Influence of Rootstock on Plum Flowering Intensity in Different Growing Regions

The aim of the investigation is to evaluate the influence of different rootstocks on the flowering intensity of two plum cultivars: a hybrid `Kubanskaya Kometa` and European plum ‘Victoria’ in diverse locations. Sixteen well known European rootstocks were used, of which eight were clonal (St. Julien A, Brompton, Ackermann, Pixy, GF8/1, G5/22, GF655/2, Hamyra) and eight were seedlings (St. Julien INRA2, St. Julien d Orleans, St. Julien Noir, Brompton, Wangenheims Zwetche, St. Julien Wädenswil, Myrobalan, P. cerasifera var. divaricata). The evaluation was conducted in experimental orchards which were established in spring 2001 in Latvia, Estonia and Belarus. Trees were planted at a spacing of 5 × 3 m in four replications, three trees per plot. The obtained data from the years 2008-2012 are presented. The flowering intensity of plum trees depended on the cultivar rootstock combination. The influence of rootstock on flowering intensity differed between the years and growing region, and was closely correlates with meteorological conditions during the wintering period. Cv. ‘Kometa Kubanskaya’ had the highest blooming intensity in Pûre on rootstocks GF 655/2 and Wangenheims Zwetche; in Brest on Brompton seedlings, Julien d’ Orleans G5/22 and Ackermann; and in Polli on GF 8/1 and Brompton seedlings. ‘Victoria’ plum trees had the highest intensity of flowering on rootstocks Pixy and Wangenheims Zwetche in Pūre; on St. Julien INRA 2 and Ackermann in Brest; and on GF 655/2 and Ackermann in Polli.