Comprehensive Evaluation and Index Screening of Salt Tolerance for Three Afforestation Specie Seedlings in China
[Objective]To study the differences in salt tolerance among the Melia azedarach,Ulmus pumila and Robinia pseudoacacia seedlings and to select the evaluation indexes of salt tolerance.[Method]Based on the one-year-old seedlings of M.azedarach,U.pumila and R.pseudoacacia,the effects of differ-ent NaCl concentrations(0,100,200 and 300 mmol·L-1)on the seedling biomass,physiological and bio-chemical indexes were analyzed.[Result](1)NaCl stress inhibited the biomass of M.azedarach,U.pum-ila and R.pseudoacacia seedlings,decreased the relative water content of leaves and increased the elec-trolyte permeability.(2)The contents of chlorophyll a and b in R.pseudoacacia decreased significantly with the increase in NaCl concentration.But the chlorophyll content in M.azedarach and U.pumila seedlings only decreased significantly under 300 mmol·L-1 NaCl treatment.The photosynthetic parameters Pn,Gs,Ci and E decreased under NaCl stress in the 3 tree seedlings,but the stomatal limitation and water use ef-ficiency increased.Meanwhile,the concentrations of free proline and soluble protein,as well as the activit-ies of CAT and APX in roots and leaves also increased.(3)NaCl stress changed the ion balance in the roots and leaves of the 3 tree seedlings.The Na+concentration in roots and leaves and K+concentra-tion in leaves of the 3 tree seedlings significantly increased under NaCl stress,but the concentration of K+in roots,as well as the concentrations of Mg2+and Ca2+in roots and leaves had differential changes.[Conclusion]The seedlings of U.pumila have the strongest salt tolerance,followed by M.azedarach,R.pseudoacacia.The concentrations of free proline and soluble protein in roots,CAT and APX activities in roots and leaves,Ca2+in roots and Na+in leaves are highly correlated with salt tolerance of the 3 tree seedlings,which can be used as the evaluation indexes of salt tolerance.
salinizationsalt toleranceadaptability evaluationsalt tolerance index
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