Glyphosate, an agricultural input primarily used for weed control, is a broad-spectrum foliar herbicide. It indiscriminately eliminates any plant it comes in contact with, thus efficiently suppressing weed growth that could compete for space and nutrients, thereby affecting crop yields. Its effectiveness, low cost, and ease of application have led to its widespread usage in agriculture worldwide.
In Mexico, various commercial products, including Cacique, Faena, Trinchera, Látigo, Herbifox, Mochilero, Secafín, Bombazo, Torbellín, Aquamáster, and Potro, contain glyphosate. The herbicide acts by inactivating an enzyme only found in plants and certain bacteria, which is critical to the synthesis of essential amino acids. This enzyme disruption prevents plants from producing the necessary proteins for growth, eventually leading to their demise.
Interestingly, glyphosate isn't just used as a weed killer but also as a chemical ripener in sugarcane (Saccharum officinarum) cultivation. Sugarcane farming is a significant economic and social activity in Mexico, placing the country among the top ten sugarcane producers globally. The ripening stage of the sugarcane plant, when it accumulates most sugars, is key to the cultivation process. However, the growth of lateral stems at this stage can reduce the sugar concentration in the main stem, posing a challenge for the final harvest.
Several strategies were explored from the 1960s to address this issue, but it was not until the 1970s when the use of compounds such as ethrel, glyphosate, moddus, and polaris showed promise. Glyphosate, in particular, effectively induced sucrose accumulation during the harvest of sugarcane. Research by Pincelli-Souza et al. (2020) and De Almeida Silva et al. (2022) further showed that glyphosate applied at low doses can stimulate physiological processes that promote sucrose production in sugarcane.
However, glyphosate's global usage in agriculture, especially since the 1990s, has stirred up controversy over its biosafety and ecological impact. Its residue on fruits and vegetables, as well as in soil and water, has raised concerns about the effects on human health and other species. There is also the issue of glyphosate negatively affecting the regrowth of some sugarcane varieties.
In light of these concerns, Mexico has been exploring alternatives to reduce glyphosate use in food production, striving for food sovereignty. Collaborating in this effort are the Laboratory of Plant Physiology and Molecular Biology and the Laboratory of Industrial Biotechnology of the Center for Research in Food and Development (CIAD). Together with the Center for Research and Assistance in Technology and Design of the State of Jalisco (Ciatej) They evaluated three glyphosate alternatives as chemical sugarcane ripeners, each with a low environmental impact and produced by Mexican companies.
These alternatives include products with active ingredients like chitosan, potassium phosphite, and carboxylic acids. Both field and lab tests were conducted to determine these products' effectiveness in promoting sucrose accumulation in sugarcane and deciphering their possible mechanisms of action.
Results indicated that all three alternatives had a positive impact on sugar accumulation compared to a control, with chitosan and carboxylic acids showing the best results. The carboxylic acid-based product specifically increased the sucrose content per 100g of sugarcane by 1.6 times after just 14 days, with chitosan and potassium phosphite-based products following closely behind.
Lab tests also revealed that these alternatives stimulated the synthesis and transport of sugars within the plant. They caused an accumulation of sucrose in mature leaves and activated genes involved in sugar synthesis (SUS1) and transport (SUT2). This research shows promising results for these alternatives, as they have the potential to enhance sugar synthesis and transport within the plant at various stages and levels.
The ongoing quest for more sustainable agricultural practices continues. These findings mark a significant step towards reducing glyphosate usage, potentially offering safer and more eco-friendly solutions to improve productivity in sugarcane farming and beyond.