The pollination of onion (Allium cepa L.) to produce hybrid seed.
Blocks of onion plants were either caged with honeybee colonies or left uncaged. Although the uncaged plants produced fewer umbels, the weight of seed per umbel suggested that pollination was adequate. Seed production by the male-sterile plants did not decrease when the number of male-sterile rows between male-fertile rows was increased from 4 to 8.In general, bees collecting nectar only (as well as bees collecting nectar and pollen) preferred male-fertile to male-sterile plants, but moved between the two types sufficiently to effect adequate pollination.Observations of bumble bees at a cultivar selection trial showed that the cultivars differed in their attractiveness: the numbers of foraging bees on a cultivar ranged from 0 to 49 for a 1.2-m row containing 8 plants.J.M. Gedye