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Defoliation Effects on Rhizoma Perennial Peanut Rhizome Characteristics and Establishments Performance

Rice, R. W., Sollenberger, L. E., Quesenberry, K. H., Prine, G. M., French, E. C.
Crop science 1995 v.35 no.5 pp. 1291-1299
Arachis glabrata, forage crops, pasture plants, defoliation, rhizomes, nitrogen content, carbohydrates, mortality, drought, dry matter accumulation, shoots, chemical constituents of plants
‘Florigraze’ rhizoma perennial peanut (RPP; Benth.) is a high-quality forage legume vegetatively propagated by rhizomes. The impact of prior RPP defoliation management on rhizome chemical composition and growth after planting is not understood. These two studies, conducted on a Gressarenic Paleudult soil, evaluated the effects of grazing on (i) rhizome mass, total nonstructural carbohydrate (TNC), and N concentration, and (ii) rhizome establishment performance following planting. Rhizomes for both studies were obtained from pastures previously grazed at different combinations of rest interval length (d) and quantity of residual dry matter remaining after grazing (kg ha). Specific rest interval-residual dry matter combiuatious (21-500, 63-500, 42-1500, and 63-2500) were chosen to represent a wide range of grazing severity. An ungrazed treatment (No-Grz) was also included. Average rhizome mass was greatest (17.0 Mg ha) for No-Grz and declined as grazing severity increased from 63-2500 (9.4 Mg ha) to 21-500 (2.3 Mg ha). Grazing treatments also provided rhizome planting material with a wide range of TNC concentration (62-301 g kg) and N concentration (12.7-22.1 g kg Greatest concentrations were observed for No-Grz and less severely grazed pastures. Planting rhizomes with initial TNC ≥ 228 g kg and N ≥ 20 g kg resulted in the greatest seasonal accumulation of both rhizome and shoot mass. Planting rhizomes with low TNC (62 kg; 21-500) resulted in stand failure in a drought year (1990). Rhizomes with higher TNC (139 g kg; 63-500) produced shoots that survived drought conditions but growth rates were relatively slow. We conclude that grazing affects chemical composition of RPP rhizomes and that chemical composition of planting material is a major determinant of RPP establishment success.