Mint species are economically important for their essential oils, and their growth and chemical profiles are sensitive to various stressors.

*   **Abiotic Stress Factors:** Mint is affected by a wide range of abiotic stresses including salinity, drought, heat, and heavy metals.
*   **General Effects:** These stressors alter the plant's morphology, physiology, and biochemical processes, leading to dysfunction in growth, photosynthesis, and respiration.
*   **Drought Stress:** Decreases fresh and dry weight, leaf number, plant height, and root dry weight.
*   **Drought and Essential Oils:** While biomass may decrease, drought stress can sometimes increase the concentration of essential oils and enhance their antioxidant activity.
*   **Drought and Photosynthesis:** Water stress negatively impacts photosynthetic activity.
*   **Salt Stress:** High salinity levels adversely affect plant growth, oil yield, and physiological parameters.
*   **Salinity and Biomass:** Increasing NaCl concentrations significantly reduces fresh and dry biomass production.
*   **Salinity and Essential Oils:** Moderate salinity may increase essential oil content, but higher levels cause a decrease. Salinity also alters the chemical composition of the oil, decreasing menthol while increasing menthone and menthofuran.
*   **Proline Accumulation:** The amino acid proline increases in tissues under environmental stress, indicating an adaptive response.
*   **Chlorophyll Content:** Drought stress can cause a reduction in chlorophyll content.
*   **Phenolic and Flavonoid Content:** Drought stress has been shown to increase total phenolic and flavonoid content.
*   **Oxidative Stress:** Drought can lead to an increase in hydrogen peroxide and malondialdehyde (MDA) content, indicating oxidative stress.
*   **Species Sensitivity:** Among different mint species, *Mentha arvensis* is particularly susceptible to loss of oil percentage under salinity stress.
*   **Heat Stress:** Reduces the content of essential oils.
*   **Combined Stresses:** The response of mint to combined stresses can differ significantly from its response to a single stress factor.
*   **Phytohormones:** The application of various phytohormones can help alleviate the negative impacts of environmental stress.
*   **Bio-stimulants:** The use of commercial bio-stimulants can improve morphological performance and ameliorate the effects of water stress.
*   **Root Formation:** Salinity stress can inhibit adventitious root formation, which is important for vegetative propagation.
*   **Secondary Metabolites:** The production of secondary metabolites is a defense mechanism for survival and adaptation to stress conditions.