Evaluating the effects of flooding stress during multiple growth stages in soybean

Authors: FLETCHER, ELIZABETH - VIRGINIA TECH; PATTERSON, ROBERT - NORTH CAROLINA STATE UNIVERSITY; DUNNE, JEFFREY - NORTH CAROLINA STATE UNIVERSITY; SASKI, CHRISTOPHER - CLEMSON UNIVERSITY; Fallen, Benjamin

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2023
Publication Date: 4/27/2023
Citation: Fletcher, E., Patterson, R., Dunne, J., Saski, C., Fallen, B.D. 2023. Evaluating the effects of flooding stress during multiple growth stages in soybean. Agronomy Journal. 13(5), 1243. https://doi.org/10.3390/agronomy13051243.
DOI: https://doi.org/10.3390/agronomy13051243

Interpretive Summary: As the occurrences of extreme weather are on the increase due to a changing climate, flooding has become a more common problem. In soybean, flooding is the second most damaging abiotic stress, only behind drought, that farmers must contend with today. The standing water and water-logged soils deprive plants of the necessary light, oxygen, and carbon dioxide required for growth. Symptoms of flood stress in soybeans can range from a reduction of plant growth, yellowing of the leaves, defoliation, and the most severe – plant death. The growth stage at which flooding occurs can also have a large impact on the plants ability to respond and adapt to stress. Germination is a crucial stage as it establishes the plant stand and ultimately the yield potential. One of the most sustainable solutions to combat flood damage in soybean is the development of flood tolerate varieties. This study was conducted to evaluate soybean varieties for the response to flood stress at three critical growth stages for production – germination, early vegetative growth, and early reproductive growth. The results demonstrated that stress imposed by flooding had a significant effect on soybean yield for each growth stage studied. The average germination rate over the various treatments ranged from 95% to 46%. Despite the poor germination rates after the extended flood treatments, the flood tolerant varieties were able to maintain a germination rate of > 80% after 8 hr of flooding, meeting the required rate to optimize yield. Imposing flood stress during early reproductive growth also resulted in significant differences between the tolerant and susceptible varieties, and the controls. The flood tolerant genotypes maintained a mean biomass approximately 10% greater than the susceptible varieties under the same treatments. Varieties with the highest level of flood tolerance continually outperformed the susceptible varieties. These results suggest that the varieties identified as flood tolerant can be used in future efforts to improve resiliency during these crucial growth stages and overall improve yield under flood conditions.

Technical Abstract: Flooding is becoming an increasing concern as the occurrences of extreme weather are on the rise due to a changing climate. This study was conducted to evaluate soybean genotypes for the response to flood stress at three critical growth stages for production – germination, early vegetative growth (V1 and V4), and early reproductive growth (R1). The results demonstrated that stress imposed by flooding had a significant effect on soybean yield for each growth stage studied. The average germination rate over the various treatments ranged from 95% to 46%. Despite the poor germination rates after the extended flood treatments, the flood tolerant genotypes were able to maintain a germination rate of > 80% after 8 hr of flooding, exceeding the minimum germination rate needed to optimize yield. Imposing flood stress at the V1 growth stage also resulted in significant differences between the tolerant and susceptible genotypes, and the controls. The flood tolerant genotypes maintained a mean biomass approximately 10% greater than the susceptible genotypes under the same treatments. Genotypes with the highest level of flood tolerance continually outperformed the susceptible genotypes. These results suggest that the genotypes identified as flood tolerant can be used in future efforts to improve resiliency during these crucial growth stages and overall improve yield under flood conditions.