Development, essential oil yield and composition of mint species and chemotypes under different radiation and nitrogen levels

Resumo

Radiation and soil nutrient levels affect essential oil production in aromatic plants. The objective of this work was to evaluate the vegetative development, essential oil yield and composition of Mentha aquatica L. (linalool chemotype) and Mentha x piperita L. (linalool and menthol chemotypes) cultivated under different radiation levels (100%, 46% and 23%), and with or without nitrogen fertilization. The essential oil samples were obtained from leaves by 3 hours hydro-distillation and analyzed by GC/MS. Reduced leaf area, stem number and total dry mass accumulation was found in all genetic materials submitted to the lowest level of radiation. Nitrogen requirements were different in mint chemotypes, being M. x piperita, linalool chemotype, the only genetic material where nitrogen fertilization resulted in higher stem number and total dry mass under full radiation. Although reduction in radiation levels decreased essential oil yield and the percentage of its major constituents menthol, menthone, linalool and linalil acetate, no correlation between essential oil production and plant development was observed.