Estimation of Water Use Efficiency and Osmolyte accumulation to Evaluate Drought Stress Tolerance in Mulberry

The present study was under taken to assess the drought stress tolerance in four mulberry genotypes and three varieties. Four months old mulberry plants were subjected to three water regimes viz., 100% PC, 50% PC, 25% PC for 30 days. Chlorophyll Stability Index, intrinsic Water Use Efficiency and osmolyte accumulation (proline content) were estimated before imposing drought stress and 30 days after drought stress. WUEi and proline accumulation was increased, while CSI, carbohydrate and protein contents were found to be decreased as severity of drought stress progressed. Mulberry genotype, MI-0425 was found to be drought tolerant with higher WUEi (4.13 mmol CO2 mol-1 H2O) and proline accumulation (8.54 μg g-1). This line also showed lesser protein degradation at severe drought stress. The genotype MI-0613 recorded lower WUEi (3.18 mmol CO2 mol-1 H2O) and proline content (5.87 μg g-1) under severe drought stress. It also recorded severe reduction in yield (45.96%) under stress. Hence, MI-0613 was identified as a drought susceptible genotype. Variety V1 recorded higher CSI (77.68%) and carbohydrate (29.03 mg/g) and yield (95.48 g/plant) under both in moderate and intense water stress treatments. Hence, V1 was found to mitigate drought stress by maintaining higher CSI and carbohydrate content.