Qualidade energética da madeira de cinco genótipos de Eucalyptus plantados em perímetro irrigado.

Abstract

The use of wood forest products from cultivated species as an energy source has been proven to be a crucial option to minimize the suppression of native vegetation, as it is the case with plantations of Eucalyptus genus. In addition, wood is a renewable resource with several industrial applications, especially in the production of charcoal. Within this context, particularly for bioenergy, species of the Eucalyptus genus stand out. In this context, this research aimed at evaluating the energy potential of wood and charcoal from five Eucalyptus genotypes (AEC 1528, GG 680, GG 702, VE 38 and VE 41) planted in two irrigation periods. Four trees per clone were randomly collected, with good health, of approximately 11 years of age. A 5.0 cm thick disc was removed from each tree, at positions 0 (base), 20, 40, 60 and 80% of the commercial height, considered a minimum diameter of 5.0 cm. A completely randomized experimental design (CRD) was used, where a Tukey test (p ≤ 0.05) was performed, being used for variables that were significant by the F test (p ≤ 0.05). Pearson's linear correlation was also employed. The results showed that the basic wood density of the five clones was statistically similar in the two irrigation periods, however, the GG 702 clone was the one that presented the highest value (0.663 g cm -3). For CF values, VE 41 presented the highest percentage (16.61%). Regarding lignin levels, the AEC 1528 genotype demonstrated the highest results in both water conditions. The GG702 clone contained the highest energy density (ED) values also in the two irrigation conditions applied. As for Fuel Value Index (FVI), the GG702 genetic material presented greater results when irrigated for up to 36 months (4218.17). The average values of gravimetric yield in charcoal (GY) varied from 37.66% to 41.16%. Regarding the apparent density of charcoal, the AEC 1528 clone contained the highest value (0.43 g cm-3). The VE 41 and AEC 1528 hybrids obtained the highest values for the higher heating value of charcoal (6914.58 and 6921.19 Kcal kg-1) respectively. A positive correlation was observed between the Gross Calorific Value (GCV) and the fixed carbon content of the wood in both irrigation periods. The irrigation period did not influence the wood density of the evaluated clones and the five clones demonstrated to be suitable for energy use, regardless of the water regime.