Abstract

Producers desire varieties that consistently perform with high yields and end-use qualities. Unlike easily recognized average yield improvements, yield stability over time is less examined, especially when considering the role of breeding relative to other factors like management and changing climatic conditions. Our study system was a 70-year historical dataset from which we estimated the year-over-year stability of Triticum aestivum, winter wheat varieties released by Montana's Agricultural Experimental Station. We examined yield stability within six locations representing diverse growing conditions across Montana and found evidence that breeding has improved stability at specific locations and not at others. Newer varieties showed improved year-over-year stability at locations that tended to have the lowest yields and more extreme weather conditions, reflecting that year-over-year stability has a genotype-by-environment component. We examined the role of climatic conditions, including temperature and rainfall to understand if reduced climatic variability was driving patterns of improved stability at these sites. However, the impact of breeding remained, or became evident when accounting for climatic variables. Together, these findings suggest that breeding's strong selective pressures improve second order traits.