DEFOLIATION EFFECTS ON RHIZOMA PERENNIAL PEANUT RHIZOME CHARACTERISTICS AND ESTABLISHMENT PERFORMANCE

'Florigraze' rhizoma perennial peanut (RPP; Arachis glabrata Benth.) i s a high-quality forage legume vegetatively propagated by rhizomes. Th e impact of prior RPP defoliation management on rhizome chemical compo sition and growth after planting is not understood. These two studies, conducted on a Grossarenic Paleudult soil, evaluated the effects of g razing on (i) rhizome mass, total nonstructural carbohydrate (TNC), an d N concentration, and (ii) rhizome establishment performance followin g planting. Rhizomes for both studies were obtained from pastures prev iously grazed at different combinations of rest interval length (d) an d quantity of residual dry matter remaining after grazing (kg ha(-1)). Specific rest interval-residual dry matter combinations (21-500, 63-5 00, 42-1500, and 63-2500) were chosen to represent a wide range of gra zing severity. An ungrazed treatment (No-Grz) was also included. Avera ge rhizome mass was greatest (17.0 Mg ha(-1)) for No-Grz and declined as grazing severity increased from 63-2500 (9.4 Mg ha(-1)) to 21-500 ( 2.3 Mg ha(-1)). Grazing treatments also provided rhizome planting mate rial with a wide range of TNC concentration (62-301 g kg(-1)) and N co ncentration (12.7-22.1 g kg(-1)). Greatest concentrations were observe d for No-Grz and less severely grazed pastures. Planting rhizomes with initial TNC greater than or equal to 228 g kg(-1) and N greater than or equal to 20 g kg(-1) resulted in the greatest seasonal accumulation of both rhizome and shoot mass. Planting rhizomes with low TNC (62 g kg(-1); 21-500) resulted in stand failure in a drought year (1990). Rh izomes with higher TNC (139 g kg(-1); 63-500) produced shoots that sur vived drought conditions but growth rates were relatively slow. We con clude that grazing affects chemical composition of RPP rhizomes and th at chemical composition of planting material is a major determinant of RPP establishment success.