International Winter Wheat Evaluation: Relationships among Test Sites Based on Cultivar Performance

Abstract

Effective exchange of germplasm and information amonng international researchers has been hindered by lack of information concerning similarities in biotic and abiotic stresses associated with cultivar selection and performance in production areas. Seventeen years of data from the International Winter Wheat Performance Nursery were used as a basis for defining and characterizing relationships among test sites. Average correlations of cultivar yields among 56 locations 30 countries were used as a basis for principal factor analyses. Varimax rotation was used to uniquely define factors. Seven factors adequately accounted for 63% of the variation in the dependence structure. The seven regions identified were considered as mega‐environments for winter wheat (Triticum aestivum L.) production. Principal factor analysis was used to further subdivide locations within five of these mega‐environmental regions. Factor coefficients were correlated with location means for yield, heading and ripening dates, grain‐fill duration, and winter survival. The correlations provided biological interpretations of groupings in terms of general stresses associated with winter wheat production. The relationships of international winter wheat test sites documented in this study should facilitate definition and understanding of regions of cultivar adaptation.