关键词: 自然蜂群, 访花, 紫花苜蓿, 花部特征, 花蜜, 蔗糖

Abstract: Alfalfa is a plant of strict allogamy, and its pollination relies mainly on bees. The author studied the relationship between the number of visiting bees and floral features, such as calyx diameter, coronary length, number of flowers per m², nectar amount, components of sugar and so on, in ten varieties of alfalfa. The results showed the significance order of floral features affecting the number of visiting bees was that the nectar amount per m² (r=0.93，P<0.01) was in the first place, followed by the number of flowers per m² (r=0.92，P<0.01), sucrose content of nectar sugar (r=0.82，P<0.05), coronary length (r=0.77，P<0.05) and nectar amount (r=0.71，P<0.05). The results of the cluster analysis showed that although the alfalfa varieties were classified into different sub-groups based on floral features in ten varieties of alfalfa or the number of visiting bees, but they could be classified into the same two higher groups: one consisted of Algonquin, Shanbei, L173, Wl323 and Ladak, and the other consisted of Sanditi, Defa, Sitel, Prime and Derby. It was concluded that flower size was the most important feature in affecting bee visitation, followed by nectar production and flower color.

Key words: Wild bees, visiting flower, alfalfa, floral feature, nectar, sucrose