Stain Resistance Screening And Physiological Characteristics Analysis Of Jiangxi Black Sesame Varieties

Sesame is an important oil and cash crop in China,and waterlogging is the main ecological factor affecting sesame production.In Henan,Anhui,Jiangxi,Hubei and other major sesame producing areas,continuous rainfall or heavy rain weather causes soil water supersaturation,and lasts for a long time,resulting in a significant decrease in sesame yield.In this experiment,52 black sesame germplasm resources were selected,and pot waterlogging experiments and field waterlogging experiments were set up to determine the growth and development,yield and quality,physiological and biochemical indexes of sesame,to clarify the difference of WPA tolerance among different black sesame varieties,and to comprehensively select waterlogging-resistant,high-quality and high-yield varieties.The main results are as follows:(1)Fifty-two black sesame germplasm were subjected to pot waterlogging stress for 7 days at seedling stage,and the seedling survival rate,plant height,root length,aboveground and underground biomass,SPAD value and root-shoot ratio were measured.Through cluster analysis,52 sesame varieties were divided into three types:waterlogging tolerant varieties,moderately waterlogging tolerant varieties and waterlogging sensitive varieties.Among them,Poyang Black,Xingzi Black Sesame,Sesame(ZZM2834),Jinshajiang Black Sesame,17-50,17-61-1,etc.are 6waterlogging-resistant varieties;Hemp,Ganzhi 14,Zhongzhi 35,WZM-2,WZM-5 and17-119 are sensitive to waterlogging,while the other 30 varieties are moderately waterlogged-tolerant.(2)The effects of waterlogging stress on 11 agronomic characters of yield and yield components of black sesame at seedling stage showed that plant height,number of capsules per plant and number of grains per capsule were positively correlated with1000-grain weight and yield per plant,while the height of initial capsule and the length between empty shoots were negatively correlated with 1000-grain weight and yield per plant.Cluster analysis can divide 52 black sesame varieties into 3 groups.Among them,Group I is a high-yield group whose yield is less damaged by waterlogging at seedling stage,including Poyang Black Sesame,Xingzi Black Sesame,17-50,17-5-2 and 17-62.(3)The analysis results of 14 quality indexes of black sesame by waterlogging at seedling stage showed that the three principal components,sesamin,heptadecenoic acid and stearic acid,had the greatest influence on sesame quality after waterlogging.After standardized conversion of 14 quality traits,52 black sesame varieties were classified into 3 categories by systematic clustering.The third category contains 10 germplasm resources.The black sesame of this category is the least affected by waterlogging at seedling stage,with the highest comprehensive quality score,better quality,low content of crude fat,stearic acid and oleic acid,high content of linoleic acid and linolenic acid,etc.A comprehensive evaluation model was established for sesame quality indicators,and after the original data were standardized,the comprehensive quality scores could be obtained.The top five varieties with the highest comprehensive quality scores were WZM-4,Xingzi Black Sesame,WZM-10,Nanchang Black Sesame and Poyang Black Sesame.(4)The waterlogging-tolerant black sesame varieties(Poyang Black and Xingzi Black Sesame)and waterlogging-sensitive black sesame varieties(Jinhuangma and Zhongzhi No.35)selected by waterlogging at seedling stage were tested for different waterlogging durations.Under waterlogging stress,the total root length,taproot length,root surface area and root volume of black sesame seedlings with different WPA tolerance significantly decreased,while the average root diameter significantly increased,and the root activity decreased with waterlogging time.Moreover,the root morphology and root activity of waterlogged sensitive sesame increased more slowly than that of waterlogged tolerant sesame,and it also recovered slowly after waterlogging returned to normal management for 3 days.The activities of antioxidant enzymes SOD,POD and CAT increased in the early stage of waterlogging stress,and the accumulation of MDA in waterlogging-tolerant sesame Poyang Black and Xingzi Black sesame was less than that of waterlogging-sensitive sesame Jinhuangma and Zhongzhi 35.Osmotic regulators such as proline,soluble sugar and soluble protein maintain sesame seedling leaves against waterlogging stress,among which waterlogging-tolerant sesame accumulated more quickly than waterlogging-tolerant sensitive sesame.