Repeatability and minimum number of evaluations for morpho-agronomic characters of elephant-grass for energy purposes.

Abstract

ABSTRACT Due to the need to promote information relevant to elephant-grass breeding programs for energy purposes, this work aimed to estimate the coefficient of repeatability of the main morpho-agronomic characters and to predict the minimum number of cuts required for selection with greater efficiency. A total of 73 elephant-grass genotypes were evaluated in a randomized block design, in a subdivided plot scheme with two replicates. Nine cuts were performed at six-month intervals, from June 2012 to December 2016, in the municipality of Campos dos Goytacazes, RJ. We estimated the repeatability coefficients for dry matter yield (DMY), number of tillers (NT), plant height (PH), stem diameter (SD) and leaf blade width (LBW), using the methods of analysis of variance, principal components and structural analysis. At least nine, three, six, six and three cuts should be performed, considering the DMY, NT, PH, SD and LBW characteristics, respectively, to predict the true value of the genotypes with 80% reliability