Impact of groundwater depth on leaf hydraulic properties and drought vulnerability of Populus euphratica in the Northwest of China

Abstract

Key message Different groundwater conditions affect leaf hydraulic conductance and leaf pressure-volume parameters in Populus euphratica at the extremely arid zone in the northwest of China. Abstract Efficient water transport inside leaves constitutes a major determinant of plant function, especially in drought-stressed plants. The previous researches have reported the correlation between leaf hydraulic properties and water availability. In this study, we tested the hypothesis that water relation parameters of Populus euphratica in an extremely arid zone of China are sensitive and acclimated to groundwater depth. We measured leaf hydraulic conductance (K leaf ) using rehydration kinetics methods (RKM), pressure-volume (P-V) curves, and leaf vulnerability curves of P. euphratica growing at four groundwater depth gradients. We also assessed the hydraulic safety margins across groundwater depth gradients. We found that K leaf-max shows an increasing trend as the groundwater depth increases, while osmotic potential at full turgor (p ft ) and turgor loss point (W tlp ) exhibits a decreasing trend, suggesting that increased tolerance to drought is formed as the groundwater depth increases. Furthermore, safety margins showed positive and negative variations under different groundwater depths, indicating that P. euphratica has formed special drought survival strategies, which can be summarized as a ''conservative'' strategy in favorable water conditions or a ''risk'' strategy in severe drought stress.

Assessment of candidate distributions for SPI/SPEI and sensitivity of drought to climatic variables in China

“…Drought usually occurs in Northwest China (Pan et al, ; Liu et al, ) and North China (Liu et al, ; Xu et al, ). In recent years, serious droughts in humid Southern China occurred frequently (Xu et al, ; Wu et al, ; Lin et al, ; Wang et al, ).…”

Depressed hydraulic redistribution of roots more by stem refilling than by nocturnal transpiration for Populus euphratica Oliv. in situ measurement

“…Studies found that stem water storage was negatively associated with wood density in five coexisting temperate broad‐leaved tree species (Köcher, Horna, & Leuschner, ), suggesting the higher water storage as lower wood density. Many studies suggest that most Populus species are highly vulnerable to cavitation causing 50% loss of hydraulic conductivity ( P 50 ) occurring between −1 and −2.5 MPa (Hacke, ; Hukin, Cochard, Dreyer, Le Thiec, & Bogeat‐Triboulot, ; Pan, Chen, Chen, Wang, & Ren, ). For P. euphratica , the basic wood density of stem was less than that of the co‐occurring species, T. ramosissima , 0.41 versus 0.73 g/cm 3 (Yu et al., ), suggesting that P. euphratica can store more water than T. ramosissima .…”

Hydraulic Characteristics of Populus euphratica in an Arid Environment

“…P. euphratica can improve its water use efficiency accompanied by an increase in hydraulic capacity when it encounters severe water shortage. More specifically, the change in k ll in P. euphratica demonstrated an elastic LSC coincident with a conservative strategy in relatively moderate conditions, and a bolder strategy in relatively extreme conditions [16]. Plants can adapt to challenging conditions using their adaptive functional properties, resulting in the improvement of performance [48,49].…”

“…There is also no evidence for the coordination of water transport capacity among plant organs in P. euphratica. However, research on hydraulic conductance has been generally conducted on sections of specific plant parts (e.g., stems, leaves, shoots) in isolation from each other [16,17]. We know that water supply from roots to leaves depends on the integrity of flow in the xylem [18].…”