Utilization of pedigree information to estimate genetic parameters from large unbalanced data sets in apple

Abstract

 Genetic parameters (narrow-sense heritabilities and genetic correlations) were estimated for major agronomical traits in apple from large unbalanced data sets, with the help of wide-pedigree information. The software REML VCE (Groeneveld 1996) took into account the complex pedigree of the French apple-breeding population, thanks to the restricted maximum likelihood procedure combined with the construction of the entire relationship matrix between hybrids planted in the field and their ancestors. Narrow-sense heritability estimates ranged from 0.34 to 0.68 for traits exhibiting a normal distribution. Heritability values around 0.35–0.40 were obtained for fruit characteristics (size, texture, flavour, juice content, attractiveness, russeting). Higher values of heritability were obtained for vigour, assessed by the circumference of the trunk (0.51), and powdery mildew resistance (0.68). Additive genetic correlations between traits were also estimated, showing a very high relationship between fruit-quality traits. Vigour and powdery mildew resistance were slightly correlated with the other traits. Utilization of the ‘individual genetic model’ for the estimation of genetic parameters and breeding values in apple is discussed.