Effects of different locations and controlled greenhouse conditions on morphological, agronomic and chemical characteristics of Mentha arvensis L. and Mentha piperita L. clones and varieties

This study aimed to assess the morphological, agronomic, and chemical properties of Mentha arvensis and Mentha piperita genotypes (clones and cultivars) under controlled greenhouse conditions and at two distinct locations (Isparta and Salihli). Field experiments were carried out during 2021 and 2022 under the ecological conditions of Isparta and Salihli, while greenhouse studies were carried out in a fully automated greenhouse. A total of six genotypes (varieties/clones) were evaluated in the field studies, with the Arven-1 clone of M. arvensis and the Swiss cultivar of M. piperita being used for the controlled greenhouse experiments. The research focused on morphological and agronomic traits, in addition to essential oil content and composition. Essential oils were extracted by distillation and their composition was analyzed using GC-MS. Furthermore, variations in phenolic composition were examined during the controlled greenhouse study As a result of the research, the yield values at the Salihli location were higher than those at the Isparta location. In Isparta, the highest fresh herb and dry leaf yields were obtained from the Swiss cultivar (3400.2 kg/da and 456.7 kg/da, respectively), whereas in Salihli, the highest yields were obtained from the Yakima cultivar (5530.5 kg/da and 765.1 kg/da, respectively). The highest essential oil content was observed in the clone Arven-1 in both locations (Isparta 5.51%, Salihli 6.33%). The main component of the essential oil in the Arven-1 clone was menthol, whereas both menthol and menthone were the main components in M. piperita clones and cultivars. The study revealed that the Arven-1 clone had the highest essential oil and menthol content, while the menthone content was high in Multimentha cultivar at both locations. Under controlled conditions, the highest menthol content in Arven-1 clone was achieved at a temperature of 29/26°C and 400 ppm CO2 with a value of 82.45%. Rosmarinic acid yield reached the highest level at 26/16°C (5.42 µg/mg) in Arven-1 clone and at 29/26°C and 1000 ppm (33.71 µg/mg) in Swiss variety. The study concluded that the Salihli ecology is more favorable for menthol production, especially for the menthol-rich M. arvensis clone (Arven-1), and that climatic conditions influence plant growth and essential oil content.