Pollination effects of the bumble bee and honey bee on white clover (Trifolium repens L.) seed production

SummaryThe effects of honey bee (Apis mellifera L.) and bumble bee (Bombus terrestris L.) pollination on white clover (Trifolium repens L.) seed yield, number of pods per head, number of seeds per pod and podding rate were evaluated in the Mediterranean region of Turkey. Experimental field plots were laid out in a randomized complete block design with three replicates in both spring and autumn harvest seasons. The four treatments consisted of plants caged with honey bees, plants caged with bumble bees, plants caged to exclude all pollinators, and open-pollinated plots. The highest seed yield was found in the caged honey bee treatment (46.2 kg/ha) followed by caged bumble bees (37.3 kg/ha), open-pollinated (25.7 kg/ha) and pollinator excluded (1.37 kg/ha) treatments in the spring harvest season. Seed yield was very low in the autumn (approximately 1/3 of spring) harvest season. It was significantly greater in the caged honey bee and bumble bee treatments than in the open-pollinated and pollinator excluded treatments in both harvest seasons. Similarly, the number of pods per head, the number of seeds per pod, and podding rate were higher in honey bee and bumble bee treatments than in the open-pollinated and pollinator excluded treatments. The results suggest that bumble bees can be used as an alternative pollinator to honey bees to enhance white clover seed production.