title: [Effects of site conditions and tree age on Robinia pseudoacacia and Populus simonii leaf hydraulic traits and drought resistance].
abstract: In order to elucidate the hydro-physiological mechanisms of the formation of 'dwarf and aged' trees, two typical tree species Robinia pseudoacacia and Populus simonii on the Loess Plateau were chosen as the test objects to study their leaf hydraulic traits and drought resistance under effects of site conditions (gully bottom tableland and inter-gully slopeland) and tree age. For both R. pseudoacacia and P. simonii, the trees growing on the wet tableland had higher leaf maximum hydraulic conductance (Kmax) and hydraulic vulnerability (P50), and the Kmax decreased with tree age but the P50 had less difference, as compared with the trees growing on the dry slopeland. The trees growing on the tableland also had higher leaf epidermal conductance and PV curve parameters (including relative water content at turgor pressure loss point RWC(tlp), water potential at turgor pressure loss point psi(tlp), and osmotic potential at saturated water content psi(sat), and the leaf epidermal conductance decreased significantly with tree age whereas the PV curve parameters had definite decrease. The Kmax was significantly positively correlated with psi(tlp), and the P50 had definite correlations with PV curve parameters, suggesting that there existed a tradeoff relationship between Kmax and drought resistance, and P50 was an important drought-resistant trait for the two tree species.
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, Shaanxi, China. lijh1987@163.com
authors.forename: Jun-Hui
authors.initials: JH
authors.lastname: Li
authors.forename: Yang-Yang
authors.initials: YY
authors.lastname: Li
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Zhao
authors.forename: Li-Xiang
authors.initials: LX
authors.lastname: Zuo
mesh_terms: D000222:Adaptation, Physiological; D000531:Altitude; D002681:China; D055864:Droughts; D017753:Ecosystem; D018515:Plant Leaves / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology; D032107:Populus / Q000502:physiology*; D031301:Robinia / Q000502:physiology*; D013997:Time Factors; D014867:Water / Q000502:physiology*
chemical_list: D014867:Water