FORAGE QUALITY VARIATION AMONG MAIZE INBREDS - IN-VITRO DIGESTIBILITYAND CELL-WALL COMPONENTS

Forage maize (Zea mays L.) hybrids with improved feeding value might b e produced if breeders had better information about inbred variation i n maize for stover quality. This study was conducted to determine vari ation for in vitro digestible dry matter (IVDDM) and cell-wall compone nt concentrations among elite maize inbred lines and to determine the relationship between IVDDM and cell-wall components. Leaf blades and e longated basal stem internodes of 45 maize inbred lines grown near Ame s, IA, were sampled at an early harvest near silking, and stem interno des were sampled again at a late harvest near physiological maturity. Significant variation existed among the inbreds for IVDDM and cell-wal l components. Variation was greatest in late-harvest stems and least i n leaf blades. The IVDDM ranged from 262 to 650 g kg(-1) dry matter (D M) in late-harvest stems, from 465 to 727 g kg(-1) DM in early-harvest stems, and from 580 to 676 g kg(-1) DM in leaf blades. Stem IVDDM was most closely associated with stem neutral detergent fiber concentrati on both at the early harvest (r = -0.74) and at the late harvest (r = -0.82), whereas leaf IVDDM was most closely associated with leaf ligni n concentration (r = -0.61). Early-harvest stem IVDDM was not closely associated with leaf IVDDM (r = 0.31) or late-harvest stem IVDDM (r = 0.40). Hence, effective selection for improved IVDDM of maize stover m ay require total stover sampling near physiological maturity.