Evaluation of the effects of pollination on fruit size and quality of highbush blueberry

Pollination is an important factor affecting fruit development in highbush blueberry (Vaccinium corymbosum L.). Generally, cross-pollination produces many mature seeds in fruits, resulting in a relatively high fruit set, large fruits, and early maturation. However, the effects of cross-pollination on fruit quality vary depending on the seed parent and remain unclear. The aim of this study was to re-evaluate the pollination effects on fruit size and quality by comparing the fruits derived from a controlled pollination with single-genotype pollen and those resulting from an open pollination. Additionally, the effects of mature seed number on fruit size and quality were also evaluated by a correlation analysis. Fruit size and quality for ‘O’Neal’, ‘Blue Muffin’, ‘Sharpblue’, ‘Biloxi’, and ‘Sunshine Blue’ plants that had been controlled pollinated with ‘O’Neal’ pollen were compared with the corresponding data for open-pollinated samples. The mature seed number and percentage of mature seeds were higher for controlled pollination than for open pollination, with the exception of the controlled self-pollination of ‘O’Neal’ plants. Additionally, larger fruits were produced by controlled pollination than by open pollination for ‘Sharpblue’ and ‘Biloxi’. In contrast, the soluble solids content as well as the fructose and glucose concentrations did not differ between controlled cross-pollination and open pollination. Additionally, the effects of controlled cross-pollination on the acidity and anthocyanin concentration varied in a seed parent- and treatment-dependent manner. A significant correlation was detected between mature seed number and fruit weight; however, fruit quality parameters were not clearly correlated with mature seed number for most cultivars. Our re-evaluation of the relationship between mature seed number and fruit quality implies that controlled cross-pollination may not significantly improve fruit quality even though it significantly increases the number of mature seeds.