Evidence of Local Adaptation in Breeding Wheat for Weed-Competitive Ability.

Although the effect of local adaptation is well documented in evolutionary biology, few studies have quantified the impact of local adaptation in plant breeding. Decentralized plant breeding programs have the potential to harness local adaptation for crop improvement, but the effectiveness of such models is understudied. We quantified the capacity of a decentralized participatory breeding program to improve weed-competitive ability in spring wheat. After two years of selection for early vigor and survival under weed pressure, farmers across diverse environments in the northeastern United States improved weed-competitive ability. Selected populations reduced weed biomass by 11.46% compared with unselected controls. Developed spring wheat populations also showed evidence of local adaptation. When grown on farms where they were selected, “local” populations exhibited 9.35% higher weed-competitive ability than the “introduced” populations selected on other farms. Moreover, the magnitude of gains in selection for weed-competitive ability depended on the similarity between selection and testing environments. This study concluded that weed-competitive ability and its correlated trait of early vigor show local adaptation, and can benefit from highly decentralized breeding. Furthermore, decentralized breeding programs should carefully choose testing environments when measuring gains in selection. To capture the full potential of locally adapted breeding lines, testing environments should have high genetic correlation with the selection environment.