Effects of exogenous 5-aminolevulinic acid on seed germination and physiological characteristics of Cassia obtusifolia seedlings under NaCl stress

Objective In order to improve the salt resistance activity of seeds and seedlings for Cassia obtusifolia under NaCl stress,seed germination and physiological characteristics of C.obtusifolia seedlings were investigated.Methods Several physiological indexes of C.obtusifolia seeds treated by exogenous 5-aminolevulinic acid(ALA) under NaCl stress,such as germination vigor,germination rate,germination index,and vigor index,were measured.And other indexes,contents of photosynthetic pigment,chlorophyll fluorescence parameters,membrance permeability,contents of malondialdehyde(MDA),soluble sugar,soluble protein and proline,activities of superoxide(SOD),peroxidase(POD),and catalase(CAT) were also measured.Results The germination indexes of C.obtusifolia seeds under NaCl stress(100 mmol/L) have an obvious inhibition.But after the treatment of ALA,all germination indexes were increased.The results showed that the treatment of exogenous ALA obviously improved the germination vigor,germination rate,germination index,and vigor index,increased the content of chlorophyll a,chlorophyll b,and total chlorophyll,improved the photochemical efficiency of photosystem II(Fv/Fm),photochemical efficiency(Fv′/Fm′),PSII actual photochemical efficiency(ΦPSII),and photochemical quench coefficient(qP),decreased the membrance permeability,the contents of MDA and non-photochemical quenching coefficient(NPQ),increased the content of soluble sugar,soluble protein and proline.Meanwhile,the