Agronomic Characters, Leaf and Essential Oil Yield of Peppermint (Mentha piperiata L.) as Influenced by Harvesting Age and Row Spacing

摘要

An experiment was conducted with the objective of quantifying the effect of harvesting age and spacing on agronomic and chemical characters of peppermint (Mentha piperiata L.) during 2009/2010. Five levels of harvesting ages and four levels of spacingwere assigned to sub-plots and main plots, respectively in a split plot design with three replications. Data on fresh leaf yield, dry leaf yield, fresh above-ground biomass yield, dry above-ground biomass yield, fresh leaf/stem ratio, dry leaf/stem ratio, essential oil (EO) content and EO yield were collected and analyzed for the first and second harvests. For both harvests, harvesting age exerted a highly significant influence (P < 0.01) on all parameters studied. Row spacing significantly influencedall the parameters except for fresh leaf/stem ratio, dry leaf/stem ratio and EO content during the first harvest. During the second harvest, row spacing affected fresh leaf yield, fresh above-ground biomass yield, dry above-ground biomass yield, fresh leaf/stem ratio significantly (P < 0.05) and dry leaf and EO yield highly significantly (P < 0.01). The interaction effect of row spacing and harvesting age exerted a significant influence (P < 0,05) on dry leaf and EO yield during the second harvest. Fresh leaf and EO yield varied from 3,650.9-10,882.1 and 10.2-18.8 kg/ha, respectively and maximum values were obtained at the harvesting age of 120 days after planting at first harvest. Maximum yield of 9,967.5 kg/ha fresh leaf and 17.88 kg/ha EO was obtained with a 30-cm row spacing.