Variations in Primary and Secondary Metabolites of Panicum maximum under Diverse Wastewater Pollution Conditions

Panicum maximum is planted extensively in tropical and subtropical areas, due to its high-quality forage and high biomass yield. This study aims to assess the varied metabolic dynamics of P. maximum subject to different pollution-related wastewater levels, thus providing information for sustainable agriculture and soil restoration. We analyzed the primary and secondary metabolites in P. maximum subject to two different types of polluted wastewater (WW), compared to a control group. The alterations observed in the metabolite profiles were affected by several factors, including nutrient imbalances and oxidative stress induced by heavy metal accumulation. Initially, the increased nutrient availability stemming from wastewater treatment promoted plant growth; however, this positive effect was later diminished by the adverse impacts of heavy metals, which generated oxidative stress, resulting in metabolic disturbances and a decrease in the plant biomass. Importantly, the substantial increase in antioxidant enzymes, related to primary (e.g., sugars) and secondary metabolites (e.g., phenolics and flavonoids), underscores plants’ adaptive strategies to cope with stress. The increased biosynthesis of flavonoids and phenolic compounds is a protective mechanism against oxidative stress, which also improves the antimicrobial activity, following the activation of key biosynthetic pathways involved in their synthesis. These complex interactions among diverse metabolites suggest that plants exposed to polluted wastewater use various biochemical strategies to increase both their survival and defenses against pathogens. Collectively, these findings emphasize the significance of understanding how wastewater management practices can affect plant health, metabolic responses, and the broader implications for food safety and ecosystem stability.