Quantifying the physiological, yield, and quality plasticity of Southern USA soybeans under heat stress

Authors: POUDEL, SADIKSHYA - Mississippi State University; ADHIKARI, BIKASH - Mississippi State University; DHILLON, JAGMAN - Mississippi State University; REDDY, K RAJA - Mississippi State University; Stetina, Salliana - Sally; BHEEMANAHALLI, RAJU - Mississippi State University

Submitted to: Plant Stress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2023
Publication Date: 8/5/2023
Citation: Poudel, S., Adhikari, B., Dhillon, J., Reddy, K., Stetina, S.R., Bheemanahalli, R. 2023. Quantifying the physiological, yield, and quality plasticity of Southern USA soybeans under heat stress. Plant Stress. 9:100195. https://doi.org/10.1016/j.stress.2023.100195.
DOI: https://doi.org/10.1016/j.stress.2023.100195

Interpretive Summary: Soybean growing seasons are becoming hotter, which is a potential threat to soybean production. To determine if soybean plants have the ability to adapt to hotter temperatures, ten soybean cultivars were grown under temperatures 4.6 degrees Celsius above the optimum during the time that plants were flowering and forming pods. In general, heat stress decreased stomatal conductance, specific leaf area, plant height, pod number, pod weight, seed number, seed weight, and protein content, but increased oil content. However, not all cultivars reacted the same, and the study identified some that performed better under heat stress. These cultivars could be used by growers in regions experiencing heat stress at flowering and pod set to improve yields. They can also serve as parents in breeding programs to develop more soybean lines that can yield well under hot climate conditions.

Technical Abstract: Temperatures above the optimum impact genetic potential and threaten soybean production. A sustainable food supply entails tolerant soybean cultivars grown to minimize the impact of heat stress on yield and quality. In this study, ten soybean cultivars were exposed to temperatures +4.6 degrees C above the optimum (32 degrees C) during the reproductive stage. Heat-stressed plants reduced stomatal conductance (11.3%), and specific leaf area (18%) compared to the control. Furthermore, heat-stressed plants showed a decline in plant height, pod number, and pod weight by 11.5%, 17.6% and 18.5%, respectively. Heat stress also reduced seed number by 4.2%, seed weight by 5.03%, and hundred seed weight by 1.1% per degree C increase in temperature. Oil content increased by 10% under heat stress, while protein content decreased by 2%. Our study demonstrated the potential impact of heat stress on phenotypic plasticity and identified cultivars that can yield high under hot climates.