Rhizoma peanut herbage and root–rhizome responses to extended regrowth periods

Abstract

AbstractRhizoma peanut (RP; Arachis glabrata Benth.) is an important species for hay production in the U.S. Gulf Coast region; however, frequent summer rains and high humidity often preclude optimal harvest intervals. Extended regrowth periods are common on‐farm but data are limited assessing their impact on plant responses. The objective was to compare above‐ and belowground responses of 14 RP entries to defoliation frequency during 3 yr. Frequencies were one (1×) and two (2×) harvests per year, reflecting common producer practice. Annual herbage accumulation (HA) was approximately twice as great for 2× than 1× (10.5 vs. 5.4 Mg ha−1 yr−1, respectively). An exception was experimental line Beta for which HA did not differ between frequencies, perhaps because of Beta's greater disease tolerance that minimized leaf shedding. The 2× frequency also had greater herbage crude protein concentration than 1× (150 and 125 g kg−1, respectively). Reductions in HA and nutritive value for 1× vs. 2× were generally greatest for upright‐growing entries. Plots cut once per year had 54% more root–rhizome mass than those cut twice (8.5 vs 5.5 Mg ha−1, respectively) but defoliation frequency did not affect root–rhizome total nonstructural carbohydrate (TNC) concentration. Results indicated RP hay producers should harvest both summer and fall (2×) at minimum. If rhizomes are to be dug for subsequent vegetative propagation, defoliation should be limited to once annually to avoid reduction in root–rhizome mass.