Artvin Coruh University Journal of Forestry Faculty

Abstract

In forest tree breeding studies, genetic parameters are estimated for breeding programs with long-term genetic tests. Since the estimations of these parameters will affect the breeding program, the selection of the linear mixed model to be used for the estimation is of great importance. In linear mixed models used for the estimation of these parameters, the estimation is usually obtained by using the residual or restricted maximum likelihood (REML) methods. In order to compare the models with different fixed effects with the information criteria based on likelihood, it is suggested that the models should be estimated using maximum likelihood. In forest tree breeding studies, different models should be tried in linear mixed model selection and the most useful model that increases model fit should be selected. It is generally recommended to use the Akaike (AIC) information criterion to compare the fit of models in forest tree breeding studies. In this study, it is aimed to reveal the necessity and importance of linear mixed model selection. For this purpose, the models were compared by using the twelfth year diameter at breast height data of the trees in the red pine progeny trial field established with 168 open pollinated families (half-sib) in Muğla-Marmaris. In the analysis of this data set, a total of 32 different models were tested, which include traditional (simple), spatial component, and assume that the residual is an independent or 1st order 2-dimensional separable autoregressive correlation error structure. The AIC value of the traditional model (Model-1=5594.1) was found to be higher than the models with the spatial component and the residual autoregressive correlation structure (Model-20=5447).