Effects of pollinizer density and apple tree position on pollination efficiency in cv. Gala

Pollen donor plants (pollinizers) availability and arrangement are considered fundamental to provide compatible pollen to main cultivar ensuring fruit production in apple orchards. Apple farmers manage pollination efficiency by setting the amount of pollinizer plants and the arrangement of pollinizer/main cv. tree within the orchard. Nowadays, an intermixed orchard design, consisting in mixing pollinizer with production trees, is usually adopted. Moreover, it is possible that pollen dispersal could involve pollinizers placed in surrounding orchards; therefore, this should be taken into account in orchard design. We sampled ‘Gala’ trees with different pollinizer densities combined with different positions within row in three orchards of North-West Italy assessing pollination efficiency. The density of pollinizer in main cv. tree surroundings affected positively pollination efficiency up to 30 m. In addition, only trees adjacent to pollinizers showed higher pollination level while trees differently positioned had lower and similar pollination efficiency. Our outcomes suggest intermixed orchard assures generally uniform pollination across the orchard and that farmers should design new orchards with a specific focus on pollinizer availability in the surroundings.