Glandular hair densities in three perennial Medicago species

Abstract

Because a number of insect pests periodically reduce the yields and/or quality of alfalfa, control measures are often required to prevent or limit losses. Physical characteristics such as glandular hairs have been associated with resistance to alfalfa insect pests. This study was conducted to determine the occurrence and relationships of glandular hair density on three perennial Medicago species that can be crossed with alfalfa, M. sativa L. Glandular hairs were visually counted on the stem, leaflet margin, abaxial leaflet surface, leaf midrib, and petiole of M. glandulosa David, M. glutinosa Marshall Von Bieberstein, and M. prostrata Jacquin. Environmental and genotypic correlations were obtained to estimate the relationships between hair densities on different structures of each Medicago species. Erect glandular hairs were present on all the vegetative structures of the plants, but density and distribution varied within species. Mean hair density was relatively high and uniform on stems, petioles, leaflet margins, midribs, and abaxial leaflet surfaces of M. prostrata.