Physiological traits reveal potential for identification of droughttolerant mungbean[Vigna radiata (L.)Wilczek] genotypes undermoderate soil-moisture deficit

Abstract

Canopy temperature is an important physiological trait usedfor screening drought tolerance in several crop plants.Mungbean being often exposed to post-flowering drought,we evaluated a set of 48 genotypes for variability in post-flowering canopy temperature and its association with roottraits and other physiological parameters contributing todrought tolerance under soil-moisture deficit stressconditions. Overall, canopy temperature depressionrevealed significant association with seed yield. Root traitslike number of lateral branches and dry root weight exhibitedsignificant negative correlation with canopy temperature.Leaf SPAD readings were positively associated with grainyield and most of the high SPAD genotypes maintainedhot canopies under drought. Some genotypes withcontrasting variation in SPAD levels (DMG-1050 and SML-1628) maintained their photosystem PSII health at par.Moreover, cool canopy was no guarantee for better PSIIhealth or vice versa. This study identified some cool canopygenotypes (VC-6173-C, IC-325770 and ML-2082) and agenotype (DMG-1050) with novel trait combinations likehigh SPAD and better PSII health despite high canopytemperature which can be used as donors in mungbeanbreeding programs. Present study explores geneticvariation in these adaptation traits contributing to plantperformance under soil-moisture deficit stress conditionsand potential of physiological breeding approaches forgenetic enhancement of this legume crop