EFFECT OF SEASONAL CLIMATIC CHANGES ON BIOMASS YIELD AND TERPENOID COMPOSITION OF ROSE-SCENTED GERANIUM (PELARGONIUM SPECIES)

Variations in biomass yield, essential oil yield and terpenoid composi tion in rose-scented geranium (Pelargonium species) in response to sea sonal climatic changes were investigated under semiarid tropical clima tic conditions A large number of essential oil samples were collected during different seasonal months (once a month) and daily during the p eak summer season months of May and June. They were analysed for terpe noid composition by GC and GCMS. The crop yielded the lowest values fo r biomass yield, essential oil yield and essential oil concentration i n the summer months of April to June. Evaluation of terpenoid composit ions showed minimum concentrations (% of essential oil) of linalool. g eraniol and its esters and maximum concentrations of citronellol and i ts esters during summer months. The percentages of geraniol and its es ters were highest during cool winter season months of December and Jan uary followed by rainy and autumn season months. Isomenthone. 10-epi-g amma-eudesmol and other minor terpenoid compounds (present in <1% amou nts in the essential oil) did not exhibit any definite seasonal trends . Rainy/monsoon (August and September) and autumn (October and Novembe r) season months were characterised by high rainfall, cloudy days and short photoperiods. These favourable environmental conditions encourag ed crop growth and produced highest biomass yields, essential oil yiel ds and maximum concentration of essential oil in rose-scented geranium plants. Copyright (C) 1996 Elsevier Science Ltd