Effects of Complex Salt and Alkali Conditions on Seed Germination and Seedling Chlorophyll Fluorescence Characteristics of Alfalfa

Seeds and young seedlings of alfalfa(Medicago sativa) were stressed with 20 different alkali-saline conditions simulating salt-alkalinized soil obtained by mixing two neutral salts(NaCl and Na2SO4) and two alkaline salts(NaHCO3 and Na2CO3) in various proportions.Under these conditions,the germination rate,germination viability,germination process,photochemical efficiency of PSⅡ(Fv/Fm),potential activity of PSⅡ(Fv/Fo) and chlorophyll content were determined.Results showed that except group A,salt had a negative effect on the germination rate and germination viability of seeds.In the same salt concentrations,the germination process was postponed with increased proportions of alkali salt.As the stress increased,the chlorophyll content increased initially then decreased,Fv/Fm,Fv/Fo were significantly decreased.