Drought Tolerance Identification And Genetic Diversity Analysis At Germination Stage Of Mung Bean Germplasm

Drought is considered one of the most acute environmental stresses presently affecting agriculture and food production,and also causes a variety of hazards in crops.Seed germination is the premise to ensure the normal growth and development of plants,and soil moisture content plays a crucial role in seed germination,so drought tolerance at the germination stage is the key period to study drought tolerance of plants.In this paper,the drought tolerance of 168 mung bean germplasm resources was identified,and the levels of drought tolerance were classified.The germplasm resources with high tolerance and high sensitivity were screened out,and the genetic diversity was analyzed.The main results are as follows:(1)In this study,through the establishment of the drought tolerance identification system of mung bean at germination stage,it was determined that 11% concentration of mannitol solution was the optimal concentration for screening germplasm at germination stage of mung bean.(2)Principal component analysis found that the cumulative contribution rate of the first three principal component factors reached 81.84%,indicating that the first three independent principal components could represent the variation information of the 10 indexes.According to the comprehensive evaluation value D calculated by principal component analysis,168 mung bean varieties were divided into five grades according to the classification standard of drought tolerance: high tolerance,drought tolerance,medium tolerance,sensitivity and high sensitivity.Two germplasm with high tolerance and three germplasm with high sensitivity were screened.(3)There was a significant positive correlation between D value and relative germination rate,indicating that the relative germination rate could predict the drought tolerance of mung bean.(4)The genetic similarity coefficients of 90 samples ranged from 0.4186 to 0.9922,with an average value of 0.7051.At the genetic similarity coefficient of 0.63,90 mung bean germplasm resources were clustered into four groups.The first group(Ⅰ)had 18 germplasm resources,including high tolerance germplasm,drought tolerance germplasm and medium tolerance germplasm,accounting for 94.4%.The second group(Ⅱ)consisted of 6 germplasm,of which 4 germplasm were drought tolerant and medium tolerant,accounting for 66.6%.The third group(Ⅲ)consisted of 65 germplasm,including 1 high tolerance germplasm,18 drought-tolerant germplasm,31 medium tolerance germplasm,12 sensitive germplasm,and 3 high sensitivity germplasm.The fourth group(Ⅳ)only included one germplasm,YZ006,which was drought-tolerant.