Effect of bee pollination on yield and yield components of field bean (Vicia faba L.)

The effect of bees on the yield of field bean (Vicia faba L.) was studied in cage experiments in southern Finland during two successive years. Comparisons were made between field cages with and without honeybees and open-pollinated uncaged controls. Effect of shading was also considered. The yield in open plots, which were freely visited by pollinators, was considerably greater than in plots from which the insects were excluded. Freely visited plants and plants caged with bees produced about twice as many seeds as plants caged without bees, and the number of seeds per pod was also higher. The plants were tallest in cages without bees. In open plots, 44 % of the bee visitors were honeybees, 56 % being bumblebees. The higher number of seeds obtained with honeybee pollination indicates that honeybees are able to pollinate the field bean flowers in the conditions prevalent in Finland. – It is concluded that there is little value in introducing bee colonies in small field bean areas and places where bumblebees are fairly abundant. Honeybees may improve the yield in larger fields, where natural pollinators are often scarce.