Evaluation of productivity of sweet potato genotypes for first and second generation bioethanol production

Abstract

The increased supply of ethanol fuel and its spread as an alternative to fossil fuels depend on the exploration of biomasses that can be regarded as alternatives to sugarcane and maize. In this study, the agricultural productivity and the potential for production of ethanol from roots and the aerial portion of twenty sweet potato genotypes were evaluated. The roots and branches were harvested 180 days after planting. Starch, hemicellulose, cellulose, lignin and soluble sugars from sweet potato roots or branches were determined and expressed as percentage of dry matter produced per hectare. The genotype UFVJM 28 stood out for the production of root and branches (fresh material), yielding 43.5 and 31.7 t ha-1, respectively. The roots of the Palmas, Batata Mandioca, Cariru Vermelha and UFVJM 45 genotypes had the highest total soluble sugar concentrations, between 4.1 and 5.4%. The enzymatic digestibility for starch contained in the roots ranged from 58.2 to 91.2%, and when related to the cellulose contained in the branches, it ranged from 14.2 to 42.4%. The estimates for the production of ethanol from the roots ranged between 1120 and 4940 L ha-1. The estimated production of bioethanol from sweet potato branches of the genotypes varied from 240 to 995 L ha-1. Considering the combined use of roots and branches, at least four sweet potatoes genotypes presented a potential for ethanol production greater than 4000 L ha-1 in a 180-day cycle.