Studies on Estimation of Phenotypic Stability: Tests of Significance for Nonparametric Measures of Phenotypic Stability

Abstract

Parametric methods for estimating genotype-environment interactions and phenotypic stability (stability of genotypes over environments) are widely used in plant and animal breeding and production. Several nonparametric methods proposed by Huhn (1979, EDP in Medicine and Biology 10, 112-117) are based on the ranks of genotypes in each environment and use the idea of homeostasis as a measure of stability. In this study the statistical properties and tests of significance for two of these nonparametric measures of phenotypic stability (mean of the absolute rank differences of a genotype over the environments and variance among the ranks over the environments) are investigated. The purpose of this study is to develop approximate but easily applied statistical tests based on the normal distribution. Finally, application of the theoretical results is demonstrated using data on 20 genotypes (varieties) of winter wheat in 10 environments (locations) from the official German registration trials.