Parthenocarpic fruit quality and production under pollinator-exclusion in southern highbush blueberry

Parthenocarpy is the phenomenon of seedless fruit formation without fertilization. This trait has drawn the attention of many fruit and vegetable breeders due to its ability to overcome insufficient pollination and secure yield. Blueberry (Vaccinium spp.) maintains one of the highest pollination requirements of all crops, demanding growers invest in seasonal pollination services. Nevertheless, blueberry continues to suffer from suboptimal fruit set due to ineffective honeybee pollination, and adverse weather conditions during the brief bloom period. Therefore, developing parthenocarpic blueberry cultivars could provide an economical and effective way to ensure fruit set with decreased dependency on seasonal pollination services. However, the effects of parthenocarpy on berry quality and production-related traits in blueberry is unknown. Therefore, this study aims to evaluate these characteristics in 13 southern highbush blueberry genotypes under two pollination conditions (open-pollination and pollinator-exclusion cages). Open-pollinated and non-pollinated fruits from the 13 blueberry genotypes were assessed for seededness, firmness, size, sugar-to-acid ratio, fruit set, yield, week of peak harvest, and the duration of the fruit development period. Non-pollinated parthenocarpic fruits took longer to develop and tended to be smaller, sweeter, and less firm than open-pollinated fruits. Despite these differences, most parthenocarpic fruits still met market standards. Genotypic differences were also observed, suggesting the opportunity to select for enhanced parthenocarpy in future populations. The results of this study demonstrate that facultative parthenocarpy can be exploited and incorporated into blueberry breeding programs to ensure proper yield in inadequate pollination conditions.