Theoretical Framework for Crop Variety Trials

The ultimate purpose of crop variety trials is to identify superior cultivars for a given target environment. This chapter sets up the basic theoretical framework for crop variety trials. Heritability is the single most important concept in quantitative genetics with regard to variety trials. All measures taken in variety trials, from design, conduct, to statistical analysis, have the same purpose, that is, to improve the heritability of the variety trials. Another key concept regarding crop variety trials is that the heritability must be estimated under the genotype–location–year framework. In this framework, each test environment or trial is viewed as a location‐by‐year combination and is determined and defined by both the year and the location factors, which have different biological implications. The main task of the chapter is to examine the definition of heritability and its variants under various scenarios.