Phenotypic Plasticity Differs Among Genotypes Within a Forage Legume Species

The rhizoma peanut (Arachis glabrata Benth.) germplasm Ecoturf exhibits phenotypic plasticity, contributing to enhanced persistence and herbage accumulation under frequent, close defoliation. However, plasticity responses of other peanut genotypes have not yet been assessed conclusively. This knowledge would provide useful information regarding their tolerance of a range of defoliation practices. Here, we compared the phenotypic plasticity of three rhizoma peanut cultivars (‘Florigraze’, ‘UF Tito’, and ‘UF Peace’) with Ecoturf during two years when clipped at 2-, 4-, and 8-week defoliation intervals to a 5-cm stubble height. Canopy height, herbage bulk density, mass, accumulation, nutritive value, and persistence-related responses (residual leaf mass, root-rhizome mass, total non-structural carbohydrate [TNC] content and concentration, and canopy cover) were assessed. Florigraze demonstrated lesser plasticity compared with the other genotypes, associated with consistently inferior herbage accumulation due to lesser regrowth capacity and ground cover under frequent defoliation. Ecoturf showed greater adaptive capacity than Florigraze, maintaining similar persistence-related responses across defoliation intervals. Herbage accumulation of UF Peace and UF Tito was similar to that of Ecoturf when clipped every 2 weeks, but UF Peace and UF Tito root-rhizome mass and TNC content were less for the 2- than 8-week defoliation interval. Forage nutritive value of Ecoturf was greatest for the 2-week defoliation interval. Results support previous reports of phenotypic plasticity capability of Ecoturf, but Florigraze is not sufficiently plastic to tolerate long-term frequent, close defoliation. Data suggest newer cultivars UF Peace and UF Tito are likely to be resilient under defoliation management practices recommended for rhizoma peanut.