Screening and Characterizing Alfalfa for Persistence under Mowing and Continuous Grazing1

Alfalfa (Medicago sativa L.) is a high quality forage species that does not persist well under frequent, intense defoliation such as continuous grazing. Experiments were performed to screen alfalfa cultivars for persistence under mowing and continuous grazing and to identify plant characters that may be associted with persistence. Twenty‐two alfalfa cultivars were grazed continuously for 100 days in each of 3 years to a height of 3 to 5 cm, and mowed infrequently in a nearby area during the same period. Cultivars did not differ significantly for persistence under mowing, but did under grazing. Persistence of cultivars under mowing and under grazing was not correlated. Persistent and nonpersistent cuitivars were subsequently examined for differences in topgrowth and carbohydrate utilization. Topgrowth and total nonstructural carbohydrates in the taproots were less for persistent cultivars than nonpersistent cultivars. Persistent cultivars appeared to depend less on taproot carbohydrates for initial topgrowth than nonpersistent cultivars. The prospects for selecting alfalfa for persistence under grazing are promising, but such selection could possibly lead to less productive alfalfa lines unless care is taken to insure productivity as well as persistence.