Morpho-physio-biochemical responses of uncharacterised vegetable-type soybean (glycine max l.) breeding lines under drought stress

Title : Morpho-physio-biochemical responses of uncharacterised vegetable-type soybean (glycine max l.) breeding lines under drought stress

Abstract:

Traditional breeding focuses on yield trait selection for crop improvement under drought stress. However, integrating physio-biochemical screening is essential for identifying drought-tolerant vegetable-type soybean breeding lines. In 2020, a breeding programme involving seven genotypes in a diallel cross was initiated, and Griffing’s combining ability analysis identified AGS354 × UVE17 as a good specific combiner. Therefore, this study evaluated the physiological, biochemical, growth, and yield responses of eight uncharacterised vegetable-type soybean F₄ breeding lines derived from a cross between parents, AGS354 × UVE17, under drought stress. The parental lines and eight F₄ progeny lines (2.1/1, 2.12/2, 2.3/1, 2.3/2, 2.3/3, 2.5/1, 2.6/2, and 2.6/3) were subjected to 30% soil water holding capacity (30% WHC). Physiological and biochemical traits, including pigments, relative water content (RWC), total soluble sugars (TSS), proline, electrolyte leakage (EL), malondialdehyde, total phenolics, carotenoids, and reduced glutathione (GSH), were analysed to assess photosynthetic efficiency, osmotic adjustments, membrane stability, and antioxidant capacity. Significant genotype × treatment interactions were observed for several traits, indicating genotype-specific drought responses. Genotypes 2.12/2, and 2.3/1, 2.3/3, and 2.5/1 exhibited drought tolerance through enhanced osmotic adjustment, characterised by increased proline and TSS accumulation, maintenance of chlorophyll content and RWC, and low yield reduction under stress. In contrast, genotypes 2.6/2, 2.6/3, and the parental line UVE17 showed notable (p < 0.05) reductions in growth and yield traits, accompanied by low TSS accumulation and impaired physiological performance under drought stress. These findings provide insight into the mechanisms underlying drought susceptibility and tolerance in the current vegetable-type soybean breeding populations. Further studies should test adaptability and stability of 2.12/2, and 2.3/1, 2.3/3, and 2.5/1 progeny lines across different locations and years under drought stress.

Biography:

Dr. Jeremiah Hlahla is a plant physiologist specializing in crop stress physiology. He obtained his PhD in Botany from the University of the Free State (UFS) in 2025 and is currently a postdoctoral research fellow under the SARChI Chair in Disease Resistance and Quality in Field Crops at UFS. His research focuses on the physiological and biochemical responses of legumes to drought stress to identify stress-tolerant genotypes for crop improvement. He has received several academic awards, including the E.M. van Zideren Bakker Award, the Plant Science Award, and the SAAB Best Physiology Poster Award. His research has been published in leading international journals.