Quantitative pollination requirements: A buzzworthy breeding objective for improving blueberry yield

Abstract

Blueberry yield and fruit quality are contingent on pollination. While beekeeping services are commonly employed to fulfill this requirement, adverse weather during the bloom period and the suboptimal efficacy of honey bee pollinators often result in pollen limitation and subsequent yield loss. Elucidating genotypic variability for quantitative pollination requirements can support breeding efforts to mitigate losses of yield and quality associated with pollen limitation. In this study, the effect of nine levels of pollen receipt (0, 5, 10, 20, 30, 50, 75, 100, 150 pollen tetrads) on the production of three southern highbush blueberry genotypes was examined. We studied the effect of genotype, treatment, and their interaction on seed number, berry size, weight, and ripening time. The quantitative pollination requirement for each genotype was determined via asymptotic regression, and variance components for fruit set were estimated using a mixed-effects model. Significant differences between genotypes and pollination treatments were observed for seed number, berry diameter, and weight (P < 0.01). Ripening time was also impacted by pollination treatment (P < 0.01), with higher pollen quantities resulting in shorter ripening times. The minimum pollination requirement to achieve maximum fruit set varied between genotypes, ranging between 25 and 60 pollen tetrads, although some instances of parthenocarpy and over-pollination were observed. These findings underscore the importance of genotypic variability for blueberry pollination outcomes and provide important evidence for breeding lowered pollination requirements.