Effect of Water Deficit Stress on the Growth and Photosynthetic Characteristics of Okra Plant

Water deficit stress significantly impacts the yield and quality of okra, an important edible and medicinal vegetable. Understanding the physiological adaptation mechanisms of okra under drought conditions and identifying effective adaptation strategies are critical to its sustainable development. This study examined the phenotypic traits, photosynthetic characteristics, and chlorophyll fluorescence parameters of okra seedlings subjected to continuous natural drought for 0, 5, 7, 15, and 20 days. The results revealed that drought dramatically inhibited the growth and photosynthetic processes of okra seedlings, as evidenced by reductions in chlorophyll a, chlorophyll b, carotenoids, gas exchange parameters, apparent quantum efficiency, light compensation point, light saturation point, and several chlorophyll fluorescence metrics. Conversely, water deficit stress significantly enhances root development, as evidenced by increases in total root length, surface area, root tips, and root biomass. Notably, drought stress also elevates the chlorophyll a/b ratio, intercellular CO 2 concentration, dark respiration rate, and maximum net photosynthetic rate. These findings illustrated the complex physiological responses of okra to water deficit stress and highlighted a tradeoff between aboveground growth inhibition and enhanced root system development, thereby facilitating the plant’s adaptation to water deficit.