Influence of pollination mode on fruit set in plum (Prunus domestica)

Investigation of initial and final fruit set in the ‘Pozna Plava’ plum cultivar characterised by a low fruit set tendency was conducted in three pollination modes (cross-, self- and open pollination), over a two-year period (2010-2011). The cross-pollination was performed using the pollen of cultivars ‘Presenta’, ‘Hanita’ and ‘Čačanska Najbolja’. Pollen germination in vitro for the cultivars used in the cross-pollination was over 40%, whereas in ‘Pozna Plava’ it was less than 18%. In both years, the cross-pollination with ‘Presenta’ resulted in the highest initial (69.54 and 51.85%) and final fruit set (41.45 and 30.92%). In addition, high values of initial and final fruit set were also obtained with ‘Hanita’ and ‘Čačanska Najbolja’ as pollinizers. Self-pollination mode in both years resulted in somewhat lower initial (47.53 and 21.74%) and final fruit set (33.24 and 12.35%); and the lowest values were recorded in the open pollination mode (initial fruit set of 12.28 and 5.14%, final fruit set of 0.79 and 2.83%). The results revealed a clear impact of the pollination mode and air temperatures on the fruit set of plum cultivar ‘Pozna Plava’ during the first ten days from the beginning of full flowering.