Row Spacing and Harvesting Age Affect Agronomic Characteristics and Essential Oil Yield of Japanese Mint(Mentha arvensis L.)

摘要

A field experiment was conducted to evaluate the influence of row spacing and harvesting age on herb and essential oil yield of Japanese mint (Mentha arvensis L.) at Wondo Genet Agricultural Research Center, EIAR, Southern Ethiopia. The treatments were combinations of four levels of row spacing (30, 40, 50 and 60 cm) and three levels of harvesting age (60, 90 and 120 days after planting). A split plot design with three replications, row spacing as main plot and harvesting age as sub plot was used. Fresh leaf weight, leaf/stem ratio, dry leaf weight, moisture content, fresh biomass weight, essential oil content and yield were recorded. Maximum values for fresh leaf weight, leaf/stem ratio and moisture content were recorded when harvesting was made at60 days after planting. There was a statistically sharp (P < 0.01) increase in essential oil content from 0.5 to 1.4 and to 2% (w/w) with delayed harvesting from 60 to 90 and to 120 days after planting, respectively. A highly significant (P < 0.01) fresh biomass weight reduction was observed when row spacing was widened from 30 to 40 cm by 29.4% from 11,325 kg/ha. The maximum essential oil yield (39.7 kg/ha) was obtained when harvesting was made 120 days after planting at a 30-cm row spacing.