Li Jun-Hui, Li Yang-Yang, Zhao Li-Min, Zuo Li-Xiang
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.
Ying Yong Sheng Tai Xue Bao. 2012 Sep;23(9):2397-403.
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.
为阐明“矮化老龄”树形成的水分生理机制，选取黄土高原两种典型树种刺槐和小叶杨作为试验对象，研究其在立地条件（沟底台地和沟间坡地）和树龄影响下的叶片水力特征及抗旱性。对于刺槐和小叶杨，生长在湿润台地的树具有较高的叶片最大水力导度（Kmax）和水力脆弱性（P50），与生长在干燥坡地的树相比，Kmax随树龄降低，而P50差异较小。生长在台地的树也具有较高的叶片表皮导度和PV曲线参数（包括膨压丧失点相对含水量RWC(tlp)、膨压丧失点水势psi(tlp)和饱和含水量渗透势psi(sat)），且叶片表皮导度随树龄显著降低，而PV曲线参数有一定程度降低。Kmax与psi(tlp)显著正相关，P50与PV曲线参数有一定相关性，表明Kmax与抗旱性之间存在权衡关系，P50是这两种树种重要的抗旱性状。
