Soybean varieties vary in their seed protein content and in drought responses. Drought typically lowers yield, but some varieties have more stable seed composition than others. This project investigated the interaction between drought responses, nitrogen metabolism, and seed protein. Year 1 had the mildest drought during the early seed fill period, and year 3 had the most severe drought. In year 4, drought was moderate, but in year 2, we experienced a more severe
drought during early seed fill, but this was followed by Hurricane Florence and more extremely wet weather during later seed fill, reducing the impact of the drought. The severe drought in year 3 occurred during the critical seed filling period. In the year with mildest drought, a few genotypes had lower seed protein content in the drought-stressed plots, while others had stable seed protein concentration. However, in the year with severe drought, most genotypes had
increased seed protein concentration in the drought stressed plots. Seed protein responses depend on the severity of stress, and seed protein had more variation among genotype in moisture stress responses than either yield or oil concentration. Based on these results, it may be possible to improve soybean seed protein responses to drought stress through soybean breeding. However, a negative tradeoff between yield responses and seed protein concentration responses to drought was observed.