Caracterização e seleção de genótipos de batata-doce para a produção de etanol em função de diferentes épocas de colheita

Abstract

Sweet potato (Ipomoea batatas) stands out as an alternative crop for ethanol production due to its high dry matter and starch content, high root yield, and broad adaptability to different environments. Moreover, harvest time directly affects sugar concentrations in the roots and the quality of the raw material, significantly influencing fermentation yield and efficiency. This study aimed to characterize and select sweet potato genotypes for ethanol production across different harvest times. The experiment was carried out at CDTT/ESAL/UFLA, in the municipality of Ijaci-MG, during the 2023/24 season. A randomized block design was used in a 15×3×2 factorial arrangement, comprising 10 experimental genotypes from UFLA (UFLA 527, UFLA 1192, UFLA 286, UFLA 1476, UFLA 516, UFLA 1074, UFLA 210, UFLA 1377, UFLA 397, and UFLA 1404) and 5 commercial cultivars (UFLA R1440, UFLA-B556, BRS Amélia, BRS-Cotinga, and BRS-Rubissol), three harvest times (90, 120, and 150 days), and two growing seasons (summer and winter), with three replications. Evaluations included total root yield, root dry mass yield, starch production, starch yield, reducing sugars, titratable acidity, pH, ethanol production, and ethanol yield. The cultivar UFLA R1440 and the genotypes UFLA 1192 and UFLA 286 achieved higher total root yields in the summer crop, while UFLA 1404 and UFLA 397 excelled in the winter crop. For root dry mass yield, UFLA R1440 and UFLA 1192 showed superior performance in the summer, whereas UFLA 1404 reached the highest yield in the winter. Considering starch yield (t ha⁻¹), UFLA R1440 and UFLA 1192 again stood out across harvest times. UFLA R1440 also achieved the highest ethanol yield (L ha⁻¹). Ethanol production (L t⁻¹ of root) and reducing sugars were not significantly affected by harvesting at 120 and 150 days. Positive genotypic correlations were observed between root dry mass yield × total root yield, starch yield × total root yield, ethanol yield × total root yield, starch yield × ethanol yield, total reducing sugars × total root yield, total reducing sugars × root dry mass yield, and total reducing sugars × starch yield. Overall, UFLA R1440 is recommended for ethanol production, with an ethanol yield potential of 8,473.84 L ha⁻¹ and a root yield of 52.78 t ha⁻¹.