Effects of Digestion on Germination of Native Grasses of the Southern Great Plains

Abstract

Rehabilitating rangelands through native plantings can be an expensive and risky endeavor that requires extended time periods with low success rates. Economical methods of seed dispersal through ruminant ingestion have been tested unsuccessfully in the Northern Great Plains, but this approach has not been evaluated in depth in the Southern High Plains. Scarification during digestive processes could potentially improve the germinability of native grass species possessing low germination rates and assist in approving plant establishment. To determine how various digestive phases affect seed germinability, we evaluated how simulated digestion affected germination parameters for sideoats grama (Bouteloua curtipendula [Michx.] Torr.), buffalograss (Bouteloua dactyloides [Nutt.] J.T. Columbus), blue grama (Bouteloua gracilis [Willd. ex Kunth] Lag. ex Griffiths), silver bluestem (Bothriochloa laguroides [DC.] Herter), green sprangletop (Leptochloa dubia [Kunth] Nees), and plains bristlegrass (Setaria leucopila [Scribn. & Merr.] K. Schum.). Seeds were incubated in either 1) rumen fluid for 48 h, 2) acid-pepsin solution for 2 h, or 3) rumen fluid for 48 h, followed by acid-pepsin solution for 2 h. Statistical procedures were performed for all germination parameters using general linear mixed models. Only buffalograss demonstrated the ability to survive the full digestive process, having greater germination than all other species exposed to the rumen fermentation and acid-pepsin treatment (P ≤ 0.05). Acid-pepsin treatment maintained or increased germination relative to the control for all species (P ≤ 0.001). Depending on the species, digestive treatments altered the germination profile relative to the nondigested control. Results from this study indicate that seed dispersal via ruminants is not an effective option for most of the species tested, with only buffalograss being a potential candidate. In contrast, endozoochory by monogastric species may increase the success of seed establishment; however, this could support the migration of noxious or invasive species that can greatly alter vegetative communities.