Missouri farmers need soybean varieties capable of producing high yields even under less-than-optimal field conditions. Improving drought tolerance will aid in maintaining yields under reduced water availability and potentially increase yield if water availability is maintained. Field-based high-throughput screening for soybean WUE is only possible using surrogate measures. The most promising approach to accomplish this is the use of stable isotope techniques.

We expect that the direct application of the stable isotope techniques in the soybean breeding program, together with the mechanistic understanding of the traits, will position Missouri soybean breeders at the forefront of breeding for greater water use efficiency and yield.

The study of the physiological traits underlying the differential WUE between genotypes may also lead the discovery of new and simple approaches to select for more WUE soybean lines.