Fertilization biology of 'Reka' highbush blueberry

The paper presents results of the three-year study of fertilization biology of 'Reka' highbush blueberry (Vaccinium corymbosum L.) under the cross-, open and self-pollination variants. Cross-pollination was performed using the pollen of 'Bluecrop', 'Duke', 'Nui' and 'Ozarkblue'. Pollen tube growth in vivo was monitored using fluorescent microscopy method. The folowing parameters were observed: the average number of pollen tubes in the upper part and base of the style, number of ovary locules with the penetration of pollen tubes, and polen tubes' growth dynamics through certain pistil parts. The highest number of pollen tubes in the upper part and base of the style, as well as the fastest penetration into the ovary locules were found in the open pollination variant. Significant decrease of pollen tubes number from the upper third to the base of the style has been recorded in all pollination variants, whereas in the self-pollination variant it was to the greatest extent. The results also indicated that pollen tube growth dynamics in the progamic phase of fertilization was significantly influenced by pollenizer genotype and environmental factors, temperature in particular. On the second day after pollination, pollen tubes penetrated the ovary locules in all pollination variants, implying that favourable period for fertilization in this cultivar was one to two days after flower opening. In self- and cross-pollination variants, dynamics of pollen tubes growth was similar, indicating that cultivar 'Reka', commonly grown in multi-varietal, could also be grown in mono-varietal plantations (without pollenizers).