Stem Anatomy of Switchgrass Plants Developed by Divergent Breeding Cycles for Tiller Digestibility

Switchgrass (Panicum virgatum. L.) is an important perennial forage and biomass crop that is native to the temperate prairies of the North America east of the Rocky Mountains. Breeding for improved forage in vitro dry matter digestibility (IVDMD) has been conducted using post-heading, whole-tiller IVDMD as the selection criterion (Hopkins et al., 1993; Vogel et al., 2002). One breeding cycle (C-1) for low IVDMD and three cycles for high IVDMD (C1, C2, C3) were completed in a switchgrass population adapted to the USA mid- latitudes. Sward trials demonstrated that whole plant IVDMD had been improved (Hopkins et al., 1993). This study reports on changes in plant anatomy of plants from populations divergently bred for whole tiller IVDMD