Yield variation, plasticity, adaptation, and performance ranking of winter wheat varieties across the environmental gradient of the US Pacific Northwest

Authors: Adams, Curtis; NEELY, CLARK - Washington State University; GRAEBNER, RYAN - Oregon State University

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2025
Publication Date: 2/21/2025
Citation: Adams, C.B., Neely, C., Graebner, R.C. 2025. Yield variation, plasticity, adaptation, and performance ranking of winter wheat varieties across the environmental gradient of the US Pacific Northwest. Crop Science. 65(1). Article e70018. https://doi.org/10.1002/csc2.70018.
DOI: https://doi.org/10.1002/csc2.70018

Interpretive Summary: The U.S. Pacific Northwest is a major wheat production region with widely ranging water availability across dryland and irrigated systems. Wheat breeders develop varieties in the context of this environmental gradient, ideally releasing varieties that can perform well across many sub-environments. But no quantitative evaluations have been made of wheat yield variation, plasticity, adaptation, and performance due to variety considering the entire gradient, useful for yield gap analysis and other applications. We sought to do this. Boundaries for expected yield of winter wheat varieties across the environmental gradient were characterized. Yield plasticity of 45 individual varieties were evaluated using the Finlay-Wilkinson regression approach, showing wide variation in responses. A simple statistical approach was successfully used to infer yield performance traits from the regression outputs. Analysis is also presented on wheat variety by environment interactions and club wheat.

Technical Abstract: The U.S. Pacific Northwest is a major wheat (Triticum aestivum L.) production region with widely ranging water availability across its dryland and irrigated cropping systems. There have been no evaluations of variation, plasticity, adaptation, and performance of wheat yield due to variety—collectively or individually—that consider the entire environmental gradient of the region, useful for yield gap analysis, informing breeding, and other applications. Our objectives were to provide these evaluations using a large variety trial dataset and an independent dataset. Using linear models covering site-averaged yields (x variable) from about 1.50 to 12.0 Mg ha-1, upper and lower yield boundaries due to differences in variety performance were characterized by the regression models y = 1.08x + 0.24 and y = 0.906x – 0.13, respectively. The accuracy and usefulness of these functions were validated by the close fit of an independent dataset. Yield plasticity and environmental adaptation of 45 individual wheat varieties were also evaluated using the Finlay-Wilkinson regression approach, which showed wide variation in varietal yield responses to environment and substantial differences in yield stability (i.e., variation around the yield trend). A limitation of this analytical approach has been that the regression coefficients are not directly useful for ranking varieties for yield performance across contrasting environments. A simple transformation procedure of the coefficients into a single metric was effective for rapidly providing such rankings. A limited analysis is presented quantifying the relative contributions of genotype (27 – 58% within sites), environment (84% across sites), and their interaction (5% across sites) on regional yields, as well as yield analysis of club wheat. In summary, this work provides useful research tools and a region-wide perspective on yield traits of Pacific Northwest wheat varieties.