Pre-breeding of elephant grass for energy purposes and biomass analysis in Campos dos Goytacazes- RJ, Brazil

The objective of this study was to evaluate the morpho-agronomic traits of eighty five accessions of elephant grass (Pennisetum purpureum Schum.) from the germplasm bank located at the Experimental Field of the State Center for Research on Bioenergy and Waste Recovery (Centro Estadual de Pesquisa em Agroenergia e Aproveitamento de Residuos). The experimental design was a randomized block with two replicates, in an annual-harvest system. The evaluated traits were: percentage of dry matter (%DM), dry matter yield (DMY), number of tillers per linear meter (NT), plant height (HGT), stem diameter (SD), leaf blade width (LW) and leaf blade length (LL). Each cut and variable underwent variance analysis and the Scott-Knott test (P<0.05). Tocher’s optimization method, Mahalanobis distance and canonic variables were used for the multi-traits, and importance of the characters in the canonic variables. The following elite genotypes were identified by the Scott-Knott test at 5%: Rico 534-B, Taiwan A-144, Napier S.E.A., Mole de Volta Grande, Teresopolis, Taiwan A-46, Duro de Volta Grande, Turrialba, Taiwan A-146, Cameroon Piracicaba, Taiwan A-121, P241 Piracicaba, Elefante Cachoeira Itapemirim, Guaco/I.Z.2, Cameroon, IJ 7126 cv EMPASC 310, IJ 7139, Australiano, 10 AD IRI, and Pasto Panama. By the analysis of the canonic variables, the first two accumulated 64.6457% of variance. Regarding the relative importance of the evaluated traits, the leaf blade length at cut two was the most important. By Tocher’s optimization method, the eighty five accessions were divided into twenty five groups, indicating a high variability in the germplasm bank.   Key words: Pennisetum purpureum, Tocher’s optimization, Mahalanobis distance, elephant grass.