Influence of rootstocks on size distribution and fruit quality of sweet cherry cultivars

In thecherry rootstock trials at Ullensvang, Norway the following quality prameters of sweet cherry cultivars: Van, Ulster and Burlat on seedling, Colt and Gisela 5 were evalua- ted: mean fruit weight, content of soluble solids, acidity, flesh firmness and percentage of fruit in individual size classes. The above quality parameters fluctuated markedly during the experi- mental summer period of 1998. Individual cultivars responded in various ways to the kind of rootstock. The kind of rootstock exerted a significant influence on the individual factors determining fruit quality. It significantly influenced fruit external features, i.e., their size and percentage of stone in total fruit weight. The largest fruit of cv. Van noticed on seedling rootstock, cv. Ulster - on Colt and cv. Burlat - on Gisela 5. However the largest stone-weight per total fruit-weight in all cultivars studied was in fruits from trees on Gisela 5. The fruits of all cultivars reacted with different firmness depending on the kind of rootstock. The firmest fruits on seedling and Gisela 5 rootstock stated at cv. Ulster. However the Colt fruits of cv. Van had the greatest firmness. Fruits of cv. Burlat characte- rized the lowest values of firmness compared to the rest of the culti- vars studied. The internal fruit features described by the amount of soluble solids, titratable acidity and pH of fruits juice was de- termined by the kind of rootstock.