Modeling covariance structures for genetic and non‐genetic effects in cowpea multi‐environment trials

Abstract

In cowpea breeding, multi-environment trials are conducted to select lines with high yield. The occurrence of genetic and/or statistical imbalance is common in these experiments, in addition to the possibility of (co)variance between genetic and non-genetic effects. We explore the restricted maximum likelihood/best linear unbiased prediction features to select the model with the most appropriated covariance structure and compare the results with the traditional model (homogenous variances and no covariances). Then, 17 inbred lines and three cultivars were evaluated in six experiments during two crop years in the semiarid zone of Northeast Brazil. The trait evaluated was the 100-grain weight. We selected the best model considering the Akaike Information Criterion. The model with diagonal structure for the residual effects and heterogeneous compound symmetry for the genetic effects had the best fit. The predicted genetic gain of lines selected in this model was 1.18% higher compared to the traditional model. Modeling different (co)variance structures for genetic and non-genetic effects is an efficient approach in selecting superior genotypes in multi-environment trials in cowpea breeding. INTRODUCTIONThe World Health Organization (WHO, 2021) estimated that in 2020 about 149 million children under 5 were stunted, 45 million were very thin, and 38.9 million were overweight or obese. These problems are caused by malnutrition of nutrients, for example, protein, vitamins, or minerals, which occurs