Pollination as a key management tool in crop production: Kiwifruit orchards as a study case

Abstract Despite the key role of pollination in the production of many crops, this is still one of the least understood factors in the orchard context. Pollen limitation, and impacts on crop production, is influenced by several potentially interacting factors such as crop or crop variety degree of dependence on cross pollination and on pollinators, diversity and abundance of the pollinator communities, landscape context and climate conditions. Understanding the pollination needs within an orchard is key to determine if the pollination is optimal or if it needs improvement. In some crops, such as kiwifruit, artificial pollination may be required where and when natural pollination cannot be improved or there is lack of pollen. In this study we quantified improvements to productivity resulting from artificial pollination and the efficiency of the technique for kiwifruit production and monetary gain on seven orchards distributed over the production range of this crop in Portugal. For that, we quantified orchard yield under 1) current natural pollination services, including pollination provided by wind and naturally occurring pollinator communities, 2) after artificial pollination and 3) under optimal pollination services. We characterized fruit production and key fruit traits such as fruit weight, size and caliber, and used production values, fruit caliber and respective market values to calculate the economic impact of pollination improvement. Results showed that pollen supply improved kiwifruit production in most orchards, either by changes in fruit set, fruit weight or both, and/or changes in fruit distribution by caliber and category. However, artificial pollination was not always efficient and/or needed. Contrarily to the expected, the artificial pollination treatment did not increase fruit weight but, in some orchards, it resulted in higher proportion of high-quality market fruits and/or lower proportion of unmarketable fruits. The changes in fruit traits translated into a tendency towards a small to moderate increase in monetary gain in four out of the seven orchards. This study reinforces the need to understand the current status of pollination services within the orchard context and to look at artificial pollination as a management tool in kiwifruit production. We conclude that pollination services in the study region might be sufficient to attain profitable yields; however, artificial pollination could be a useful tool under unpredictable pollination scenarios, but reviews of the efficiency of the methodologies used in this region are still necessary.