Medicinal and aromatic plants as climate-smart crops: case studies on Pelargonium graveolens and Viola odorata under Egyptian conditions

Abstract

Medicinal and aromatic plants (MAPs) represent high-value agricultural commodities that provide economic returns through essential oil production while potentially contributing to climate change mitigation via photosynthetic carbon sequestration and oxygen release. Despite their recognized economic importance, few studies have systematically quantified the net environmental performance of MAP cultivation and processing within integrated climate mitigation frameworks. This study evaluated the carbon footprint, oxygen production, and CO₂ absorption of two commercially important MAPs—Pelargonium graveolens (geranium) and Viola odorata (violet)—cultivated under Egyptian field conditions, using life cycle assessment methodology with system boundaries from field operations through extraction. Primary data were collected from commercial farms (geranium: 37 feddans aggregated; violet: 1 feddan) over complete growing cycles. Geranium (6-month season) demonstrated net climate-positive performance with a negative carbon footprint of − 375 kg CO₂-eq. per feddan per season, producing 54,324 m³ of oxygen and absorbing 155,632 kg CO₂ during growth, with photosynthetic uptake exceeding all process emissions (fuel, irrigation electricity, fertilizers, and composting). In contrast, violet (12-month annual cycle) exhibited a positive footprint of + 15,972 kg CO₂-eq. per feddan annually, despite generating 11,148 m³ oxygen and absorbing 12,700 kg CO₂, primarily due to its fuel-intensive solvent extraction process that accounts for 97.3% of total emissions. Monte Carlo uncertainty analysis (N = 10,000 simulations) confirmed geranium’s robustness as a net carbon sink (probability 67.4%) while violet remained a consistent carbon source under current extraction practices. Scenario modeling demonstrated that substituting fossil fuel with solar thermal energy or biogas-derived heat for violet distillation could reduce net emissions by 50–100%, potentially shifting the crop from carbon source to near-neutral status. These findings indicate that MAPs can function as climate-smart crops when cultivation practices are coupled with renewable energy integration in post-harvest processing. The study provides quantitative evidence for prioritizing low-emission extraction technologies and precision irrigation management in MAP value chains to maximize both economic and environmental sustainability outcomes.