Impact of Drought Stress on Fatty Acid Composition, Oil and Protein Content, and Yield of Soybean Genotypes

Abstract

As global warming intensifies, drought stress has emerged as a major abiotic factor limiting soybean ( Glycine max L.) production. A primary objective of sustainable agriculture is the identification of drought‐tolerant genotypes and the implementation of breeding programs to develop resilient cultivars. This study evaluated the effects of drought stress on fatty acid composition, oil content, and protein yield across diverse soybean genotypes. The experiment consisted of four irrigation treatments during the 2023 and 2024 growing seasons: cessation of irrigation at flowering (T1), at pod formation (T2), and at pod filling (T3), alongside a fully irrigated control (T0). Oil content ranged from 12.9% (G9, T1) to 19.0% (G2, T0), while protein content ranged from 26.1% to 39.6%. Higher protein content was observed in the second year. Oil and protein contents were generally higher under T1 than T2, likely due to earlier activation of drought‐response mechanisms. The highest oil yield was 675.0 kg/ha (G2) in 2023 and 494.0 kg/ha (G9) in 2024. Similarly, peak protein yields were 1453.9 kg/ha (G2) in 2023 and 1993.6 kg/ha (G9) in 2024. Oil quality, measured by polyunsaturated fatty acid content, was highest in G8 (86.2%), closely followed by G9 and G10 (86.1% each). Genotype G9 demonstrated superior performance for oil and protein yield and oil quality. Therefore, G9 may be recommended as a promising parental line for future hybridization and breeding programs. These findings highlight the need to integrate drought‐tolerant traits into breeding programs to sustain soybean cultivation in water‐limited environments and to select varieties based on oil and protein yields and fatty acid profiles.