Persistence and Yield among Nondormant Alfalfas Selected for Grazing Tolerance

Abstract

Perennial, warm season grasses are the predominant pasture species in the Coastal Plain of the southern USA. These grasses have two major limitations: (i) an off-season (normally winter) when they have either limited or no production and (ii) low nutritional value during most of their main growing season. Using nondormant alfalfa (Medicago sativa L.) as supplemental grazing for grass pastures may overcome these limitations because it has a long growing season in areas with mild winters and also has high nutritional quality. However, alfalfa is generally not grazed due to poor stand persistence and grazing-tolerant cultivars are currently dormant types. Therefore, we used selection for survival after heavy grazing pressure with continuous stocking by beef cattle (Bos sp.) to develop two nondormant, grazing tolerant alfalfa germplasms. These were then tested for survival and forage yield in four experiments of 1 to 2 yr duration under heavy grazing pressure with continuous stocking by beef cattle at Tifton, GA. The selected, nondormant alfalfa germplasms persisted under heavy grazing pressure as well as the grazing tolerant, dormant cultivar, Alfagraze, but were better in respect to plant survival than other nondormant cultivar checks. All entries survived in control areas that were clipped at an early flowering stage. The yield of nondormant cultivars was better from late autumn through early spring than Alfagraze. Some winter damage occurred in 1 of the 4 yr for the nondormant germplasms and cultivars, which did not occur with Alfagraze.