Crescimento, produção e qualidade da biomassa em variedades de capim-elefante na zona da mata de Alagoas

Abstract

The objective of this research was to evaluate the growth, production and biomass quality of three genotypes of elephant grass (Cenchrus purpureus (Schumach.) Morrone) cultivated in the Zona da Mata region of the State of Alagoas for energy use of biomass, using semi-empirical growth models. Three elephant grass genotypes (BRS Capiaçu, Madeira and Pasto Panamá) cultivated in an experimental area located at the Center for Agricultural Sciences of the Federal University of Alagoas (CECA/UFAL), located in the municipality of Rio Largo, State of Alagoas, were evaluated. Eight different cutting ages were evaluated (30, 60, 90, 120, 150, 180, 240 and 300 days after cutting) with corresponding growth assessments with analyzes of leaf area index (LAI), average plant height, the average diameter of the culms and the average number of tillers per linear meter. In addition to these characteristics, the accumulation of shoot biomass was determined and the energy quality of the biomass was characterized by determining the concentrations of carbon, nitrogen, cellulose, hemicellulose, lignin and ash. Semi-empirical growth models (logistic, PicoLog and regression) were used to process the data, which were efficient to estimate the majority of analyzed variables. The results showed that the three varieties of elephant grass present similar phenological and productive behavior, whose maximum growth period occurs up to 120 days after cutting, with significant increases in biomass accumulation. The tillering rates reaches maximum levels at 30 days after cutting, suffering reductions and stabilization from 60 days after cutting. The ash content decreases at 60 days after cutting in the BRS Capiaçu and Pasto Panamá varieties and at 90 days after cutting in the Madeira variety. Cellulose levels increases and nitrogen levels decreases at 60 days after cutting, while lignin levels increases at 120 days after cutting in the Madeira and Pasto Panamá varieties and at 150 days after cutting in the BRS Capiaçu.

Palavras-chave: Cenchrus purpureus (Schumach.) Morrone, plant development, Forage Production, Northeast Coastal Tablelands.