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Highlights • Pollination in mint, could be considered to expand variation and increase genetic homogenicity for selecting superior plants. • Pollination changed essential oil components including pulegone, carvone, limonene and piperitenone in mint offspring. • Self-pollination significantly increased or decreased the flavonoid content in some populations of mint. Abstract Understanding the reproductive system of mint (Mentha spp.) through self or open pollination is critical for its improvement. In this study, fresh and dry weight, essential oil yield, essential oil composition, flavonoid and phenolic contents of 12 mint populations derived from self and open-pollination, plus their parents belonging to two species, were evaluated. The results showed inbreeding depression in self-pollinated populations compared with the parents, for fresh and dry weights and essential oil yield belonging to Mentha longifolia , but in populations belonging to Mentha spicata , fresh weight, dry weight and essential oil yield increased in self and open-pollinated populations, compared with the parents. The possibility of self-pollination and subsequent improvements in offspring may be considered as an existence of some self-compatibility in mint species. Gas chromatography-mass spectrometry (GC–MS) and GC-FID analyses were also performed to determine the essential oil components. Accordingly, 29 compounds were determined including pulegone (0.87–71%), piperitenone (0.94–76.87%), carvone (0.19–52.01%), and limonene (1.19–26.61%) in the genotypes of M. longifolia and M. spicata. The amount of pulegone, as well as limonene and carvone, significantly decreased in some populations derived from self and open pollination while a significant increase in the amount of piperitenone and menthone was found in this condition. Results also showed that the pollination system had no significant effect on phenolic content while self-pollination significantly increased the flavonoid content of Hamedan and Lorestan populations. Self-pollination in mint may be viewed as a useful way to increase genetic homogenicity for the selection of superior plants in breeding programs for pharmaceutical purposes. [ABSTRACT FROM AUTHOR]

Given the significance spearmint (Mentha spicata L.), there is an increased demand for dry medicines and high-quality aromatic mint. In this study, a non-destructive technique based on electronic nose was used in combination with a GC/MS method and chemometrics to determine the quality of spearmint essential oil under eight drying methods. It was found that hot air drying (HAD) method yielded the highest amount of essential oil and its compounds. So that its highest amount was obtained in HAD1a method and equal to 1.380%. However, the amount decreased with increasing drying temperature and air velocity. In addition, sun drying performed worst its value was equal to 0.663%. The highest percentage of the obtained essential oil compounds was related to the three main components of carvone (64.30–7.45%), limonene (24.21–6.59%), and carveol (18.34–1.92%). Furthermore, the Nu-SVM classification algorithm with the sigmoid function provided an accuracy of 0.975 for classifying eight essential oil groups. In light of the limited knowledge about the effects of drying on the qualitative and quantitative characteristics of medicinal plants, a new method for essential oil evaluation was proposed in this study. The results could provide a theoretical reference to choose the best drying method and quickly determine the quality of mint essential oils. • The HAD1A drying technique displayed the highest essential oil yield, while sun drying showed the lowest, also demonstrates a decrease in essential oil amount with rising drying temperatures and air velocity. • Three classification algorithms were used to evaluate the aromatic properties of mint essential oil. The Nu-SVM method achieved the highest classification rate using the sigmoid function with 0.975. • This study highlights the need for continued research on enhancing drying technology and implementing monitoring systems for sensory quality control. [ABSTRACT FROM AUTHOR]

The systematics of the Mentha genus is very complicated and still unclear. This is mainly due to the existence of variation in basic chromosome number, frequent interspecific hybridization, cytomixis, polymorphism in morphology and essential oil composition under different environmental conditions, colonial mutant propagation, as well as the occurrence of polyploidy, aneuploidy and nothomorphs. Morphological traits, chemical composition, and even caryological analysis failed in discrimination of Mentha species. Therefore, the aim of this study was to combine genome size estimation with ISSR markers for quick and precise species identification, determination the inter- and intraspecific variation within this genus, as well as description of relationships between genotypes. Genome size estimation revealed, that investigated Mentha species possessed very small and small genomes. Additionally, for 13 Mentha species, this is the first report on genome size. Within one species different values of genome size occurred, which indicated polyploidy and aneuploidy. The smallest genome (0.63 pg/2C) was detected in M. gattefossei , while the largest in M.   ×   verticillata (4.15 pg/2C). Flow cytometric measurements of genome size allowed to distinguish some species and cytotypes, and thus it can be used as a first step in species identification. More precise and detailed characterisation were provided by ISSR markers. All the primers used in ISSR-PCR, revealed to be useful in species identification, while primers (GACA) 4 , (GTG) 6 T, (CTC) 4 RC, (GA) 6 CC enabled to distinguish M. aquatica , M. canadensis , M. longifolia , M . pulegium and M . spicata cytotypes, and primers (GACA) 4 , (GA) 6 CC and (GA) 8 YC to identify M.   ×   gracilis and M.   ×   piperita cultivars. The phylogenetic analysis revealed the existence of seven main clusters and two species ( M. requienii and M . ×  smithiana ) being not clustered to any of the created groups within the Mentha genus. This analysis mostly confirms the latest taxonomical classification of the Mentha genus, however some exceptions are discussed. The identification system of combined genome size estimation, and ISSR markers proved to be useful for species in Mentha genus. [ABSTRACT FROM AUTHOR]

