Contribution of pollinators to delivering fruit quality in commercial sweet cherry orchards

Background
Pollinators provide an essential ecosystem service to many crops, including sweet cherry (Prunus avium), which can be quantified in terms of fruit number and/or quality. Most studies in sweet cherry have explored the extent to which fruit set relies on pollinators but have neglected pollinators' contribution to fruit quality. We investigated the impact of pollinators on fruit set (2018–2019) and fruit quality (2017–2019). In 10 commercial sweet cherry orchards under polytunnels, we conducted insect-exclusion experiments comparing insect-excluded blossoms (mesh-bagged blossoms) to blossoms exposed to floral visitors (open blossoms). We then investigated relationships between fruit set and fruit quality.

Results
Pollinators were key to underpinning commercial fruit set (15.4% fruit set from open blossoms compared to 1.1% with bagged blossoms), equivalent to a contribution of 92.8%. Pollinators were also essential to achieving higher cherry fruit quality. With open blossoms, fresh mass, width, dry matter, and flesh/pit ratio of cherries increased by 19.8%, 7.9%, 19.8%, and 10.5%, respectively, compared to cherries from bagged blossoms. In contrast, firmness was similar between both pollination treatments. We did not find a significant relationship between fruit set and quality, suggesting trees did not carry an excessive fruit burden.

Conclusion
Our results highlight the importance of pollinators, not only for underpinning commercial yields in terms of fruit set, but also for higher fruit quality. We recommend growers adopt effective pollinator management practices to help underpin commercially viable yields consisting of fruit with a higher marketable potential.