The Climatic Sensitivity of ‘Green Revolution’ Wheat Culture in Sonora, Mexico

Abstract

A statistical model was developed to assess the effects of interannual climatic variability on wheat yields in Sonora, Mexico, where the high-yielding variety (HYV) agricultural ‘package’ was first developed. The approach taken was necessary because of the lack of suitable ‘dynamic’ formulations. The climatic terms in the model—transformed monthly mean temperature and precipitation values—explain almost 37% of the variance in the yield time-series, after allowing for the simultaneously generated base and trend values. This figure is somewhat less than that in similar formulations for North American wheat, where the climatic and yield data may be more reliable.The yields are most sensitive to preplanting moisture input, when the irrigation system is being recharged, and to March temperature, when fertilization can be reduced by heat. The yield response to these two variables was found to increase significantly as more HYV agriculture is adopted. Increases are over twofold for the precipitation term, and nearly threefold for the temperature variable.A variety of arguments suggests that the results truly indicate an increased climatic sensitivity in the yieldresponse, although the formulation is incapable of discriminating between sensitivities that are purely ‘genetic’, and those associated with the cultural practices which the genetic change allows to be established. When impacts upon the consuming population are considered, the distinction between the two becomes somewhat less important.