Existence of alternate defense mechanisms for combating moisture stress in horse gram [Macrotyloma uniflorum (lam.) verdc.]

Screening of horse gram (Macrotyloma uniflorum) core collection was carried out under moisture stress conditions in glass house and in poly ethylene glycol 8000 solutions with an osmotic potential of-0.15 MPa to-1.76 MPa after germination. However, selected 50 accessions from the above study were raised under controlled moisture stress conditions to analyze variations in the magnitude of different enzyme activities among the surviving accessions. RWC remained unaltered during moisture stress condition but alteration in the plant structure was observed. Catalase activity and superoxide dismutase increased during moisture stress condition, which varied among the contrasting accessions. However, reduction in polyphenol oxidase and ascorbic acid oxidase activity was observed. The observed difference in anatomy confirms the presence of mechanisms other than antioxidant enzymes. Based on the performance in varying moisture stress conditions, the contrasting D9 and D14 were selected for breeding programme while D13 is recommended as a suitable cultivar under both irrigated and rainfed conditions. Differential enzyme activity, reduction in total sugar production and structural compaction were observed as mechanisms of energy conservation in horse gram to resist moisture stress conditions.