THE EFFECT OF POLLENIZER ON THE FRUIT SET OFPLUM CULTIVAR ČAČANSKA NAJBOLJA

In this paper, during a 4-year period (2003-2006) effects of sixpollenizers (President, Italian Prune, Stanley, Čačanska Rodna, Agen 707, andCalifornia Blue) on the degree of fruit set in the plum cultivar Čačanska Najboljawere examined. Besides the controlled pollination of this cultivar, open pollinationwas investigated. Functional pollen ability in pollenizer-cultivars was establishedby in vitro pollen germination. Degree of fruit set was determined comparing thenumber of fruit set (10 days after pollination, 21 days after pollination andnumber of harvested fruits) against the number of pollinated flowers. The resultsindicated that all pollenizer cultivars, studied in this paper, possessed satisfactoryin vitro pollen germination (30.1-67.4%). The number of fruit set determined 10days after pollination was very high and did not differ among pollenizers. Highlysignificant differences were found between the pollenizers in the number offruit set 21 days after pollination and significant ones in relation to the number ofharvested fruits. Compared to open pollination, higher number of fruit set 21 daysafter pollination and higher number of harvested fruits were obtained whencultivars Stanley (17.0%; 7.6%) and Italian Prune (14.6%; 6.9%) were used aspollenizers, therefore those cultivars are recommendable as good pollenizers forthe cultivar Čačanska Najbolja.