Genotypic superiority and repeatability coefficient in elephant grass clones for forage production via mixed models

Elephant grass ( Cenchrus purpureus (Schumach.) Morrone) is recognized as a forage plant with high dry matter production potential and high nutritional value, can be used in different ways, which include grazing material, grassland formation, and use as preserved forage. The selection of the elephant grass genotypes most adapted to the soil-climatic conditions of the northern region of the state of Rio de Janeiro, Brazil, can increase forage supply, especially in the dry season, thus mitigating the effects of production seasonality in that region. This study proposes to examine the genotypic superiority of elephant grass genotypes based on productivity, adaptability, and stability; predict genetic gains for forage production-related traits; and infer the minimum number of evaluations necessary to obtain greater gains with selection. The experiment involved 53 elephant grass genotypes in a randomized-block design with two replications. Dry matter yield, number of tillers per clump, plant height, and stem diameter were measured. The statistical analysis was carried out via mixed models (REML/BLUP), using the computational resources of Selegem software. The obtained repeatability values demonstrate that the genotypes’ performance is constant across measurements, with seven measurements required to reliably select elephant grass clones. There was agreement between the HMGV, RPGV, and HMRPGV statistics in choosing the most productive, adaptable, and stable genotypes. Clones Mercker 86 México, Mercker Comum, Gramafante, Guaçu/I.Z.2, and Pasto Panamá were the most productive, adaptable, and stable.