Arg.) cultivation. In order to quantify the degree of phenotypic plasticity in this important tree crop species, we analysed a set of wood and leaf traits related to the hydraulic safety and efficiency in PB260 clones from eight small-holder plantations in Jambi province, Indonesia, representing a gradient in local microclimatic and edaphic conditions. Across plots, branch embolism resistance (P50) ranged from -2.14 to -2.58 MPa. The P50 and P88 values declined, and the hydraulic safety margin increased, with an increase in the mean annual vapour pressure deficit (VPD). Among leaf traits, only the changes in specific leaf area were related to the differences in evaporative demand. These variations of hydraulic trait values were not related to soil moisture levels. We did not find a trade-off between hydraulic safety and efficiency, but vessel density (VD) emerged as a major trait associated with both safety and efficiency. The VD, and not vessel diameter, was closely related to P50 and P88 as well as to specific hydraulic conductivity, the lumen-to-sapwood area ratio and the vessel grouping index. In conclusion, our results demonstrate some degree of phenotypic plasticity in wood traits related to hydraulic safety in this tropical tree species, but this is only in response to the local changes in evaporative demand and not soil moisture. Given that VPD may increasingly limit plant growth in a warmer world, our results provide evidence of hydraulic trait changes in response to a rising evaporative demand.
东南亚干旱强度预计增加，引发了对橡胶（巴西橡胶树）种植可持续性的担忧。为了量化这种重要林木作物品种的表型可塑性程度，我们分析了一组与水力安全和效率相关的木材和叶片性状，这些性状来自印度尼西亚占碑省八个小农户种植园的PB260克隆，代表了当地微气候和土壤条件的梯度变化。在各个地块中，枝条栓塞抗性（P50）范围为-2.14至-2.58兆帕。随着年平均水汽压差（VPD）增加，P50和P88值下降，水力安全边际增加。在叶片性状中，只有比叶面积的变化与蒸发需求差异有关。这些水力性状值的变化与土壤湿度水平无关。我们没有发现水力安全与效率之间的权衡，但导管密度（VD）成为与安全和效率相关的主要性状。与P50和P88以及比水力传导率、管腔与边材面积比和导管分组指数密切相关的是VD，而不是导管直径。总之，我们的结果表明，这种热带树种中与水力安全相关的木材性状存在一定程度的表型可塑性，但这仅响应于蒸发需求的局部变化，而非土壤湿度。鉴于在气候变暖的世界中VPD可能越来越限制植物生长，我们的结果提供了水力性状响应蒸发需求增加而变化的证据。
