Determination of the self-compatibility and suitable pollenizers for the plum cultivar 'Nada'

The self-compatibility of the plum cultivar ‘Nada’ as well as suitability of five different pollenizers: ‘Čačanska Lepotica’, ‘Čačanska Rodna’, ‘Čačanska Najbolja’, ‘Stanley’ and ‘Mildora’ were studied over two years. The study included the evaluation of flowering phenology, pollen germination in vitro, pollen tubes growth in vivo and fruit set, in all crossing combinations. Pollen germination was determined on the medium with agar and 15% sucrose while fluorescence microscopy method was used for testing pollen growth in vivo. Regarding the flowering time, all pollenizers overlapped well with ‘Nada’. Tested pollenizers showed different pollen germination rates, ranging from 28.87 to 46.76%. An average number of pollen tubes at the base of the style and in the ovary was significantly higher with crossing combination: ‘Čačanska Rodna’, ‘Čačanska Lepotica’, ‘Mildora’ and ‘Stanley’, compared with ‘Čačanska Najbolja’. Selfed ‘Nada’ had very low fruit set (2.25%). The highest average fruit set in both years was obtained with ‘Čačanska Rodna’ (16.95%), ‘Mildora’ (14.70%) and ‘Čačanska Lepotica’ (13.50%) as pollinizers, while with ‘Stanley’ (9.45%) and ‘Čačanska Najbolja’ (8.65%) significantly lower fruit set was recorded. Based on these results, ‘Čacanska Rodna’ can be recommended as the best pollenizer for ‘Nada’. Satisfactory results were also obtained with ‘Čačanska Lepotica’ and ‘Mildora’ as pollinizers.