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

Authors: Uchimiya, Sophie; Spaunhorst, Douglas

Submitted to: Journal of Agriculture and Food Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2020
Publication Date: 8/14/2020
Citation: Uchimiya, M., Spaunhorst, D.J. 2020. Influence of summer fallow on aromatic secondary products in sugarcane (Saccharum spp. hybrids). Journal of Agriculture and Food Research. 2:100064. https://doi.org/10.1016/j.jafr.2020.100064.
DOI: https://doi.org/10.1016/j.jafr.2020.100064

Interpretive Summary: There is a shift towards more sustainable commodity production in the U.S. and worldwide. Technology transfer is often the bottleneck in adaptation of sustainable practices by growers. This study showed that the quality of harvested sugarcane is maintained under sustainable summer fallows employing sweet sorghum and soybean cover crops. Results indicate added profits from harvested break-crops as well as improved soil health and lower costs for synthetic chemical applications.

Technical Abstract: 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 (cultivation and glyphosate) and newer (sweet sorghum and soybeans) fallow practices on the chemical quality of sugarcane juice extracted from the first-ratoon of four commercial cultivars. Current knowledge is nonexistent on the structural composition of polyphenolic and metal-chelating secondary products in sugarcane juice and its genotypic dependence, despite putative roles of secondary products as antioxidant influencing the sucrose yield. 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.