Seminatural habitats and their proximity to the crop enhances canola (Brassica napus) pollination and reproductive parameters in Argentina

Abstract

The diversity and abundance of pollinators increase in cultivated areas in proximity to natural and seminatural habitats (pastures, forests, tree lines, etc.). Managing ecosystem services, such as insect pollination, is essential to increase crop yields. Although insect pollination is linked to better yields in many crops, pollinators are usually not considered as an input to be managed in crop production. In this study, we evaluate, for the first time, the influence of pollinators on the reproductive parameters of three canola (Brassica napus L.) stands placed at different distances from seminatural habitats in central Argentina. Insect visits to inflorescences with exposed and nonexposed flowers (covered with voile bags) were compared in plants growing in proximity (<50 m) and distant from (>50 m) seminatural habitats. Observations of flower visitations by the insects were recorded during the flowering period. The most frequent pollinator was Apis mellifera, although 12 additional pollinator morpho-species were registered. Seven of them were observed in canola flowers for the first time. Pollinators increased the amount of pollen deposited on stigmas and all measured reproductive parameters (fruit set, seeds per pod, seed mass). Seed production per infructescence increased with proximity to seminatural habitats and with pollinators by 34 and 35%, respectively. Therefore, the pollination ecosystem service is a relevant input for canola production in central Argentina. It will be important to develop policies that encourage diversified farming systems securing the protection of natural flora and pollinators.