Salt Tolerance Strains Screen And Salt Resistance Mechanism Study Of Helianthus Tuberosus L.

Soil salinization is a global problem that affects agricultural production and environments.In China salinized soil mainly distributes in the western region.Chloride and sulfate were main ingredients of salinized soil.Screening and breeding salt-tolerant varieties is usually the most effective and economical way to develop and utilize salinized soil.Helianthus tuberosus L.is a perennial herb belongs to Helianthus of Compositae,also known as Jerusalem artichoke,and is one of economic crops that possesses the potential for development and utilization of salinized soil with characteristics of greater ecological adaptability,high biomass,strong ability of reproducing and resistance.In order to screen salt tolerance strains of Jerusalem artichoke and to explore the salt resistant physiological mechanism,we used two kinds of neutral saltneutral salt（NaCl and Na₂SO₄）to simulate the saline soil environment of western China.By measuring different genetic background of 12 Jerusalem artichoke strains’ seedlings indexs of emergence rate,agronomic traits,gas exchange characteristics,chlorophyll fluorescence characteristics,and used the method of fuzzy membership function for evaluation of salt resistance,we screened salt resistant Jerusalem artichoke strains.Then,we took strains of salt resistance and salt sensitive as research materials,used the determination indexs of agronomic traits,physiological and biochemical,gas exchange characteristics,chlorophyll fluorescence characteristics,Na+ and Cl-ion content under salt stress,investigated the physiological mechanism of Jerusalem artichoke strains resistant to salt,the main results were as follows:（1）The plant height,leaf area,crown shape indexes of different strains Jerusalem artichoke were suppressed under salt stress.Salt stress would damage Jerusalem artichoke photosystem II（PS Ⅱ）in different degree,salt stress inhibited the Jerusalem artichoke germination rate.Similarly,the plant photosynthetic characteristics would also be affected,and then inhibited biomass accumulation.According to the clustering results,12 strains of Jerusalem artichoke were divided into two groups: salt tolerance strains were LZJ119,LZJ028,LZJ110,LZJ111,LZJ026 and LZJ034,salt sensitive strains were LZJ047,LZJ003,LZJ017,LZJ041,LZJ044 and LZJ051.（2）Salt-tolerant Jerusalem artichoke strains（LZJ028 and LZJ119）had higher net photosynthetic rate than salt sensitive Jerusalem artichoke strains（LZJ044 and LZJ017）under salt stress,what’s more,theirs PS Ⅱ electron transfer condition and reaction center were damaged slight ly.Salt tolerance and sensitive Jerusalem artichoke resisted stress by improving activity of superoxide dismutase（SOD）and increasing osmotic regulation substances.In addition,salt tolerance strains were likely to compartmentalize harmful ions（Na+ and Cl-）to the stems and roots to reduce the damage of salt.Salt tolerance strains had stronger ability of osmotic adjustment than the salt sensitive strains.In conclusion,we screened 6 salt resistant strains LZJ119,LZJ028,LZJ110,LZJ111,LZJ026 and LZJ034.We found that salt resistant strains improved the resistance by compartmentaling harmful ions to stem,increasing osmotic regulation substances and enhancing photosynthetic organ patience.Our research results not only assist in selecting a batch of Jerusalem artichoke strains suitable for salinized soil,but also reveal the physiological regulatory mechanisms of salt resistant,then provide theoretical basis and technical support to using Jerusalem artichoke to develop and repair saline soil of western China.