Improvement of the resistance to scab, rosy apple aphid and fire blight in a breeding programme of cider apple cultivars.

摘要

Based on previous evaluation of local cultivars, a programme for breeding cider apple (Malus domestica) cultivars was initiated in the SERIDA of Asturias (NW Spain) in 1989 with three major aims: to improve the durable resistance to diseases and pests of local cultivars, to obtain cultivars with no biennial bearing and to improve fruit quality. To achieve the first objective, Asturian cultivars with low susceptibility to scab were crossed with 'Florina', which is carrying the Vf gene of resistance to scab due to Venturia inaequalis and shows very low susceptibility to the fire blight caused by Erwinia amylovora and resistance to the rosy apple aphid (Dysaphis plantaginea). The first cross, performed in 1989, was 'Raxao' x 'Florina'. After greenhouse and nursery evaluation 34 hybrids resistant to scab (the presence of the Vf gene has been confirmed with molecular markers) and low susceptible to powdery mildew Podosphaera leucotricha were preselected. After evaluation of these 34 hybrids against the rosy apple aphid, fire blight, apple scab and powdery mildew as well as characterization of their productivity and quality, four hybrids were selected and are in registry at the present time. Numerous other crossings have been performed since then and are in different phases of evaluation and selection at the moment.