Effectiveness of Selection for Nectar Volume, Receptacle Diameter, and Seed Yield Characteristics in Alfalfa¹

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.

Foraging Range of Honey Bees,Apis mellifera, in Alfalfa Seed Production Fields

“…Along with foraging distance, the number of individual flowers visited and the spatial scale of the visits by a bee on any given foraging trip will dictate the degree of gene flow between RR and conventional alfalfa (Pedersen 1953; Teuber et al 1983; Cane 2002). Also, an alfalfa flower must be tripped in order to be successfully pollinated.…”

Grain Legumes

“…Recurrent selection in soybean with male-sterile, female-fertile mutants was reviewed by Lewers and Palmer (1997). These genetic differences in soybean should be amenable to plant breeding manipulation similar to what has been with alfalfa (Teuber et al 1983(Teuber et al , 1990.…”

Nectar in Hummingbird‐pollinated Neotropical Plants I: Patterns of Production and Variability in 12 Species

“…There is evidence that nectar production in some species is, to some degree, heritable (Pedersen 1953, Hawkins 1971, Teuber & Barnes 1979, Teuber et al 1983, Mitchell & Shaw 1993, Campbell 1996, Mitchell et al 1998, Golubov et al 1999). Other studies have not used genetic methods but have shown that individuals have consistent nectar phenotypes, sometimes across seasons (Pleasants 1983, Zimmerman & Pyke 1986, Hodges 1993.…”