Evaluation Of Salt Stress Tolerance In The Stage Of Seed Germination And Seedling Growth In Different Genotypes Of Amaranthus Hypochondriacus

Amaranthus hypochondriacus is a new grain-forage crop with high quality and strong salt tolerance,which has a great difference in salt tolerance among different genotypes.In order to select the germplasm resources and breeding materials with strong saline tolerance,the effect of salt stress on seed germination,seedling growth and physiological metabolism in 125 different genotypes of A.hypochondriacus resources were investigated.The main results are as follows:（1）125 different germplasm resources of A.hypochondriacus were germinated in 0mmol·L^-1（sterile water,CK）and 250 mmol·L^-1Na Cl solution.In this study,the seed germination traits including germination energy,germination rate,germination index,vigor index,radicle length and plumule length were investigated.The membership function and cluster analysis were used to comprehensively evaluate the salt tolerance of different genotypes of A.hypochondriacus.The results indicated that 250 mmol·L^-1Na Cl solution inhibited seed germination and growth of radicle and plumule,compared with the control group,germination energy,germination rate,germination index,vigor index,radicle length,plumule length and radicle-plumule ratio were decreased of all A.hypochondriacus genotypes,but there were great differences in the response of different genotypes to salt stress.Combined with the membership function value and cluster analysis,125 germplasm materials could be divided into three categories according to their salt tolerance:the first category was salt-tolerant germplasm,which contained 29 materials,and the average membership function ranged from 0.560 to 0.947;the second category was moderately salt tolerant germplasm,which contained 44 materials,and the average membership function ranged from 0.395 to 0.553;the third category was sensitive salt germplasm,which contained 52 materials,and the average membership function ranged from 0 to0.389.（2）Ahp1266 seedlings were treated with 0,75,150,225 and 300 mmol·L^-1Na Cl solution with Hoagland nutrient,respectively.The results showed that when salt concentration was 225 mmol·L^-1,the morphological and physiological indexes of Ahp1266were significantly different from the control group.Therefore,225 mmol·L^-1Na Cl was selected to evaluate the salt tolerance of A.hypochondriacus germplasm at seedling stage.（3）8 different A.hypochondriacus germplasms at germination stage with great difference in salt tolerance were used as materials,and their seedlings were treated with 0mmol·L^-1（Hoagland nutrient solution,CK）and 225 mmol·L^-1Na Cl solution.The results showed that there was a great difference in salt tolerance of 8 A.hypochondriacus materials in seedling stage.Under salt stress,the aboveground growth rate,aboveground biomass,underground biomass,blade length,blade width,blade area,blade perimeter,chlorophyll content and CAT activity of the seedlings were all decreased.The response of taproot and SOD activity to salt stress was not consistent among different genotypes.Taproot length of Ahp1279 and Ahp1230 showed a decreasing trend,but that of other genotypes increased significantly（P<0.05）;SOD activity of Ahp1409,Ahp1231 and Ahp1296 increased,while SOD activity of other genotypes decreased;POD activity was significantly increased in all genotypes（P<0.05）,and there were significant differences among different genotypes.（4）The salt tolerance in 8 different genotypes of A.hypochondriacus was different between germination and seedling stage.Salt tolerance in germination stage:Ahp1265>Ahp1266>Ahp1279>Ahp1409>Ahp1296>Ahp1231>Ahp1230>Ahp1241.Salt tolerance in seedling stage:Ahp1265>Ahp1296>Ahp1231>Ahp1266>Ahp1409>Ahp1279>Ahp1241>Ahp1230.