Effects Of NaCl Stress On Seed Germination Andphysiological And Biochemical Of Seedling In Chenopodim Quinoa

As a halophyte,Chenopodium quinoa could grow in the soil with a certain concentration of salt.It had high nutritional,medicinal,ornamental and economic value,which leaded to a wide market prospect.Soil salinization was one of the main causes of soil degradation,which had become a global ecological problem.In this experiment,the effects of salt stress on a series of physiological and biochemical indexes at the seed gemination and seedling growth stage of four Chenopodium quinoa germplasm had been studied under the treatment with 0?100?200?300?400 mmol/L NaCl solution respectively,in order to investigate and reveal the changing mechanism of in the process of salt tolerance.Moreover,four Chenopodium quinoa germplasm were sorted according to their salt tolerance by the weighted membership function method and screened out the best and the worst to discuss the role of Na+/H+ antiporter in the salt tolerance,further elaborated the mechanism of salt tolerance from the perspective of molecular,in order to provide a theoretical basis for selecting and evaluating the salt tolerant germplasm of Chenopodium quinoa.The main research results showed as follows:(1)With the increase of NaCl concentration,the relative salt damage rate of four Chenopodium quinoa germplasm continually rised,on the contrary,the germination rate,germination potential,germination index,radical length and hypocotyl length were inhibited in different degree.The impact was little at low salt concentration(0-200mmol/L),while significantly enhanced at high salt concentration(300-400mmol/L).(2)The correlation analysis between germination indexes and NaCl concentration showed that different quinoa seeds had no effect on the relative direction between germination indexes and NaCl concentration,but had a greater impact on the strength of the correlation between them.(3)In germination period,0-200mmol/L NaCl stress caused little impact on soluble protein content,peroxidase(POD)activity,ultra superoxide dismutase(SOD)activity on four Chenopodium quinoa germplasm.When the concentration increased to 300 mmol/L,significant effect will be produced in each index,which JQ126 increased the maximum.300mmol/L NaCl was a suitable concentration for identifing the salt tolerance of four Chenopodium quinoa germplasm(4)The results of comprehensive evaluation for salt tolerance in germination period showed: the salt tolerance of JQ126 was the best and the salt tolerance of JQ130 was the worst in four Chenopodium quinoa germplasm.Compared with JQ130,JQ126 had higher germination rate,germination potential,germination index,soluble protein content,POD activity and SOD activity under NaCl stress.(5)At seedling stage,with the increase of NaCl concentration,the relative conductivity of four Chenopodium quinoa germplasm continually rised,but different seeds showed different trends by prolonging the stress time.Under short-term salt stress,the chlorophyll a,chlorophyll b and total chlorophyll content increased at first and decreased subsequently with the increase of NaCl concentration,but with the extension of stress time,the chlorophyll of different seeds presented different trends.(6)Under different stress time,the soluble protein content of four Chenopodium quinoa germplasm at seedling stage showed different trends with the increase of NaCl concentration.However,the soluble protein content presented a downward trend at different NaCl concentration.(7)At seedling stage,the SOD activity,CAT activity,SOD activity and MDA content of four Chenopodium quinoa germplasm changed more complicated at different NaCl concentration and different stress time,without certain regularity.(8)The results of comprehensive evaluation for salt tolerance at seedling stage showed: the salt tolerance of four Chenopodium quinoa germplasm ranked in the order of JQ129,JQ130,JQ126,JQ125.Compared with JQ125,the SOS1 A gene and NHX1 gene of JQ129 had the features of quickly starting,highly up-regulated expression under 400mmol/L NaCl treatment.(9)The salt tolerance of four Chenopodium quinoa germplasm performed different between germination period and seedling stage,only JQ129 showed stronger salt-tolerance at both germination period and seedling stage.