Effects of Grazing Management Strategies On Sward Responses of Rhizoma Peanut Genotypes.

Recently released genotypes of rhizoma peanut (Arachis glabrata; RP) represent a range of growth habits which may affect their persistence under grazing. Their response to grazing, however, has not yet been evaluated and optimal management practices have not been defined. The objective of this study was to quantify sward canopy responses to grazing frequency and intensity in order to assess relative grazing tolerance among RP genotypes. Treatments were the factorial combinations of four RP genotypes [Florigraze, UF Peace, UF Tito, and Ecoturf], two grazing intensities (50 and 75% canopy removal), and two grazing frequencies (3 or 6 wk), arranged in two replications of a randomized complete block design. All plots were fertilized according to soil test recommendations with P and K. Herbage accumulation (HA) was estimated throughout the grazing season from June to October 2012. No differences were observed among genotypes for total-season HA, and the seasonal average was ≥ 7,950 kg ha^-1 for all entries. Percentage RP ground cover and weed frequency were measured at the beginning and end of the grazing season in June and October 2012. Mean ground cover across the season was greater for Ecoturf (95%) compared with all other genotypes, and less weed frequency was associated with the 6-wk than 3-wk grazing frequency (34% vs. 45%, respectively). Pregraze light interception (LI) and leaf-to-stem ratio, and postgraze residual leaf area index (RLAI) were quantified during July and August 2012. Grazing frequency affected LI, with the 6-wk treatment having greater LI (91%) compared with the 3-wk interval (85%). A genotype effect was observed for postgraze RLAI where Ecoturf had greater RLAI than Florigraze and UF Tito (1.2 vs. 0.81 and 1.05, respectively). UF Peace was not different from Ecoturf and UF Tito, but had greater RLAI (1.19) than Florigraze. Residual leaf area was less for 75 than 50% canopy removal (0.89 vs. 1.23, respectively). Pregraze leaf-to-stem ratio was greater for Ecoturf (1.75) compared with UF Peace, Florigraze, and UF Tito (mean RLAI 1.42, respectively). The 3-wk grazing frequency resulted in lesser leaf-to-stem ratio compared to the 6-wk frequency (1.41 vs. 1.59, respectively). These data suggest that the prostrate growth habit of Ecoturf is associated with greater ground cover and leaf-to-stem ratio before grazing and RLAI following defoliation events. Greater pregraze LI and less weed frequency with the 6- vs. 3-wk grazing frequency and greater RLAI with 50 vs. 75% removal suggest that these levels of the treatment factors likely favor RP persistence.