Seleção de genótipos de sorgo sacarino com base no desempenho agroindustrial e no potencial fermentativo

Abstract

The sweet sorghum crop [Sorghum bicolor (L) Moench] contains agroindustrial traits that turn it into an economic feedstock that is promising for the production of ethanol. The aim of this study was the evaluation of the agroindustrial performance and the maturation of elite genotypes of sweet sorghum, as well as the fermentative potential when it was submitted to two types of yeasts. The maturation curve experiments were performed during the seasons 2016/2017 in the localities of Lavras / MG, Sete Lagoas / MG, and Sinop / MT. The genotypes used were the lines: BRS508, CMSXS643, CMSXS646, CMSXS647 and the hybrids CV198, N31L5010, 201549B014, 201610B033, 201610B081, and 201610B095, which were harvested at 100, 107, 114, 121, 128, 135, and 142 days after sowing. The mensuration traits were: plant height, juice extraction, fresh biomass production, total soluble solids content, and tons of brix per hectare. The industrial use period (PUI) was 20 days, occurring between 110 and 130 days after sowing. The fermentation process was performed in the Laboratory of Physiology and Genetics of Microorganisms, in the Agricultural Microbiology sector of the Federal University of Lavras. It was measured the sugar consumption, performed by two Saccharomyces cerevisae yeast (LNF Ca11 and BY) of the genotypes BRS508, CMSXS643, CMSXS646, CMSXS647, and 201459B014. These genotypes presented higher levels of total soluble solids content in maturation curve trials in Lavras. TSS levels were measured at baseline (T0) and 24 h (T24) after inoculation. The selective precision at the genotype level ranged from 90.25% to 98.31% in the maturation curve trials. Differences among genotypes were detected for all traits, emphasizing the genotypes BRS508, CMSXS646, and CMSXS647 for TSS. There was no interaction between genotypes and harvesting time. The BY yeast was the most effective considering the fermentation process. Whereas for the genotypes, the CMSXS647 presented the highest consumption relative to the TSS by the yeasts, meaning that this genotype and this yeast might be promising for the ethanol production. There was interaction between sorghum genotypes and yeasts. This fact evidenced the existence of specificity for fermentation purposes. Nevertheless, it was observed a superiority of the BY yeast that demonstrated the possibility of identification of yeasts with wide uses for different genotypes of sweet sorghum. The CMSXS647, CMSXS643, and CMSXS646 genotypes are the most promising sweet sorghum genotypes for ethanol production taking into consideration both agronomic performance and fermentative potential.