Effects of soil water stress on seedling growth and water use efficiency of two desert shrubs

Seedling growth,water use efficiency and leaf carbon isotope composition(δ13C value) of Zygophyllum xanthoxylum and Caragana korshinskii were measured at different soil water stress levels in a pot experiment.The correlation between growth and water use efficiency was analyzed.1) Severe water stress seriously decreased the total biomass,above ground biomass,total leaf area and leaf number of Z.xanthoxylum and C.korshinskii;2) As water stress increased,water use efficiency and the δ13C value increased.Water use efficiency and the δ13C value had a significant(P0.05) positive relationship;3) Water use efficiency had a significant negative relationship with total leaf area,leaf number(P0.01),and total biomass(P0.05);4) The biomass and total leaf area of C.korshinskii were significantly smaller than those of Z.xanthoxylum,but the root/shoot ratio was bigger.C.korshinskii is sensitive to water stress and its biomass,leaf area and leaf number are considerably reduced by this stress;5) Under the same water stress gradient,water use efficiency of C.korshinskii is lower but the δ13C value is higher than those of Z.xanthoxylum.