COMPARISONS OF SPECIES AND HYBRID ROOTSTOCKS FOR EUROPEAN PLUM CULTIVARS

Growth and yield of 'Victoria' plums, raised on several dwarfing or se mi-dwarfing rootstocks, or on their own roots, were compared in trials in Great Britain and the Netherlands. Victoria plums grown on the Fre nch hybrid rootstock Ferlenain (P.2038) formed dwarf trees of smaller stature, but yields similar to, or higher than, those on the dwarfing rootstock Pixy. Fruit size was in general much larger from trees on 'F erlenain'. Cv. Czar initially grew more vigorously on 'Ferlenain' than on 'Pixy', but after eight years in the orchard 'Czar'/'Ferlenain' we re the smallest trees. In many years fruit from the trees on 'Ferlenai n' were larger than those from trees on 'Pixy'. Ferciana, another Fren ch rootstock, formed larger trees similar in size to those on 'St. Jul ien A', but with better fruit size. 'Victoria' grown on its own roots from micropropagules formed much larger trees than 'Victoria' on 'Ferc iana', but with similar yields and poorer fruit size. There was no evi dence of increased shoot growth and/or delayed cropping due to scion r ejuvenation following micropropagation.