Abstract
We investigated the changes in the amount and composition of essential oil in the leaf blades and sheaths during the growth of two different strains of lemongrass (citral-dominant strain and geraniol-rich strain). Lemongrass plants were grown in pots, and the aerial parts of the plants (leaf blades and sheaths) were harvested at 15, 30, 45, and 60 days after the first fertilizer application. The leaf essential oil was extracted and purified by a solvent-based method that we newly developed for lemongrass leaves. The two strains of lemongrass grew with similar patterns during the experimental period, and the aboveground biomass increased exponentially after 30 days. In both lemongrass strains, the concentration of essential oil in the whole leaves decreased with growth as a result of a significant decrease in the leaf blades, whereas the amount of essential oil per hill increased rapidly with increasing aboveground biomass. These results indicated that the yield of essential oil per hill depended mainly on the biomass of the aerial parts, regardless of lemongrass strains. We also found that there were significant differences in the composition of the essential oil in the leaf blades and in the sheaths, and that the proportion of the constituents appeared to vary during the experimental period, particularly in the geraniol-rich strain of lemongrass. These results suggest that the ability of lemongrass leaves to synthesize and accumulate essential oil constituents varies depending not only on the strains of lemongrass, but also on the part of the leaf and the developmental stage of the plant.
