SUDHAKAR, PYOHAN, Y2018-08-132018-08-132017http://krishikosh.egranth.ac.in/handle/1/5810064207D5506The experiment entitled “Screening of Blackgram (Vigna mungo L. Hepper) genotypes for Physiological efficiency and Drought tolerance” was conducted at crop physiology laboratory (Lab study) and dry land farm (Field study), S.V. Agricultural College, Tirupati. Forty five blackgram genotypes obtained from RARS, LAM, ANGARU were screened for heat tolerance using the standardized Thermo Induced Response (TIR) protocol, where seedlings were exposed to gradual and challenging temperatures in environment chamber. Among the 45 genotypes, top ten genotypes (KU-12-55, LBG-623, LBG-680, NDU-12-300, LBG-685, KU-12-14, LBG-645, KU-12-37, TBG-104, KU-12-13) having higher heat tolerance in terms of higher seedling survival and less reduction in root and shoot growth were selected along with two genotypes having lower heat tolerance viz., LBG-752, LBG-20. A field trail was conducted with two irrigation treatments (Control and stress) and 12 blackgram genotypes replicated thrice in split plot design. Moisture stress was created at pod formation stage i.e for a period of 15 days starting from 40 to 60 DAS. Sufficient moisture stress was created among stress treatments leaf relative water content was reduced by 25.2 per cent. xxii Morphological characters like plant height, number of nodules, leaf area, total dry matter, physiological parameters, drought tolerance traits viz., rooting abilities, Water Use Efficiency (WUE), Relative Water Content (RWC), chlorophyll Stability Index (CSI), Proline (Osmoregulant), Super oxide dismutase, Perioxidase (POD) (Antioxidant enzyme) and Nitrate reductase (NR) and yield related parameters were examined. Growth and physiological traits viz. plant height, crop growth rate (CGR), net assimilation rate (NAR), leaf area index (LAI) and leaf area duration (LAD), WUE traits (SLA, SCMR), other drought tolerant traits viz., CSI, RWC, yield and HI significantly reduced under moisture stress conditions compared to irrigated control, where as proline, POD and SOD were increased. The genotypes TBG-104, KU-12-13, KU-12-37 and LBG-623 maintained higher leaf area, dry matter and higher physiological traits viz., CGR, NAR, LAI and LAD compared to other entries under irrigated as well as stress conditions. These genotypes also recorded higher drought tolerance interms of WUE traits i.e moderate SLA and high SCMR, higher chloroplast stability (CSI), higher accumulation of proline and SOD enzyme, which denotes the efficiency of these genotypes in conserving water as well as maintaining osmoregulation and cell membranes integrity under drought condition. Genotypes TBG-104, KU-12-13 and KU-12-37 recorded higher mean root length and low root dry weight and hence maintained higher tissue water content compared to other genotypes. TBG-104, KU-12-13 and KU-12-55 which maintained higher growth, physiological and drought tolerance attributes also recorded higher HI, yield and its components followed by LBG-680, KU-12-37 and LBG-623. The genotype NDU-12-300, KU-12-14 and LBG 645 recorded lower yields under imposed moisture stress conditions as these genotypes recorded lower physiological attributes and drought susceptibility characters. TBG-104, KU-12-13 and KU-12-37 recorded lower percent yield loss in terms of higher drought tolerance index. The genotypes TBG-104, KU-12-13 and KU-12-55 were superior in terms of physiological efficiency, heat and moisture stress tolerance with high seed yield. These genotypes can be fit in rainfed cultivation or can be used as donor source for development of drought tolerant blackgram genotypes through conventional as well as molecular breedingen-USnullThesis