GCA and SCA effects for ramification capacity of trees in F1 apple seedlings

Abstract

The number of branches per tree was analysed on F1 individuals originated in several crosses between apple cultivars with different architectural ideotypes: spur (Starkrimson, Golden spur), semispur (Liberty), weeping (Florina). The number of branches per tree in F1 hybrid apple, in their third year of vegetation, was different in six combinations, depending on the genotype of genitors, respectively on their architectural ideotype. There have been noticed significant differences among the tested cultivars used as genitors, the average of trait on hybrid combinations being comprised between 4.28 in Goldenspur × Liberty and 7.14 in Starkrimson × Florina. A small number of branches per seedling were registered in Starkrimson × Goldenspur combination (4.32), where the both genitors are spur ideotypes. The variability of analysed characters was high, with s% between 33.9 at Liberty × Florina and 56.8 at Starkrimson × Liberty. These values suggest that seedlings with very different number of branches are likely to be identified in each combination. The analysis of variance for GCA and SCA has emphasized the fact that, in the studied apple combinations, both effects of general and specific combining ability contributed to the phenotypic expression of the number of branches per tree. Goldenspur showed a negative value for GCA, thus this could produce descendants with low vigour and number of branches, if they are used as genitors in apple breeding. Based on the values of general combining ability (GCA) and specific combining ability (SCA) selection of genitors can be very efficient for desirable characters of growth in apple breeding.