蜂访花与不同品种紫花苜蓿花部特征的相关性

紫花苜蓿Medicago sativa L.为严格的异花授粉植物，其授粉主要由蜂类进行。作者对10个不同品种紫花苜蓿的花萼直径、花冠长度、花朵密度、花蜜量及花蜜糖组成等花部特征与访花蜂数的关系进行了研究。结果表明，花部特征对访花蜂数的影响依次为： 单位面积花蜜量(r=0.93，P<0.01) >花朵密度(r=0.92，P<0.01) > 蔗糖含量(r=0.82，P<0.05) > 花冠长度(r=0.77，P<0.05) > 单花花蜜量(r=0.71，P<0.05)。对不同品种紫花苜蓿分别利用花部特征和访花蜂数进行聚类分析，结果显示小组划分虽然有所不同，但都能分为相同的两大组，即：阿尔冈津、陕北、L173、WL323和拉达克聚为一大组，而三得利、德福、赛特、Prime和德宝聚为另一大组。作者认为，花朵的大小是造成紫花苜蓿各品种间的蜜蜂拜访数量差异的首要因素，再次是花蜜量的多少，最后是花朵的颜色。

Interrelations of bee visitation and floral features in alfalfa

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 m~2, 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 m~2 (r=0.93,P<0.01) was in the first place, followed by the number of flowers per m~2 (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.