Assessing the Representativeness and Repeatability of Test Locations for Genotype Evaluation

The success of a plant breeding program depends on many factors; one crucial factor is the selection of suitable breeding and testing locations. A test location must be discriminating so that genetic differences among genotypes can be easily observed, it must be representative of the target environments so that selected genotypes have the desired adaptation, and its representation of the target environment should also be repeatable so that genotypes selected in 1 yr will have superior performance in future years. Using the yield data of 2006 through 2010 Quebec Oat Registration and Recommendation Trials as an example, we presented a method to visualize the representativeness and repeatability of test locations based on a genotype main effect plus genotype x environment interaction (GGE) biplot. The repeatability of a test location could also be quantified by mean genetic correlations between years within the location. Based on representativeness and repeatability, four categories of test locations were classified and their usefulness in plant breeding discussed.