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.