ABSTRACT In experiments with selection of perennial plants, the initial performance is expected to be maintained throughout the productive life. The probability of repeating the agronomic response can be evaluated by the repeatability coefficient. The objective was to estimate repeatability coefficients of agronomic characteristics in Panicum maximum Jacq. using different methods and identify the best combinations between harvests according to the genotypic stabilization. Seventeen genotypes were evaluated in a randomized complete block design with three replicates. The coefficients of repeatability were estimated by the methods: ANOVA, structural analysis based on the mean of the correlation coefficients (SACOR), analysis of principal components based on the covariance matrix (PCCOV) and correlation matrix (PCCOR). In the genotypic stabilization, coefficients estimated by ANOVA and PCCOR were used. For total DM, repeatability coefficients ranged from 0.3500 to 0.4300 by the ANOVA and PCCOR methods, respectively. High repeatability coefficients were found for the characteristic leaf DM, while low coefficients were observed for leaf and stem percentages and leaf:stem ratio. For the genotypic stabilization of total DM and leaf:stem ratio, the best coefficients were observed for the combination of harvests 5 to 8. There are variations in the estimate of repeatability by different methods and the highest coefficients were those of the principal components based on the correlation and covariance matrices. For the genotypic stabilization, the best coefficients of repeatability and determination were observed for the harvests performed in the second rainy period.

Objetivou-se com esta pesquisa avaliar a resposta produtiva e os ciclos de colheita do capim-marandu irrigado e adubado com combinações contendo ureia e esterco bovino em diferentes períodos. Utilizou-se delineamento em blocos casualizados, em esquema de parcelas subdivididas no tempo com 5 tratamentos e 5 repetições. Foram testados cinco níveis de substituição da ureia por esterco bovino (0; 25; 50; 75 e 100% de esterco bovino) em três épocas de crescimento. O acúmulo de forragem total e de folhas com a inclusão do esterco em substituição a ureia reduziu em 59,24% e 61,23%, respectivamente. A produção acumulada e o número de ciclos de colheita decresceram com a inclusão de esterco bovino, de 44,7% e 46,66% respectivamente. As porcentagens de folha, colmo e morto foram influenciadas somente pela época, sendo os melhores resultados observados no segundo período. A produção acumulada e o número de ciclos de colheita decresceram com a inclusão de esterco bovino. A produção de forragem e os ciclos de colheita são afetados negativamente pela inclusão do esterco em substituição à ureia.

The objective of this work was to evaluate the productive response and harvest cycles of irrigated and fertilized marandu grass with combinations containing urea and bovine manure in different periods. A randomized complete block design was used, in a plot scheme subdivided in time with 5 treatments and 5 replications. Five levels of urea replacement by bovine manure (0, 25, 50, 75 and 100% bovine manure) were tested at three growing seasons. The accumulation of forage and leaves with the inclusion of manure in substitution of urea decreased by 59.24% and 61.23%, respectively. The accumulated production and the number of harvest cycles decreased with the inclusion of bovine manure, 44.7% and 46.66%, respectively. The percentages of leaf, stem and dead were influenced only by the season, and the best results were observed in the second period. The accumulated production and the number of harvest cycles decreased with the inclusion of bovine manure. Forage production and harvest cycles are negatively affected by the inclusion of manure as a substitute for urea.