NONLINEAR GENOTYPIC RESPONSE TO MACROENVIRONMENT AND MICROENVIRONMENT

Environmental variation can be due to macro-and microenvironments. Whe reas macroenvironments, such as climate, density, and nutritional leve ls, are distinguishable, microenvironments including external random e rrors or internal ''accidents'' of an organism cannot be well specifie d. A quantitative genetic model is proposed to estimate the genetic co ntrol of response of genotypes to these two kinds of environments. The model extends Gimelfarb's additive-multiplicative model for genotype x environment interaction by considering both macro- and microenvironm ental variation and the mechanistic basis of genotypic response to a p articular macroenvironmental factor. It is further extended to estimat e genetic correlations between quantitative traits under the additive- multiplicative model. An example from a forest tree was used to illust rate the application and power of the new model. In many aspects, the model displays remarkable advantages over the traditional analysis of variance used to study genotype x environment interaction.