Chemotypic characterization and development of morphological markers in Ocimum basilicum L. germplasm

Abstract

Significant variations are observed in the content and composition of the essential oils obtained from different Ocimum species based on their distinct morphological characters and harvesting seasons. Various germplasms of Ocimum basilicum grown in India were compared for the essential oil content and composition to identify the superior germplasm rich in desirable chemical components, such as methyl chavicol and eugenol, that could be exploited for commercial cultivation in western plains of India. The essential oils were extracted using hydro distillation and chemically characterized on Gas Chromatograph–mass spectrophotometer (GC–MS). Colour of the leaves varied from green to purple-green with bunchy, individual and intermediate type of panicles. Maximum oil per cent in leaf was observed in DOB-1 (0.70%), followed by DOB-5 (0.61%) at stage II. Leaves harvested at stage II gave higher essential oil yield than harvested at stage I. The content of methyl chavicol increased at full flowering (stage II), while content of Eugenol and methyl eugenol increased at onset of flowering (stage I). Majority of the germplasm were found to be rich in methyl chavicol, except DOB-4 which was rich in methyl cinnamate. The intensity of purple leaf colour was observed to be positively correlated in lines rich in methyl chavicol. Maximum methyl cinnamate (DOB-4) content, leaf size and average minimum plant height were found positively relationship. Such relationship has become a key factor field nose needs to be properly understood and superior lines DOB-1 and DOB-5 further used in improvement programme.