Effective pollination period in 'oblacinska' sour cherry clones

Abstract

To obtain high yields there should be high flower density and fruit set in sour cherry (Prunus cerasus L.) production. Furthermore, in order to ensure successful fertilization, there should be satisfactory stigma receptivity, rapid pollen tube growth along the style, as well as adequate ovule longevity. This manuscript presents the study of the effective pollination period (EPP) of four 'Oblacinska' sour cherry clones (II/2, III/9, XI/3 and XIII/1) that differs in pollen germination, fruit set and yields. In order to estimate EPP, pollination was conducted in six different stages of flower development: balloon stage, 2 d before anthesis (-2), at anthesis (0), and 2, 4, 6 and 8 d after anthesis (DAA). The initial (IFS) and final fruit set (FFS) were recorded under the field conditions. Alongside with this, the rate of pollen tubes growth in the style was observed with fluorescent microscopy. The experimental design was completely randomized, a two-factorial analysis of variance was carried out and individual testing was performed using LSD test (p lt = 0.05; p lt = 0.01). The experiment was set in triplicates. Regarding FFS, clones II/2 and III/9 showed the best results (p lt = 0.01) in 4 and 6 DAA. The number of pollen tubes in the style of the pistil decreased with subsequent terms of pollination, while its number in the ovule increased up to sixth day after pollination, followed by a decline. Clones II/2 and III/9 showed EPP which lasted from 6 to 8 d, while EPP found in clone XI/3, lasted only 2 d. It is concluded that only clone having long EPP should be used as parents for creating new sour cherry cultivars.