3种我国造林树种幼苗耐盐性评价及指标筛选

Comprehensive Evaluation and Index Screening of Salt Tolerance for Three Afforestation Specie Seedlings in China

[目的]研究苦楝、白榆和刺槐幼苗的耐盐性差异并筛选耐盐性评价指标。[方法]以1年生苦楝、白榆和刺槐幼苗为研究对象,设置0、100、200和300 mmol·L^(-1)NaCl处理,对各NaCl处理下3种幼苗的生物量、生理和生化指标进行分析。[结果](1) NaCl胁迫抑制了苦楝、白榆和刺槐幼苗的生物量,使其叶片相对含水量下降、电解质渗透率升高;(2)刺槐幼苗叶绿素含量随NaCl浓度升高而显著下降,但苦楝和白榆幼苗叶绿素a和叶绿素b含量仅在300 mmol·L^(-1)NaCl处理下显著降低;NaCl胁迫导致3种幼苗的光合作用参数Pn、Gs、Ci和E下降,而气孔限制值、水分利用效率、根和叶中游离脯氨酸和可溶性蛋白质含量、根和叶中CAT和APX活性升高;(3) NaCl胁迫改变了苦楝、白榆和刺槐幼苗体内的离子平衡状态,使3种幼苗根和叶中的Na+含量显著升高、叶中K^(+)含量升高;而根和叶中Mg^(2+)和Ca^(2+)以及根中K+含量的变化规律不完全一致。[结论]苦楝、白榆和刺槐幼苗耐盐能力强弱为白榆>苦楝>刺槐;根中游离脯氨酸和可溶性蛋白质含量、根和叶中CAT和APX活性、根中Ca^(2+)和叶中Na^(+)含量与苦楝、白榆和刺槐幼苗的耐盐性关联度较高,可作为耐盐性评价指标。

[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 Mg^(2+)and Ca^(2+)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,Ca^(2+)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.