Growth and productivity of early and medium late maturing plum cultivars in the Belgrade area

Characteristics of growth and cropping (trunk cross-sectional area, yield tree^‑1, yield efficiency and biennial bearing index), as well as fruit weight were studied in 26 plum cultivars of early and medium late maturity time in the Belgrade area during an eight-year period (2012-2019). The cultivar ‘Čačanska Lepotica’ was used as a control for comparison. The period of study was divided to initial bearing (age of trees four and five years) and full bearing (age of trees from six to eleven years). Significant differences in yield among cultivars were found in both initial and full bearing periods. Average yield tree^‑1 in the period of initial bearing ranged from 1.0 kg in ‘Vengerka Yubileynaya’ to 8.2 kg in ‘Valerija’, and in the period of full bearing from 9.1 kg in ‘Venera’ to 28.1 kg in ‘Delikatnaya’. Compared with the control cultivar, significantly lower yield in the full bearing was obtained in 17 cultivars. Trunk cross-sectional area was significantly higher in five cultivars, and lower only in one cultivar (‘Valerija’). Cumulative yield efficiency varied from 0.36 kg cm^‑2 in ‘Venera’ to 1.96 kg cm^‑2 in ‘Valerija’. Biennial bearing index was the lowest (0.14-0.16) in cultivars ‘Čačanska Najbolja’ and ‘Čačanska Rana’, and the highest (0.63-0.66) in cultivars ‘Delikatnaya’ and ‘Green Gage’. Fruit weight ranged from 22.9 g in ‘Katinka’ to 67.7 g in ‘Reeves’. Compared with control, fruit weight was significantly higher in seven cultivars, and significantly lower also in seven cultivars. On the basis of high yield and large fruit size, cultivars ‘Valor’, ‘Reeves’, ‘Čačanska Najbolja’ and ‘Valerija’ are distinguished.