Exploring the Relationship of Growth Habit and Response to Grazing Management within Arachis Glabrata.

Growth habit affects plant response to grazing. Rhizoma peanut (RP; Arachis glabrata Benth.) is considered persistent under grazing, but growth characteristics vary among RP lines. The cultivar ‘Florigraze’ demonstrated grazing tolerance across a range of grazing practices, but close, frequent grazing reduced herbage accumulation (HA) by 70% and percentage RP from 90 to 30 over 2 yr. Ecoturf RP is a decumbent type and may tolerate grazing well. The objective of this study was to 1) determine how grazing management affects HA and persistence of Ecoturf, 2) explain these responses by assessing leaf and storage organ characteristics, and 3) compare Ecoturf response to grazing with the more upright Florigraze. Treatments were two post-grazing stubble heights (SH; 4 and 8 cm) and three regrowth intervals between grazing events (RI: 1, 4, and 7 wk). For the 4-cm SH, HA decreased (linear and quadratic) with increasing RI in both years, and the greatest decrease occurred between 1 and 4 wk. For the 8-cm SH, the effect of RI on HA was less pronounced than for 4 cm in the first year and there was no effect in Year 2. Why was Ecoturf HA high when grazed weekly to 4-cm SH? Residual leaf mass after grazing to 4-cm SH was greatest for the 1-wk RI and decreased linearly as RI increased to 7 wk. Thus, Ecoturf demonstrated phenotypic plasticity when grazed frequently and closely, protecting leaf area close to the soil, something that Florigraze could not do. Although Ecoturf rhizome-root mass and non-structural carbohydrate pool were greater for 7- than 1-wk RI and for 8- than 4-cm SH, these responses actually increased during the 2 yr of study for the 1-wk RI and 4-cm SH. Ecoturf’s decumbent growth habit affords considerable protection against overgrazing, thus permitting different grazing management than more upright types.