Effects of Extracellular Polysaccharides on Seed Germination,Seedling Growth and Physiological Characteristics of Schizonepeta tenuifolia under Salt Stress

TANG Qian; WANG Jiali; LI Wenqiang

doi:10.15933/j.cnki.1004-3268.2024.10.011

Abstract：In order to improve the planting efficiency of Schizonepeta tenuifolia in saline soil,the effects of extracellular polysaccharides from Lactobacillus plantarum on seed germination and seedling growth under salt stress were explored,and the specific mechanism was analyzed from the physiological characteristics of seedling roots.Six treatments were set up:blank control group(CK1),salt stress control group(CK2),50 mg/kg extracellular polysaccharide group(T1),100 mg/kg extracellular polysaccharide group(T2),200 mg/kg extracellular polysaccharide group(T3),and 400 mg/kg extracellular polysaccharide group(T4).The results showed that extracellular polysaccharides significantly promoted the seed germination and seedling growth of Schizonepeta tenuifolia.Among them,the effect of adding 200 mg/kg extracellular polysaccharide(T3)was the most significant.Compared with CK2,the seed germination rate,germination potential,germination index and vigor index were significantly increased by 76.13%,144.16%,137.45%and 265.28%,respectively.The plant height,stem diameter,underground dry weight and aboveground dry weight of seedlings were significantly increased by 60.49%,14.73%,40.08%and 85.39%,respectively.The contents of proline,soluble protein and soluble sugar were increased by 21.02%,84.56%and 40.02%,respectively.The content of Na+was decreased by 54.63%,the K+content was increased by 95.24%,and the Na+/K+value decreased by 76.76%.The root electrolyte leakage rate and malondialdehyde(MDA)content decreased by 44.54%and 43.24%,respectively,and the activities of superoxide dismutase(SOD),catalase(CAT),and peroxidase(POD)increased by 30.39%,34.59%and 24.31%,respectively.In summary,the extracellular polysaccharides of Lactobacillus plantarum can improve the salt resistance of seedlings through root osmotic regulation and activation of antioxidant enzyme defense system,thereby promoting seed germination and seedling growth of Schizonepeta tenuifolia.