Harvest management in rose-scented geranium (pelargonium sp.) for higher essential oil yield and superior quality under semi-arid tropics

Abstract

Rose-scented geranium (Pelargonium species) is grown as a perennial crop for production of high value essential oil, which finds application particularly in high-grade perfumery, cosmetic products and aromatherapy. A field investigation was carried out during 2001-02 to study the harvest of shoots of the crop on attainment of 4, 6 or 8 fully expanded leaves (FEL) and its effect on essential oil yield and quality under semi-arid tropics. Harvesting of shoots with 4 FEL produced 6 harvests / annum against 4 and 3 harvests per annum in the treatments representing harvest of shoots with 6 and 8 FEL, respectively. Highest biomass yield (18.1 t ha−1 annum−1) among the treatments was, however, observed in the treatment 8 FEL. On the contrary, essential oil content in the biomass of treatment of 4 FEL was 27.3 and 55.5% higher than 6 FEL and 8 FEL treatments, respectively. Similarly, estimated essential oil yield in the treatment of 4 FEL was 17.4 and 30.7% higher than 6 FEL and 8 FEL treatments, respectively. Furthermore, the essential oil produced in the 4 FEL treatment was found to contain higher citronellol, geraniol, citronellyl formate, cis- and trans-rose oxides and 10 epi-γ-eudesmol and lower linalool, menthone and isomenthone, than other harvest treatments. The gross and net returns were also remarkably higher in the 4 FEL treatment beside benefit-cost ratio. It is suggested that rose-scented geranium can be harvested more frequently (six harvests per annum) on attainment of shoots with 4 fully expanded leaves in order to produce higher essential oil yield with superior quality and higher return.