Produ？？o de biomassa e teor de óleo essencial em fun？？o da idade e época de colheita em plantas de hortel？-japonesa

this present work aimed to evaluate the effect of period and age the plants on harvest, dry biomass production, essential oil percentage content and storage period of mint (mentha arvensis l.) plants. two experiments were set: the first evaluated the effect of three harvest ages (80, 100 and 120 days) after transplanting, and three ages at the second harvest (60, 75 and 90 days). a randomized blocks design was used, with four replications in a 3 x 3 factorial scheme. in the second experiment, three harvest periods were evaluated - early january, late march and early june. the harvested material was dried at 37°c, the dry biomass of the aerial parts was calculated, the essential oil was extracted in a modified clevenger instrument and its percentage contents were calculated. plant age at first harvest did influence essential oil content and dry biomass of the aerial parts in response to plant age at the second harvest. the harvest period in which the essential oil content was higher was in early june.