Alfalfa leaf protein and stem cell wall polysaccharide yields under hay and biomass management systems

Alfalfa (Medicago sativa L.) has been proposed as a biofuel feedstock in which the stems would be processed to produce ethanol and the leaves sold separately as a livestock feed. Our objectives were to evaluate the effects of management strategy on leaf crude protein (CP), and stem carbohydrate concentrations and yields of alfalfa germplasms differing in genetic background. Two hay-type and two biomass-type alfalfas were established at 450 plants m(-2) and harvested at early bud (hay, management system) and at 180 plants m(-2) and harvested at green pod (biomass management system) in three environments. The biomass-type alfalfas under the biomass management had lower leaf CP, higher stem cell wall polysaccharide, and higher stem lignin concentrations, comparable leaf CP yield, and 37% greater stem cell wall polysaccharide yields compared to the hay-type alfalfas under the hay management treatment. The impact of altered stem cell Wall composition and increased stem dry matter yield of a biomass-type alfalfa under the,biomass system compared to a hay-type alfalfa under the hay system increased the theoretical potential ethanol yield by 99%.