Exploring Drought Tolerance in Okra Through Morpho-Physiological, Biochemical Characteristics and Yield Based Indices

Drought stress is one of the remarkable abiotic stress which causes substantial yield and economic losses across the globe in the changing climate scenario. Though, okra plants can grow well, it produces fewer pods under limited water conditions, with a direct correlation between water supply and yield. This study aimed to evaluate the drought tolerance of selected okra accessions by analysing various morpho-physiological and biochemical traits, with the goal of identifying the most promising genotypes for breeding programs focused on drought tolerance. In this study, initially, 24 okra genotypes were tested for drought tolerance under field conditions and further they were tested in a pot experiment with 50% field capacity. The least reduction in relative water content (RWC) under field trial was found in VRO 128 (4.58%), followed by VROR 106 (7.17%), while in the pot trial, it was the least in VROR 160 (11.09%), followed by VRO 128 (12.34%). Furthermore, VRO 128 demonstrated the highest increase in peroxidase (POD) activity (4.17-fold) in the field trial, followed by VROR 160 (3.65-fold), and similarly in the pot trial, VRO 128 showed the highest increase (2.36-fold), followed by VRO 160 (1.92-fold). Pot experiment revealed VROR 160 and VRO 128 show a comparatively lesser reduction in yield under drought stress (9.7%) in contrast to the control (10.5%). Hierarchical clustering of okra genotypes based on morpho-physiological, biochemical and yield characteristics, including photosynthesis rate, chlorophyll content, antioxidant activity (specifically peroxidase and catalase), lipid peroxidation, as well as the synthesis of proline and hydrogen peroxide under pot condition grouped the genotypes VRO 128, VROR 160, VRO 106, VRO 124, and VRO 221 into highly drought tolerant group. Furthermore, drought tolerance indices such as drought tolerance index (DTI), Mean productivity (MP), Geometric mean productivity (GMP) and rank sum analysis under both field and pot conditions, revealed that VRO 128 and VROR 160 are two standout genotypes. The root architecture analysis unveiled that VRO 128 and VROR 160 enhanced water uptake through increased root volume and root length, respectively under drought stress. Hence, the study exhibited that VRO 128 and VROR 160 have the potential for inclusion in breeding programs to produce drought-tolerant varieties due to their resilience to drought conditions and their strong genetic capacity for enhanced performance under drought stress.