ABSTRACT The objectives of this study were to estimate genetic parameters and the repeatability coefficient and to select clones of elephant grass from full-sib families. Fifteen clones and two commercial controls were evaluated in a randomized block design with three replications. Three measurements were taken at regular 10-month intervals. Genotypic variance was significant. The observed heritability based on the mean of the genotypes (0.58), coupled with the results of repeatability (0.53) and selection accuracy (0.76), demonstrates that the genotypes performance is constant between measurements. Thus, only three measurements are necessary to reliably select genotypes and obtain real genetic gains with selection. Among the 15 clones evaluated, six showed higher new means than those of the BRS Capiaçu and BRS Canará controls and can be used as parents and/or to compose value for cultivation and use experiments aimed at the release of cultivars for bioenergy production. fullsib full sib families replications 10month month 10 intervals significant 0.58, 058 0.58 , 0 58 (0.58) 0.53 053 53 (0.53 0.76, 076 0.76 76 (0.76) Thus 1 andor or production 05 0.5 5 (0.58 (0.5 07 0.7 7 (0.76 0. (0. (0.7 (0 (

ABSTRACT The mixed-model methodology is an alternative to select genotypes for traits highly influenced by the environment. In addition, this method allows FOR estimating the repeatability coefficient and predicting the number of assessments needed for a selection process to increase reliability. This study aimed to determine the minimum number of evaluations necessary for a reliable selection process and to estimate the variance components used for predicting genetic gains between and within half-sib families of elephant grass ( Cenchrus purpureus (Schumach.) Morrone ) using the mixed-model methodology. Half-sib families were generated using genotypes from the Active Germplasm Bank of Elephant Grass. The experiment was performed in a randomized block design with nine half-sib families, three replicates, and eight plants per plot. We evaluated 216 genotypes (individual plants) of elephant grass. The deviance analysis was carried out, genetic parameters were estimated, gains between and within families were predicted, and repeatability coefficients were obtained using Selegen software. There was genetic variability for selection within the families evaluated. The reliability values found above 60 % for plant height and number of tillers and above 80 % for dry matter yield suggest that only two evaluations are required to select superior genotypes with outstanding reliability. Sixteen genotypes were identified and selected for their productive potential, which can be used as parents in elephant grass breeding programs for bioenergy production. mixedmodel mixed model environment addition halfsib half sib Schumach. Schumach (Schumach. Halfsib Half Grass replicates plot 21 individual out estimated predicted software 6 8 potential production (Schumach 2