Response of Mentha spicata L. to the reclamation of soil by the application of polyacrylamide (PAM): A soil‐conditioner

Abstract

Polyacrylamide (PAM) is effective in stabilizing aggregation and erosion of the soil which may lead to an improvement in growth and yield of plants like Mentha. Mentha spicata L. is an important aromatic and medicinal plant, valued economically for the plant oil. It finds its application in pharmaceutics, pharmacology, cosmetics, and others, which necessitate the escalated production of this plant. Therefore, the present study was designed with the treatments; soil-applied de-ionized water (control) and soil-applied PAM (40, 80, 120, and 160 mg/kg of soil). The plant analysis was carried out at 150 days after planting (DAP). The treatment of PAM-120 was significant (p ≤ .05) as a soil conditioner in improving the growth, photosynthetic, and yield-related attributes of the plant. An increase of 35.2% and 41.8% was reported in fresh and dry weights of the plant while total chlorophyll and carotenoids and chlorophyll fluorescence increased by 20.2%, 12.3%, and 9.6%, respectively, at 150 DAP. Essential oil (EO) content was increased by 20.5% and EO yield by 59.8%. However, peltate glandular trichomes density and diameter was improved but was statistically insignificant over the control. Conclusively, PAM-120 proved best in enhancing the performance of the crop, including EO production of spearmint possibly due to the enhanced nutrient uptake and soil water-retention capacity. Novelty impact statement The study unravels the augmentation of essential oil of spearmint as a result of soil-dressing with polyacrylamide, the ecofriendly soil conditioner. The current study, which might be claimed as a first report in the scientific literature regarding the effect of PAM on spearmint, reports an increase of essential oil content and yield by 20.5% and 59.8%, respectively, over the control.