Adaptation Patterns and Definition of Macro-environments for Selection and Recommendation of Common-wheat Genotypes in Italy

Eighteen common-wheat varieties grown for three seasons at 31 locations in Italy were used to study the relationships between cultivar adaptation patterns, climatic factors and morphophysiological traits of genotypes, as well as defining macro-environments for the selection and recommendation of genotypes in the region. The variances of both the genotype-location and genotype–season interactions were significant, the former being almost 80% greater than the latter. Some 10.4% of genotype-location interaction was accounted for by heterogeneity of genotype regressions on site mean, 38.0% by the first two axes of a principal components analysis and 32.0% by definition of four macro-environments. Occurrence of genotype-location interaction was related to the level of late frosts, winter cold, and late drought and heat stress at each location, and to heading date and tolerance of frost, Septoria blotch and lodging in each genotype. Following estimates of broad-sense heritability, breeding for specific adaptation may be envisaged for northern and central Italy on the one hand, and southern Italy on the other. Morphophysiological traits contributing to better performance in each of these macro-environments were indicated.