UTILIZATION OF PEDIGREE INFORMATION TO ESTIMATE GENETIC-PARAMETERS FROM LARGE UNBALANCED DATA SETS IN APPLE

yGenetic parameters (narrow-sense heritabilities and genetic correlati ons) were estimated for major agronomical traits in apple from large u nbalanced data sets, with the help of wide-pedigree information. The s oftware REML VCE (Groeneveld 1996) took into account the complex pedig ree of the French apple-breeding population, thanks to the restricted maximum likelihood procedure combined with the construction of the ent ire 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 ar ound 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 o f the trunk (0.51), and powdery mildew resistance (0.68). Additive gen etic correlations between traits were also estimated. showing a very h igh relationship between fruit-quality traits. Vigour and powdery mild ew resistance were slightly correlated with the other traits. Utilizat ion of the 'individual genetic model' for the estimation of genetic pa rameters and breeding values in apple is discussed.