Influence of summer fallow on aromatic secondary products in sugarcane (Saccharum spp. hybrids)

Cover crops are sustainable alternatives to current fallow practices (cultivation with and without synthetic herbicides) for sugarcane cultivation in Louisiana. Potential benefits of such ecological approach include additional profits from harvested cash crops, pest/disease management, and retention of highly erodible alluvial soils. This study investigated the impact of conventional (tillage and glyphosate) and newer (sweet sorghum and soybean cover crops) fallow practices on the chemical quality of sugarcane juice extracted from the first-ratoon of four commercial cultivars. Although antioxidant is expected to influence sucrose yield, genotype-dependent polyphenol composition in sugarcane juice is largely unknown. The cultivar HoCP 09-804 accumulated the highest sucrose, cis-aconitic acid, total organic carbon, and fluorescent polyphenols. Oppositely, cultivar HoCP 96-540 produced the lowest sucrose and polyphenols, and highest tryptophan-like fluorophore. Partial least squares calibration was developed to predict the amounts of secondary products in juice using low-cost aqueous UV/ visible spectrophotometry with the ultimate goal of providing QA/QC protocols for the renewable chemical feedstocks (aconitic acid) and food additives (polyphenols) at biorefineries. Different fallow practice had no significant effects (p < 0.05) on the chemical composition of sugarcane juice. The results will allow sugarcane growers to maximize the sucrose yield, regardless of the summer fallow practice implemented.