Quantifying the effects of drought stress on cucumber genotypes differing in membrane integrity

Abstract: Cucumber yield is profoundly influenced by soil moisture, with drought representing a pivotal factor. This study evaluated four cucumber lines (CBECS-37, CBECS-38, CBECS-19, and CBECS-7) within a split-plot experimental design comprising four replications. Irrigation occurred once every seven days, spanning from sowing to the flowering stage. Drought stress was imposed at two critical stages: from flower bud initiation to harvesting (withheld irrigation for 25 days) and from flowering to harvesting (withheld irrigation for 15 days). Morphological and physiological parameters, including plant height, primary branch count, days to first male and female flower appearance, total soluble solids (TSS), relative water content (RWC), chlorophyll content, leaf electrolyte leakage, and malondialdehyde, were assessed 15 days after drought stress. Results indicated greater membrane damage during the flower bud initiation to the harvesting stage (404.5%) compared to the flowering to the harvesting stage (304.6%). Thus, drought stress during flower bud initiation to harvesting was more critical. CBECS-7 demonstrated the highest tolerance to drought conditions, displaying superior outcomes in primary branches, plant height (20.6%), chlorophyll a (16.7%), chlorophyll b (53.4%), total chlorophyll (26.7%), and RWC (6.7%). CBECS-7 exhibited increased chlorophyll content, enhanced photosynthetic activity, robust vegetative growth, and prolific flower and fruit production. These findings establish CBECS-7 as a drought-tolerant line during flower bud initiation to harvesting. In conclusion, this study underscores the critical nature of the flower bud initiation to the harvesting stage and identifies CBECS-7 as a drought-tolerant cucumber line.