Physiological Characteristics Of Nodulation Induced By CTS In Vegetable Soybean Under NaCl Stress

Saline-alkali stress is one of the main adverse factors in agricultural production.In the process of planting crops,in addition to paying attention to environmental factors and soil improvement,a convenient,cheap and pollution-free method is also needed to alleviate the damage caused by salt stress on plants.Previous studies have shown that chitosan(CTS)can significantly improve the resilience of plants.This study salt-tolerant varieties’ green-collar ’8 inoculation with good slow rhizobia symbiosis matching USDA122,salt sensitive varieties’ Japan’s green inoculation with good fast coexisting phase matching of rhizobia HH103 two symbionts as experimental materials,study of chitosan under salt stress of food with soybean root hair growth and nitrogen fixation of nodule induction effect,To explore the effects of chitosan on the metabolism,root accumulation and the dynamic changes of nodulation related substances such as isoflavones and auxin in vegetable soybean under salt stress,so as to explore the physiological regulation function of chitosan in promoting nodulation in vegetable soybean.The main results are as follows:1.Chitosan under salt stress,effect on food with soybean nitrogen fixation of nodule and exogenous chitosan under salt stress food with soybean nodule number,nodule fresh weight,plant nitrogen content,plant dry weight were significantly improved,the salt stress when 30 days varieties ’lvlingbahao’ and ’JNippon Green’ The nodule number,plant nitrogen content and plant dry weight increased by 24%,19%;14%,11% and 32%,59%,respectively,indicating that chitosan can significantly improve the nodule formation and nitrogen fixation ability of vegetable soybean under salt stress and promote plant growth.2.Chitosan under salt stress of food with soybean root hair growth,the influence of exogenous alleviate chitosan by membrane lipid peroxidation,reduced the salt stress damage to food with soybean roots,promote hair growth,’lvlingbahao’ and ’JNippon Green’in salt stress when 2 days deformation of the total amount of root hair and hair growth in the number of 49%,94% and 12%,36%,respectively,The results showed that root hair was an important channel of infection of rhizobia,and the improvement of its growth and development could effectively promote infection of rhizobia,and then promote nodulation.3.Salt stress significantly inhibited the synthesis and metabolism of vegetable soybean isoflavones,while exogenous chitosan significantly increased the activities of the key enzyme for isoflavone synthesis(Chalcone isomerase)and the important enzyme for isoflavone accumulation(glutathione transferase),and promoted the synthesis and accumulation of isoflavones in roots.Under 5 days of stress,daidzein and genistein increased by 66%,193% and 45%,174% in roots of ’lvlingbahao’ and ’JNippon Green’,respectively.Isoflavones are the key substances for signal transmission and recognition during nodule formation,and the increase of isoflavone content can effectively promote the infection of rhizobia,and then promote nodule formation.4.Salt stress significantly inhibited the aboveground and underground auxin metabolism of vegetable soybean.Exogenous chitosan significantly increased the activities of auxin synthesis-related enzymes such as tryptophan synthase and tryptophan aminotransferase in vegetable soybean under salt stress,promoted the formation of tryptophan,and then significantly improved the auxin synthesis efficiency.In addition,chitosan significantly inhibited the activity of indole acetic acid oxidase,reduced the oxidative decomposition of auxin,and effectively promoted the accumulation of auxin in roots.Auxin is the key substance to induce the infection of rhizobia and promote the formation of nodule primordia.The increase of auxin content can effectively promote the formation and growth of nodule,and then increase the number of nodule formation.