Plant Compositional Changes Resulting from Two Cycles of Directional Selection for Nutritive Value in Alfalfa¹

Abstract

Progeny from three‐clone combinations of alfalfa ( Medicago sativa L.) selected for high or low 6‐hour in vitro matter disappearance (6H‐DMD) had significantly different neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) concentrations. The only significant change in cell wall composition was lower‐calculated hemicellulose (NDF‐ADF) of the cell walls of progeny from clones with high 6H‐DMD. Leaves of two‐clone combinations with high or low 6H‐DMD had similar NDF concentrations, but stems differed significantly in NDF. Histological studies of the stems revealed greater number of xylem cells in progeny with high NDF and low 6H‐DMD.