Environmental stratification for wheat in South America

In South America, wheat is cultivated in an extensive territorial area, which includes very heterogeneous cultivation environments. Grain yield ends up influenced by the interaction of genotypes (G) with environments (A). The aim of the present study was to investigate the possibility of stratification of this important cultivated region, in order to minimize the negative effects of the GA interaction. Fifty wheat lines were evaluated for grain yield character, in eight locations in South America, during spring/summer and summer/autumn 2011. Data were provided by CIMMYT and submitted to joint analysis of variance by means of linear model with random effects. The genetic correlation between pairs of sites was estimated by obtaining a matrix of Euclidean distances, on which cluster analysis was applied by the Ward method. Three environmental strata were identified, formed by the grouping of Quilamapu-CL, Santa Catalina-EC, Marcos Juarez-AR (sub-region 1), Molle-Molle-BO and San Pedro-BO (sub-region 2), and Criadero- AR, INIAF-BO, El Montero-PE (sub-region 3). The evaluation of wheat lines in INIAF and El Montero should be prioritized, given the greater power of discrimination of genotypes in these locations.