The increasing cost of synthetic fertilizers and conventional agrochemicals calls for an urgent search for next generation of environmental-friendly competitive fertilizers and growth stimulants that enhance the essential oil content and composition of traditional global medicinal plants such as mint ( Mentha × piperita L.“chocolate”) and sweet basil ( Ocimum basilicum L. “purple ruffle”). The study aims to evaluate the morphological and physiological effects of seaweed extracts ( Ascophyllum nodosum ) doses and application methods on mint and basil plants essential oil composition and its respective antibacterial activities. The plants were subjected to two doses of foliar/drench weekly applications of A. nodosum extracts at 5 and 7 mL L −1 for 12 weeks. A. nodosum extracts drench and foliar treatments increased leaf number and area, dry weights, and plant height of both plants. In mint and basil plants, there were increases in the essential oil content and enhanced composition following A. nodosum treatments. In mint plants, the drench application of 7 mL L −1 SWE had the highest oil contents of l -menthone (32.4%) and l -menthol (32.6%) while basil treated plants showed the highest composition of chavicol methyl ether (38.7%), linalool (29.1%), and cineol (9.1%). Additionally decreasing of potentially toxic pulegone and methofuran in mint oil was noticed. A. nodosum treated plants showed higher antibacterial potential than control. In mint and basil plants, the highest antibacterial activity found was in the essential oil of mint plants drenched with 7 mL L −1 SWE and the antibacterial activities of mint oils were higher than basil. The biostimulant effect of A. nodosum extract treatments was attributed to the macro- and micro-elements composition as well as the carbohydrate contents. [ABSTRACT FROM AUTHOR]

Highlights: [•] Irradiated sodium alginates (ISA) enhanced plant growth promoting activities. [•] Foliar spray of ISA, TRIA and HBR improved growth, yield and quality of mint. [•] Combined treatment (100ppm ISA+10−6 M TRIA+10−7 M HBR) proved to be the best. [•] Combined treatment gave maximum content (43.9%) and yield (121.7%) of essential oil. [Copyright &y& Elsevier]

Highlights: [•] The methanol extract has strong antioxidant activity. [•] The essential oil has good antimicrobial activity. [•] 37 compounds were identified and carvone being the major compound in the oil. [Copyright &y& Elsevier]

Highlights: [•] Japanese cornmint is a subtropical essential oil crop grown for production of natural crystaline menthol. [•] This study evaluated the effect of harvest dates (HD) in the fall (during the period of fall frosts) on Japanese cornmint. [•] Japanese cornmint withstood the first few fall frosts and provided desirable oil composition. [•] Japanese cornmint could be a viable crop for northern latitude (around 44° N). [ABSTRACT FROM AUTHOR]

[Display omitted] • Iranian mints showed a great diversity in essential oil yield and components. • First essential oil yield report in M. villosa , M. suaveolens , M. rutoundifolia. • Mentha suaveolens had the highest amount of essential oil yield 1.3 % (w/w). • Menthol (53.1 %) was the maximum constituent found in M. piperita. • For the first time carvone (27.12 %) was identified in M. rutoundifolia. Mentha is an important aromatic plant in the Lamiaceae family with a great industrial potential which has a very complex classification. Mint genotypes (Mentha × piperita 'Black', M. × piperita 'White', M. × aquatica , M. × villosa , M. longifolia , M. rutoundifolia , M. suaveolens) were gathered from different regions of Iran to investigate their essential oil (EO) yield and components. Mints were cultivated in the greenhouse and their essential oils were obtained by hydro distillation. EO yield varied from 0.51 to 1.3% (w / w). Gas chromatography analysis revealed that each species consisted of 46–64 constituents which make up about 98.2 %–99.85 % of their essential oils. A total 111 types of chemicals were identified, of which only ten were common between species, which together constitute 0.5 %–3.5 % of the total essential oils. The other 101 components showed a great diversity, of which 29 were major constituents of these genotypes. Principle component analysis (PCA) showed that the type and amount of the constituents are important to determine their groups. Diversity classification based on quantity and quality of EOs, put them into four groups. The highest detected components in the respective mints were: carvone (55.08 %), M. suaveolens ; menthol (53.1 %), M. ×piperita 'Black'; pulegone (44.55 %), M. longifolia ; menthofuran (38.67 %), M.×aquatica ; menthol (32.36 %), M. × piperita L. 'White'; carvone (27.12 %), M. rutoundifolia ; and neo-menthol (22.79 %), M.× villosa. For the first time new constituents were identified: α-terpinyl acetate (5.03 %) and geranyl tiglate (10.81 %) were found in M. longifolia ; carvone (27.12 %) was identified in M. rutoundifolia ; and neo-menthol (22.79 %) and pulegone (10.90 %) were detected in M. villosa. The phytochemicals demonstrate a great diversity among the studied Iranian mint species. These results merit further investigations at the gene expression and proteomics levels. [ABSTRACT FROM AUTHOR]