Changes in the essential oil content and its composition during palmarosa (Cymbopogon martinii (Roxb.) Wats. var. motia) inflorescence development

The flowering tops of palmarosa (Cymbopogon martinii) consist of spikelets and each spikelet is further composed of racemes and a leaf-like structure called a spathe. Both racemes and spathe contain essential oil. Changes in fresh weight, dry weight, chlorophyll and essential oil content and its maj or constituents, viz. geraniol and geranyl acetate, were examined for both racemes and spathe at various stages of spikelet development. The essential oil content was maximal at the unopened spikelets stage and decreased sign ificantly thereafter. At unopened spikelets stage, the proportion of gerany l acetate (58.6%) in the raceme oil was relatively greater compared with ge raniol (37.2%), whereas the spathe oil contained more geraniol (61.9%) comp ared with geranyl acetate (33.4%). The relative percentage of geranyl aceta te in both the oils, however, decreased significantly with development and this is accompanied by a corresponding increase in the percentage of gerani ol. Analysis of the volatile constituents from racemes and spathes (from ma ture spikelets) and seeds by capillary GC indicated 28 minor constituents b esides the major constituent geraniol. (E)-Nerolidol was detected for the f irst Lime in an essential oil from this species. The geraniol content predo minated in the seed oil, whereas the geranyl acetate content was higher in the raceme oil. Copyright (C) 2000 John Wiley & Sons, Ltd.