Regional and temporal variations in wheat yield in Western Australia and their implications in plant breeding

Abstract

The average annual wheat yields (bushels/acre) for each major wheat-producing shire in Western Australia were studied for a 40-year period from 1932 to 1971. Simple correlation coefficients provided an inadequate representation of the yield fluctuations over time and of regional differences. The data were then analysed by principal component analysis of the variance-covariance matrix. The order and magnitude of the vector coefficients provided clearly interpretable results distinguishing between-season from within-season components of variation and regional differences in respect of the magnitude of their relative contributions. Thus the method provided information that would otherwise be unavailable and the implication of these findings in the formulation of breeding programs is discussed.