Abstract: To assess the responses of leaf chlorophyll fluorescence kinetics parameters to soil water stress, the diurnal variation of leaf chlorophyll fluorescence kinetics parameters of six sandfixation tree species (Salix psammophila C. Wang et Ch.Y. Yang, Salix gordejevii Y.L. Chang et Skv., Elaeagnus angustifolia L., Ampelopsis aconitifolia var. glabra Diels, Amorpha fruticosa L., and Ammopiptanthus mongolicus (Maxim. ex Kom.) S.H. Cheng) were determined with a portable modulated chlorophyll fluorescence spectrometer (Mini-PAM) in the growing season in 2015. The results showed that the diurnal variations of quantum yield (Yield), the apparent photosynthetic electron transport rate (ETR), the maximum photochemical efficiency of PSⅡ (F_v/F_m) and nonphotochemical quenching (NPQ) were obviously of singlepeak curve. Yield, ETR and F_v/F_m decreased with the decrease of soil water, while NPQ increased. These results indicated that the chlorophyll fluorescence kinetics parameters could be used as evaluation indicators of resistance. The response of F_v/F_m was most sensitive to the change of soil moisture. The sensitivity of F_v/F_m to soil moisture for the six tree species ranked in the order of Ammopiptanthus mongolicus > Salix psammophila > Salix gordejevii > Ampelopsis aconitifolia > Amorpha fruticose > Elaeagnus angustifolia. In conclusion, xerophilous tree species was most sensitive to soil moisture change, followed by mesophilous and hygrophilous tree species.

Key words: tomato, defense priming, Funneliformis mosseae, mechanical wounding