Morpho-physiological and water use performance of soybean cultivars under drought stress at early growth stages

Abstract

Drought is an important environmental stress for soybean (Glycine max (L) Merr.), which frequently occurs under second-crop conditions in the Mediterranean region of Türkiye and negatively affects early plant growth. In this study, we investigated the effects of drought stress (soil water content maintained at a constant 50% field capacity) on the early growth stage (V3 stage) of different soybean cultivars (Ataem-7, BATEM Erensoy, Göksoy, and Lider). Twenty-seven-day-old soybean plants were exposed to drought stress for 20 days. Morphological (plant height, root length, seedling fresh and dry weight, root fresh and dry weight, and leaf area), physiological (leaf temperature, chlorophyll rate (CR), leaf relative water content (RWC), and electrolyte leakage (EL)), and water use (total water consumption (TWC), and water use efficiency (WUE)) traits were assessed. The results revealed a significant decrease in plant height, root length, leaf area, root and shoot fresh and dry weights, and RWC, and an increase in CR under drought stress. Although Lider and BATEM Erensoy exhibited better growth than the other cultivars under control conditions, their root and shoot growth decreased significantly under water stress. Notably, Ataem-7 presented a lower TWC and WUE difference between the drought treatment and the control, and this cultivar efficiently used water for dry matter production in the shoot and root parts. As a result, there were significant genotypic differences in drought susceptibility among the soybean cultivars, and Ataem-7 showed greater tolerance to drought than the other soybean cultivars did during the early growth stage.