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Contamination of medicinal plants with heavy metals as Pb and Cd can affect the growth and the essential oil production of the plants and represent a risk to those who consume as medicine. This study aimed to evaluate the effects of absorption and localization of Pb and Cd on growth, ultrastructural aspects of leaves and essential oil yield and composition of Mentha arvensis, applied on the soil with increasing concentrations (8, 16, 32, 64 and 128mg kg-1). There was a differential absorption of Pb and Cd by M. arvensis mainly concentrated in the roots. Pb was found in small amounts in the leaves while Cd largely exceeded the safety limit without symptoms of toxicity. The ultrastructural analysis revealed the metal accumulation on vesicles surrounding the mitochondria and the presence of electron dense deposits surrounding the mitochondria, nucleus and chloroplasts. Little changes caused by Pb and Cd application were not enough to affect the growth and essential oil yield and composition of M. arvensis. [ABSTRACT FROM AUTHOR]

The objective of this research was to verify the influence of different age and types of cuttings in the production of scion of Mentha arvensis L. Four different types of cuttings were evaluated: apical and medium cuttings (from aerial part); tip and medium cuttings (from rhizome part). The different types of cuttings were evaluated at 25 and 40 days of age. The cuttings used had 4-5cm long and covered with Plantmax® substrate to a depth of 2/3. Two rooting periods (25 and 40 days) from the different types of cuttings were evaluated: height, shoots number, aerial and roots dry biomass and percentage of mortality. The cuttings after the rooting period were transplanted to bed and pots. The mortality and the aerial part, roots and rhizome dry biomass were determined 30 days after being cultivated. The results showed that apical cuttings from aerial part at 25 and 40 days after being planted in trays had higher rooting, aerial part development and low mortality. At 25 days the aerial part developed and the scion was ready to be transplanted to field. Thirty days after transplanted apical cuttings from aerial part showed a higher growth, except for rhizome dry biomass. [ABSTRACT FROM AUTHOR]