No abstract

California produces more than 30% of the US alfalfa (Medicago sativa L.) seed crop. The majority of this seed is produced using honey bees (Apis mellifera) for pollination. Strength of reward, i.e. quantity and quality of nectar, is a primary factor in pollinator foraging activity. Positive correlations occur between nectar production and honey bee visitation, and honey bee visitation and seed production. Objectives of this investigation were to determine the effectiveness of phenotypic recurrent selection for increased nectar volume production and receptacle diameter and to determine the relationships among receptacle diameter, seeds/pod, seed production, and nectar volume in alfalfa. Populations of ‘CUF‐101,’ ‘Team,’ and ‘Vernal’ origin were developed by two cycles of phenotypic recurrent selection under either greenhouse conditions for nectar volume and receptacle diameter or field conditions for seeds/pod and seed production. Selection for either nectar volume or receptacle diameter resulted in a significant linear response in receptacle diameter. Nectar volume responded in a linear fashion to selection for nectar volume but did not respond when selection was for receptacle diameter. Selection for seeds/pod produced a significant linear response in nectar volume. Selection for seed production had no effect on nectar volume or receptacle diameter. Initial selection for receptacle diameter followed by nectar extraction should be an effective method of increasing nectar volume production.