Study on early identification method of droughttolerance of mungbean cultivars

【Objective】 A method for identifying drought-tolerance of mungbean varieties was discussed in order to provide a theoretical basis for drought-tolerance breeding of mungbean.【Method】 A simple method of germination rate at 24h-after-water-absorption was used and verified to investigate mungbean drought-tolerance.The drought-tolerance of 25 mungbean germplasms was graded according to seed germination rate at the germination stage,and then in pot water-control trails at vegetative growth stage and reproductive growth stage.【Result】 It indicated that there were significant differences in drought-tolerance among mungbean materials.Water absorption made no difference to drought-tolerance.However,germination rate of 24 h-after-water-absorption and drought-tolerance were closely correlated.Seedling branch root number,main root length and root dry weight had significant(P0.05) or highly significant positive correlation(P0.01) with drought-tolerance.Under repeated stress of supplying water for 24 h after germination and then no water for 24 h,the survival rate of drought-tolerant cultivars was higher than that of ordinary ones.At the vegetative growth stage,temporary wilting(under soil moisture of 9% to 11%)treatment led to leaf wilting of ordinary cultivars,with reduced plant height,stem diameter and leaf area.Among the traits,the changes of stem diameter and leaf area were highly significant.During the reproductive growth stage,temporary wilting induced significantly lower root biomass and branch biomass in ordinary cultivars.When moved to the seed filling stage,ordinary cultivars wilted without recovery.On the contrary,the drought-tolerant cultivars still maintained ability to grow.【Conclusion】 These results indicated that 24 h-germination-rate of mungbean seeds could be used as a method in drought resistance identification and screening.