Orchard performance of two plum cultivars on some clonal rootstocks

A plum rootstock trial with Stanley and Cacanska najbolja cvs. was established in spring 1992. The following rootstocks were assessed: MY-BO-1, Myrobalan SE 4043 (both Prunus cerasifera), MY-KL-A (P. cerasifera × P. cerasifera var. atropurpurea), Marunke SE 4034 (Ackerman), St. Julien A, Brompton, GF 655/2, GF 1869, GF 1380, GF 43, Damascena SE 4045, Pixy and Myrobalan seedling. Yields, trunk cross-section area, number of suckers and mean fruit weights were evaluated in the orchard in 1993-2003. There were statistically significant differences in trunk cross-section area, yield and yield efficiency between the tested rootstocks. Trees of Stanley were the most vigorous on MY-KL-A, followed by GF 43, GF 1380 and Myrobalan seedling. The weakest growth was recorded on trees grafted on Pixy, then on GF 655/2 and MY-BO-1. With Cacanska najbolja the growth was the strongest on GF 43, followed by Myrobalan seedling, MY-KL-A and Myrobalan SE 4043. The most compact trees were on Pixy and then on GF 655/2 and Marunke SE 4034. The total accumulated yield per tree was the highest with Stanley on MY-KL-A, followed by Brompton and St. Julien A. The cultivar Cacanska najbolja was most productive on Myrobalan SE 4043 and also on St. Julien A. The yield efficiency with both cultivars was the highest on GF 655/2, and the lowest one on GF 1380 (Stanley) or on Myrobalan seedling (Cacanska najbolja). No statistically significant differences between the tested rootstocks were found in fruit size. Suckers were the most prolific on GF 1869, followed by GF 655/2 and Marunke SE 4034. Based on the hitherto experience, the best rootstocks for Stanley seem to be MY-KL-A and MY-BO-1 and for Cacanska najbolja Myrobalan SE 4043 and St. Julien A.