Breeding wheat for weed-competitive ability: II. Measuring gains from selection and local adaptation

Authors: Kissing Kucek, Lisa; DAWSON, JULIE - University Of Wisconsin; DARBY, HEATHER - University Of Vermont; MALLORY, ELLEN - University Of Maine; DAVIS, MICHAEL - Cornell University; SORRELLS, MARK - Cornell University

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2021
Publication Date: 10/25/2021
Citation: Kucek, L.K., Dawson, J., Darby, H., Mallory, E., Davis, M., Sorrells, M. 2021. Breeding wheat for weed-competitive ability: II. Measuring gains from selection and local adaptation. Euphytica. 217. Article e203. https://doi.org/10.1007/s10681-021-02905-w.
DOI: https://doi.org/10.1007/s10681-021-02905-w

Interpretive Summary: Weeds reduce productivity in agriculture. Plant breeding may help develop crop varieties that are more competitive with weeds. We worked directly with farmers to select new wheat varieties with better competition. The resulting varieties of wheat reduced weed growth. We also tested whether the varieties would compete better with weeds on the farm where they were developed than other farms in a region. Due to large differences in weed presence among years and locations, more testing would be necessary to fully evaluate whether varieties performed better in certain locations.

Technical Abstract: 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 ability of a decentralized participatory plant breeding program to improve weed competitive ability (WCA) in organic spring wheat. On average, four farmers in the northeast United States enhanced competitive ability of selected genotypes by 11.46%. We also measured early vigor and canopy cover, traits correlated with weed competitive ability. Measured gains from selection for early vigor and early canopy cover, however, varied among testing environments. Gains in selection were highly related to the genetic correlation coefficient between selection and testing environment (r = 0.77 and r = 0.80 for early vigor and canopy cover, respectively). To accurately measure gains from selection for decentralized breeding programs, testing environments should be chosen that are similar to where selection took place. Inconsistent weed competition among site-years limited conclusions from the analysis of local adaptation for weed competitive ability. Detecting local adaptation in plant breeding, which typically uses a small number of selection cycles compared to evolutionary biology, requires many genotypes, environments, and years for adequate statistical power. The ecological complexity of the weed competitive ability further complicates experimental design and challenges the ability to measure local adaption.