Characterization of a Soybean (Glycine max L. Merr.) Population for Germination and Seedling Root Traits under Water Stress

Abstract

Dry soil conditions at soybean planting results in poor stand establishment, which often necessitates replanting. We conducted a study to identify soybean genotypes that can maintain germination rates and possess better root morphology under water stress. We tested 41 Plant Introductions (PI) for germination and seedling root traits under controlled environmental conditions at five water potentials: 0.00, −0.27, −0.54, −0.82, and −1.09 MPa (no, low, mild, severe, and extreme water stress, respectively). The same genotypes were tested for emergence and seedling root traits under field conditions in South Carolina (2021 and 2022) and North Carolina (2022). Among the 41 genotypes evaluated, PI 398566 and PI 424605A maintained higher germination percentages (≥63%) under water stress. The same genotypes were ranked among the top 15 genotypes for root traits (total-root and fine-root (diameter between 0.25 and 0.50 mm) length, surface area, and/or volume) under water stress. Furthermore, they had relatively higher emergence percentages under field conditions (≥35% under dry soil conditions). The superior genotypes identified in this study (PI 398566 and PI 424605A) that had better germination and root morphology under water-stress and no-stress conditions and better emergence would be useful for developing varieties with drought tolerance during the emergence phase.