1- University of Mohaghegh Ardabili
2- University of Lorestan
2- University of Lorestan
Abstract: (4 Views)
Background: The study of wild plant species to enhance the performance of crops is highly significant. The first step in the improvement of medicinal plants is the identification and collection of native genotypes due to their adaptation to the climate of the target region. The aerial parts of peppermint (Mentha piperita L.), which contain essential oils, phenolic compounds, flavonoids, fatty acids, vitamins, minerals, and salicylic acid, play a crucial role in selecting cultivars. In most medicinal plant production methods, quick access to equipment for extracting active ingredients, particularly on a large scale, is not feasible without drying, which constitutes a significant portion of post-harvest operations. The quality of the dried medicinal plant depends on its active compound content, allowing for later extraction of effective materials. Menthol, the primary component of peppermint oil, is synthesized in trichomes on the leaf surface and accumulates there. Peppermint, as one of the most important medicinal plants in the Lamiaceae family, produces a diverse group of secondary metabolites. Medicinal plants are known for their spasmolytic, anti-diarrheal, antioxidant, sedative, and antimicrobial properties. In addition to their therapeutic effects, they are used as flavoring agents in food production and pharmaceutical products. The fundamental need for plant breeding programs is the diversity of germplasm, which facilitates the selection of desirable traits for improvement. Accurate identification of genotypes is essential for success in such methods.
Methods: The study was conducted to examine the diversity of essential oil content and chemical composition under different drying methods. Using a randomized complete block design with three replications, the research was performed at the Agricultural and Natural Resources Research Station in (Meshgin shahr) Ardabil Province, Iran, in 2022. Six peppermint accessions from various regions of Iran (Ardabil, Hamadan, Kurdistan, Golestan, Meshgin, and Firoozabad) were cultivated. After sowing, irrigation was done immediately. Agricultural operations during the growing season, including hand-weeding and pest and disease control, were performed. The effect of two drying methods (shade drying and oven drying at 40°C) on essential oil yield was investigated. Peppermint plants were harvested at full flowering, and the aerial parts were dried either in the shade or in an oven for essential oil extraction. Essential oils were extracted using the Clevenger apparatus via hydro-distillation under uniform conditions. Gas chromatography–mass spectrometry (GC-MS) was used for chemical analysis, and statistical data analysis was performed using SPSS software.
Results: Peppermint has historically been used as both a medicinal and aromatic plant. Its volatile oils are among the most important essential oils with strong antimicrobial activity. The appropriate harvesting time for the plant should be determined to maximize effective compounds and dry matter yield.. Variance analysis results showed significant differences in essential oil yield among peppermint accessions at 1% and 5% probability levels and in three-way interactions. Additionally, mean comparison results indicated that plants from the Ardabil accession, dried in the shade at full flowering, had the highest essential oil yield. Correlation results revealed the strongest relationship between Cyclobenzene and Isoaromadendrene (r = 0.98). Menthol (32.32%) was identified as the most abundant compound, followed by Pulegone (28.21%), Calyptol (12.50%), and Caryophyllene (8.12%).
Conclusion: Preserving plant biodiversity is crucial for creating structural diversity and primary compounds for sustainable development in the future. Medicinal plants have been a rich source of essential compounds for treating various diseases since ancient times and hold a special place in research. The findings of this study indicate significant genetic diversity among peppermint accessions in Iran, providing potential for genetic comparison and cultivar development. Plants from the Ardabil accession at full flowering, dried in the shade, demonstrated the highest essential oil yield and number of compounds, with menthol being the predominant compound (32.32%). The Kurdistan accession showed the second-highest menthol content. These results suggest the possibility of selecting desirable accessions and identifying superior traits for future breeding programs.
Methods: The study was conducted to examine the diversity of essential oil content and chemical composition under different drying methods. Using a randomized complete block design with three replications, the research was performed at the Agricultural and Natural Resources Research Station in (Meshgin shahr) Ardabil Province, Iran, in 2022. Six peppermint accessions from various regions of Iran (Ardabil, Hamadan, Kurdistan, Golestan, Meshgin, and Firoozabad) were cultivated. After sowing, irrigation was done immediately. Agricultural operations during the growing season, including hand-weeding and pest and disease control, were performed. The effect of two drying methods (shade drying and oven drying at 40°C) on essential oil yield was investigated. Peppermint plants were harvested at full flowering, and the aerial parts were dried either in the shade or in an oven for essential oil extraction. Essential oils were extracted using the Clevenger apparatus via hydro-distillation under uniform conditions. Gas chromatography–mass spectrometry (GC-MS) was used for chemical analysis, and statistical data analysis was performed using SPSS software.
Results: Peppermint has historically been used as both a medicinal and aromatic plant. Its volatile oils are among the most important essential oils with strong antimicrobial activity. The appropriate harvesting time for the plant should be determined to maximize effective compounds and dry matter yield.. Variance analysis results showed significant differences in essential oil yield among peppermint accessions at 1% and 5% probability levels and in three-way interactions. Additionally, mean comparison results indicated that plants from the Ardabil accession, dried in the shade at full flowering, had the highest essential oil yield. Correlation results revealed the strongest relationship between Cyclobenzene and Isoaromadendrene (r = 0.98). Menthol (32.32%) was identified as the most abundant compound, followed by Pulegone (28.21%), Calyptol (12.50%), and Caryophyllene (8.12%).
Conclusion: Preserving plant biodiversity is crucial for creating structural diversity and primary compounds for sustainable development in the future. Medicinal plants have been a rich source of essential compounds for treating various diseases since ancient times and hold a special place in research. The findings of this study indicate significant genetic diversity among peppermint accessions in Iran, providing potential for genetic comparison and cultivar development. Plants from the Ardabil accession at full flowering, dried in the shade, demonstrated the highest essential oil yield and number of compounds, with menthol being the predominant compound (32.32%). The Kurdistan accession showed the second-highest menthol content. These results suggest the possibility of selecting desirable accessions and identifying superior traits for future breeding programs.
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