Root morphological and physiological responses of Alhagi sparsifolia to drought stress in the lower reaches of the Tarim River, China

摘要

We selected four representative sites along the lower reaches of the Tarim River to evaluate the adaptability of Alhagi sparsifolia to drought. The Soil Water Content (SWC) and groundwater table as well as fine Root Length (RL), Root Surface area (RS), Root Weight Density (RWD), leaf water potential (ψ_(leaf)), Leaf Area (LA), Electron Transport Rate (ETR), quantum yield of photosystemII (Y), and Water Use Efficiency (WUE) of Alhagi sparsifolia were investigated and analyzed during August and September. Our results suggested that the decrease of SWC and groundwater table along the river way resulted in significant variations in RL, RS, RWD, ψ_(leaf) and LA, respectively, (P < 0.05), while weak changes in other physiological parameters including ETR, Y and WUE. In combination with the significant linear regressions between RSD and SWC as well as the significant correlation between RS and ψ_(leaf) (P < 0.05), it was indicated that root morphology was more sensitive to drought stress than physiology of this plant and the adjustment of root morphology was one of the critical strategies for Alhagi sparsifolia to cope with typically low soil water or deep groundwater condition in arid inland river basin.