Seed yields in canola (Brassica napus cv. Karoo) depend on the distance of plants from honeybee apiaries

This research examined the benefits of placing hives of honeybees (Apis mellifera L.) in canola (Brassica napus L.) at a density of approximately 1 hive/ha. We tested 3 main hypotheses. First, deploying honeybees increases the yield of seed. Second, that the benefits of honeybee pollination decline the further plants are from an apiary. Third, poorly pollinated plants should channel more resources into larger seeds, whereas plants benefiting from insect pollination should produce more but smaller seeds. The experiment confirmed all 3 hypotheses. Yields of seed increased by more than 20% or by 400 kg/ha, whereas the yield declined in plots located more than 200 m from the apiary. There are several explanations for the increased yield, including an enhanced production of fertile pods and, therefore, more seed, particularly small seed.