Fuctionality of embryo sac and fruit sets in plum cultivar ‘Čačanska Rana’

Abstract

‘Čačanska Rana’ is a dessert plum cultivar of excellent quality that can reach good price in the market. It is self-incompatible cultivar which has irregular yielding with year-to-year variation. For achieving good fruit set and high yields, it is necessary to conduct successful pollination and fertilization where many cyto-embryological processes must take place at the right time. In this study, functionality of embryo sac − their viability and fruit set, were used to evaluate fruit set in open pollination and emasculated unpollinated flowers as control (onset of full bloom on the third, sixth, tenth, fourteenth and twenty-first day after onset of full bloom) in ‘Čačanska Rana’ during the two years period (2015/2017). Considering the results of functionality of embryo sacs (8-, 5- and 4- nucleate stages), their viability was slightly longer in 2015 compared to 2017. In both years, fast degeneration of one out of two synergids and presence of 3- nucleate stage (with normal egg cell) up to fourteenth days of full flowering were observed. The embryo development recorded after fourteenth day after onset of full bloom. On the other hand, fruit set (24%) was higher in 2015, compared to fruit set (5.3%) in 2017. These results indicated that functionality of embryo sac as one of the factors that may be responsible for irregular yield of ‘Čačanska Rana’.