The Effect of Pollination Variant and Temperature on Reproductive Behaviour of Some Highbush Blueberry (Vaccinium coyimbosum L.) Cultivars

Pollination is a key factor in the production of highbush blueberry (Vaccinium corymbosum L.) to achieve a quantitatively and qualitatively satisfactory yield. Lower yields and small fruit without commercial value are correlated with poor pollination. This study was performed to investigate the flowering phenophase and pollen performance in vitro and in vivo of five cultivars (‘Duke’, ‘Reka’, ‘Bluecrop’, ‘Nui’ and ‘Ozarkblue’) that are commercially important in Serbia. Each cultivar was used as polleniser, while ‘Reka’, ‘Bluecrop’ and ‘Ozarkblue’ were also used as pollinated cultivars. Including the self- and open-pollination variants, a total of 18 combinations were investigated during the 3‑year study period. The studied blueberry cultivars flowered during the last third of April and the first half of May and, with the exception of ‘Ozarkblue’, had a satisfactory overlap in the flowering phenophase. There were genotype, year, and genotype × year interaction effects on pollen performance in vitro of the investigated blueberry cultivars. The pollination variant influenced pollen performance in vivo: The open-pollination variant was the most favourable in all tested cultivars, followed by the cross-pollination variant, with the exception of cultivar ‘Nui’ used as a polleniser, which showed worse results compared to the self-pollination variant. In addition, the pollinated cultivar impacted the pollen performance of pollenisers, while the impact of air temperature during the flowering phenophase can only be considered in the context of the responses for each male–female combination.