Drought is considered the number one environmental factor limiting genetic potential of yield (Boyer 1982). In North Dakota, the western part of the state is characterized by low water conditions with an average of 10-16 inches of rain a year compared to the Red River Valley that
receives 20-22 inches of rain a year (nass.usda.gov). Lack of adequate water is one reason why soybean yields average only 30 bushels/acre in the west compared to the Red River Valley that
has soybean yields around 60 bushels/acre (NDSU variety trial data from multiple years). Also,
the need to preserve high yield potential in both well-watered and low-water conditions is fundamental to improving soybean production in the western part of North Dakota. Research has been ongoing for many decades exploring different physiological methods to overcome yield losses due to drought. However, many have proved to be elusive, or plants suffered poor agronomic performance during well-watered conditions (Sinclair et al 2007). Interestingly, research has shown that soybean plants that are able to maintain nitrogen fixation during drought conditions have less yield loss than other susceptible lines (Sinclair et al 2007, 2010). In addition, varieties have been bred that possess the sustained nitrogen fixation trait and still outperform check varieties in well-watered conditions, suggesting that this trait does not have a yield drag associated with it (Chen et al 2007). Although drought research is challenging, focusing on improvement of nitrogen fixation during drought conditions seems to be a
promising direction to explore to improve yields in the driest areas of North Dakota.