Mega-environment Analysis Based on Multiyear Data

Mega‐environment analysis has a long‐term impact on genotype evaluation and cultivar recommendation, and mega‐environment analysis must be based on multiyear data. This chapter demonstrates how to conduct mega‐environment analysis based on multilocation trial data from multiple years. Two strategies of mega‐environment analysis are demonstrated in the chapter: yearly GGL biplot analysis and multiyear GGE biplot analysis. Mega‐environment analysis will decide if a target environment consists of multiple mega‐environments, a single, simple mega‐environment, or a single, complex mega‐environment. Different breeding and testing strategies are needed for different types of target environments. Frequently asked questions regarding mega‐environment analysis were discussed. The questions include: which biplot form is best for mega‐environment delineation; and should mega‐environment analysis be conducted every year.