Seleção de genótipos de cana-de-açúcar para produção de etanol e silagem

Abstract

Sugarcane is a species that has a high potential of dry matter and energy production per area unit in a single cut, presenting multiple uses, such as ethanol generation and feed production. The objective of this work was to evaluate and characterize sugarcane genotypes for use in animal feed and ethanol production. Twenty-five sugarcane genotypes were evaluated in the experimental field of Embrapa Clima Temperado. For silage production six genotypes and two commercial inoculants were used. The variables evaluated for biomass productivity of the genotypes were: tons of fresh mass per hectare (TMFH), tons of dry mass per hectare (TMSH), tons of total soluble solids per hectare (TSSTH) and tons of stalks per hectare (TCH). To determine chemical-bromatological composition the following analysis were performed: dry matter (MS), crude protein (PB), neutral detergent fiber (FDN), acid detergent fiber (FDA), cellulose (CEL), hemicellulose (HEM), lignin (LIG), total soluble solids content (SST) and ash (CZ). In addition to these variables, in vitro digestibility of dry matter (DIVMS), dry matter losses (PMS) and potential of hydrogen (pH) were used to complement the silage evaluation. The theoretical yield of first generation ethanol (1G) was estimated based on SST, while second generation ethanol (2G) was calculated on the basis of cellulose (ECEL) and hemicellulose (EHEMI) contents, both weighted by stalk yield (TCH) and biomass (TMSH), respectively. The final yield of ethanol per hectare was given by the sum of 1G and 2G. According to the evaluation criteria, the genotypes RB106814, RB106818 and RB106819 stood out for animal feeding. In general the inoculants used for the study of silage did not present expressive gains in quality. For second generation ethanol the genotypes that presented the best theoretical yields were RB106819, RB106818, PRBIO353, PRBIO537 and PRBIO435. Genotypes RB106819 and RB106818 have high yields, suitable for animal feed and production of second generation ethanol as well.