Influence of Cultivar and Rootstock on Phenological Characteristics of Plum

The influence of three clonal rootstocks (‘Pixyʼ, ‘Fereleyʼ and ‘St. Julien Aʼ) together with seedlings of Myrobalan (control) on the phenological characteristics (flowering and harvest date) of the plum cultivars ‘Čačanska Ranaʼ, ‘Čačanska Lepoticaʼ and ‘Čačanska Najboljaʼ was studied in the Belgrade region (Serbia) over three years. The meteorological conditions during the study years were a source of variability in the results related to flowering time. The earliest start, full and end of flowering were recorded in the second experimental year, while the latest flowering phase occurred in the first. The rootstocks had no effect on flowering time, while the harvest date was 3–5 days later for the clonal rootstocks than for the seedling rootstock. Among the cultivars, the earliest harvest date was for the cultivar ‘Čačanska Ranaʼ, which also required the fewest days from full bloom to harvest. The study presents the correlation matrix between the investigated indicators of phenological characteristics and air temperatures for the studied combinations of plum cultivars and rootstocks, which shows that the phenological characteristics (flowering and harvest date) are directly influenced by the meteorological conditions in the investigated years.