Cell‐Wall Components in Divergent Germplasms of Four Perennial Forage Grass Species

Abstract

Neutral‐detergent fiber (NDF) is an estimate of total cell‐wall (CW) components, which limit digestibility in forages. This study was conducted to determine whether concentration differences exist for NDF and CW components in four perennial grasses and to what extent these can account for reported variation in digestibility. ‘Napier’ and ‘Orion’ orchardgrass (Dactylis glomerata L.), ‘Barton’ and ‘Rebound’ smooth bromegrass (Bromus inermis Leyss.), germplasm of reed canarygrass (Phalaris arundinacea L.) selected for high or low specific leaf weight, and germplasm of tall fescue (Festuca arun‐dinacea Schreb.) selected for high or low rate of leaf‐area expansion were seeded in mid‐August on a Webster silty clay loam (fine‐loamy, mixed, mesic Typic Haplaquoll). At several spring harvests in 2 yr, total herbage and plant parts were assayed for NDF and CW components. Despite large differences in tiller size, NDF concentration of herbage and plant parts did not vary consistently between germplasms within reed canarygrass or tall fescue. Thus, selecting for fast growth rate and large tillers did not affect concentrations of NDF or CW components. In orchardgrass, NDF concentration was 3% greater and CW‐lignin concentration was 24% greater in Napier than in Orion herbage. In smooth bromegrass, NDF concentration was 5% greater in herbage and stems of Barton than of Rebound; CW‐lignin concentration was 5% greater in stems of Barton than of Rebound. In orchardgrass, cultivar variation for herbage digestibility was an inverse function of CW‐lignin concentration; in smooth bromegrass, variation in NDF and CW‐lignin concentrations had equal effect.