Flower morphology and nectar quality traits in faba bean affect attraction to bees

Legumes provide nutritious floral resources for bees thus are commonly considered for use in schemes to enhance pollinators in agroecosystems. In particular, legume landraces are important elements in practices towards sustainable agriculture. Differences in flower morphology and nectar may affect the attraction of pollinators. The aim of the present study was to investigate possible differences in pollinator attraction between a Vicia faba L. landrace and a commercial variety and to indicate differences in floral characteristics and nectar quality traits which can be associated with bee visits. To assess this, floral morphological trait measurements and chemical analysis using high-resolution mass spectrometry-based non-targeted screening of the flower nectar were carried out and bee visits on faba bean flowers were recorded. Floral traits that contributed to the separation of the two accessions were 'intensity of streaks' and 'extent of anthocyanin colouration' on standard petal which were more pronounced in the landrace. All nectar traits examined contributed to the separation of the two V. faba accessions. Chemical substances such as amino acids and sugars which are important for bee nutrition are differentially increased in the landrace compared with the commercial variety. The landrace attracted more bee genera (Apis, Anthophora, Eucera) and bee visits compared with the commercial variety (only Eucera) supporting that the floral and nectar differences between the accessions of the same plant species are important to bees. The well-fitting interrelation of the landrace flowers and bee visits can have possible implications in agricultural practices such as crop breeding for pollinator friendly varieties through selecting floral traits, improvement of foraging resources for pollinators in agroecosystems and subsequently food production. Exploitation of the V. faba landrace in agroecological schemes to support conservation of flora and fauna genetic resources in situ should be considered also for the benefit of future food stability and security.