Total Available Carbohydrates in Roots of Sainfoin ( Onobrychis viciaefolia Scop.) and Alfalfa ( Medicago sativa L.) when Grown Under Several Management Regimes 1

Total available carbohydrate (TAC) in roots of alfalfa ( Medicogo sotiva L.) and sainfoin ( Onobrychis viciaefolia Scop.) was measured throughout the growing season when plants were left uncut or cut two, three, and four times. TAC in roots of uncut alfalfa declined with the advent of spring growth, increased to a peak at 1/10 bloom, declined again with new growth, and then increased to a stable level in late summer and fall. In contrast, TAC in roots of uncut sainfoin decreased until flowering and then increased until seed had matured. New basal shoot growth did not occur during this period. At seed maturity, new basal shoot growth was accompanied by a slight decrease in root TAC followed by an increase and stabilization of TACle vel in early fall. Whenc cut two, three, or four times, TACin roots of alfalfa followed a typical pattern of accumulation and utilization. TAC in roots of sainfoin showed less cyclic fluctuation with cutting and remained at low levels until late summer and early fall. It was hypothesized that following the use of TAC reserves in early spring, growth of sainfoin depends primarily upon carbohydrates synthesized in existing leaf area.