Studying the Relationship between Water Use Efficiency and Yield in Elite Soybean Lines in Alabama.

In order to meet future food demands of an estimated 9 billion world population in 2050 and in a changing climate crop yields will need to greatly increase. With global climate change, the environments in which major crops are grown are expected to suffer through unpredicted drought seasons . Though soybean (Glycine max.) cultivars with high water use efficiency are well known and can sustain through early or late season drought, it is less understood whether these cultivars will meet future yield demands, as high WUE has been related with lower yields under well water conditions. Understanding the genetic and environmental factors underlying yield, yield components and water use efficiency can help better predict routes for crop improvement. Within this study, 14 commercial cultivars adapted to different regions of the Midwest and Southeast were grown in two locations in Alabama. Water use efficiency was inferred using carbon isotope discrimination as this relationship has been well studied in soybean. During the growing season, physiological measurements were taken such as photosynthesis measurements and leaf area index. At harvest yield components such as HI and hundred seed weight were calculated. Between locations, yield, photosynthesis, conductance and WUE varied suggesting environmental factors in WUE and yield variations. Comparisons of carbon isotope discrimination and inter-cultivar variations will be analyzed for further understanding of GxE interactions affecting WUE and yield.