Location-by-Trait Two-Way Data Analysis

The main purpose of crop variety trials is to select superior genotypes. The extended purposes, which are the basis for effective genotype evaluation, are to understand the target environment (mega‐environment analysis) and to select test locations suitable for genotype evaluation. This chapter discusses a potentially very important aspect of variety trial data analysis – the analysis of location‐by‐trait data. The purpose of this analysis is to identify regions that are suitable for producing crop products with certain desired end‐use quality. The environment‐by‐trait (ET) biplot displays environmental correlations among traits, which can be very different from the genotypic correlations among traits. This implies that some problems that are difficult to solve genetically may be more easily solved environmentally. The chapter also shows how to implement the analysis.