Evaluation of fruit bearing habit of apple, sweet cherry, walnut and strawberry cultivars in Bulgaria

One of the main aims in modern orchards is obtaining high quality fruits and regular cropping and managing the tree shape and fruit load with minimal pruning, by taking advantage of the natural trend of the cultivar and thereby reducing the cost of this manual operation. This motivated us to start at our Institute a bearing habit evaluation of cultivars from different fruit species, such as pome, stone, nut and small fruit groups. The fruit bearing habit as a part of fruit tree architecture was evaluated in apple orchards with 49 cultivars, including 22 resistant to scab on 'MM106' and 'M9' rootstocks. According to Lesspinasse classification, the cultivars have been divided in four fruiting types: type I 'Starkrimson', type II 'Reine des Reinettes', type III 'Golden Delicious' and type IV 'Granny Smith'. The apple cultivars of type I and II have the fruiting spur habit related to biennial bearing and type IV to regular ones. The fruiting type of 9 sweet cherry cultivars on 'Gisela 5' rootstock have been divided in two types - type I 'Sunburst' ('Regina', 'Kordia', 'Lapins', 'Katalin') and type II 'B. Burlat' ('Nalina', 'Summit', 'Hudson'). According to the type of bearing habit of 7 walnut cultivars grafted on Juglans regia L. seedlings, the lateral bearing cultivars 'Izvor 10', 'Fernor' and 'Lara' are very promising under our climatic conditions. The walnut trees have higher fruit and kernel weight on one-and two-year-old wood than on three-and four-year-old wood. The percentage of ripened strawberry fruits from first three pickings is more than 50% of the total crop from one-year-old plants in cultivars 'Thetis', 'Don', 'Seascape', 'Bogota', 'Selene', 'Selva', 'Idea', 'Linda' and it is higher than from two-year-old plants. The evaluation of the fruiting type helped us to improve and maintain a good balance between vegetative growth and productivity.