Clonal Selection for Lignin and Etherified Ferulates in Three Perennial Grasses

Decreased lignin concentration or decreased ferulate cross-linking between arabinoxylans and lignin are two mechanisms to increase cell-wall digestibility in plants. The objectives of this study were (i) to determine the consistency and clonal repeatability of lignin and etherified ferulates across multiple harvest dates and years, (ii) to determine if the genetic correlation between lignin and etherified ferulates can be altered by intensive selection, and (iii) to determine the effects of lignin and ferulates on digestibility of neutral detergent fiber (NDF). Thirty clones each of smooth bromegrass (Bromus inermis Leyss), orchardgrass (Dactylis glomerata L.), and reed canarygrass (Phalaris arundinacea L.) were evaluated in a replicated field study at four growth stages in 2004 and 2005 for NDF, lignin, esterified and etherified ferulates, and 24- and 96-h in vitro NDF digestibility (IVNDFD). Clonal means were generally repeatable across years and harvest dates. Divergent selection created clonal groups with differential lignin and etherified ferulates, but the positive correlation between these two traits was reduced only in smooth bromegrass. Both lignin and etherified ferulates were negatively correlated with 96-h IVNDFD and these relationships were maintained as all three grasses matured. Concentration of NDF was highly correlated with etherified ferulates, making it difficult to partition the impact of components of lignification on IVNDFD.