Heritability and Genetic Parameters Estimated for Fruits Size in F1

Abstract. Interspecific hybridization is a frequently used breeding method to create a wide genetic diversity useful to broaden selection base and creating new cultivars of apple. The aim of the present study was to determine the heritability of fruit size in F1 apple hybrids belonging to interspecific apple pollenization between different cultivars and wild species (rustic apple crabs) like Malus coronaria, M. floribunda, M. niedzwetzkyana, M. zumi, and M. prunifolia. A wide variability of fruits sizes has been identified, in all families being identified a broad fruit size variability (e.g. CV = 47.1 % in M. zumi × ‘Golden Delicious’, CV = 42.2 % in M. coronaria × ‘Jonathan ’ and ‘Rosu de Cluj’ × M. prunifolia). Between the five cyclic hybridizations, the mean of notes for fruit size was quite close, with limits ranging from 2.70, from hybridisation where the species M. floribunda and M. prunifolia participated as paternal testers, and 2.93, in the cyclic where specie M. niedzwetzkyana was hybridization as paternal tester (less than „3”, which express „small fruits”, by 1-9 scale). Even if the trait studied showed a strong genetic determinism (H2: 0.611-0.700), analysis of the heritability coefficients in narrow sense (h2 between 0.074 when M. prunifolia was used as paternal tester and 0.154 when M. floribunda was used as paternal tester) revealed that not additive effects played the most important role, but non-additive effects, of dominance and epistatic. Genetic gain and expecte