Traditional knowledge and field marker development for essential oil content using peltate gland trichome and leaf colour in basil (Ocimum basilicum L.)

Abstract

Twenty-six accessions of sweet basil obtained from different parts of India were evaluated for morphological and quantitative characters. These accessions were observed for distinguish characters like trichome type, peltate gland (PG) size, sepal and flower colour, stem girth, branching pattern, growth habits and leaf colour. Besides that, they were observed for yield contributing characters viz., maximum plant height, spread, stem girth, fresh leaf, dry leaf, herbage yield and essential oil yield, and DOB-8W was found superior as compared to checks. Maximum number of peltate glands (PG) on abaxial leaf surface as compare to adaxial were recorded at all the three stages (young, mature and old based on leaf position on axis). However, PGs formation takes place only in younger leaves, therefore, the numbers of PGs were reduced in mature and older leaves due to expansion of leaf area with progression of age. Number of PGs on abaxial surface of young leaf, green leaf colour and essential oil content had positive relationship with each other. The green and purple colour intensity in leaf is to be field notch for initial screening of accessions for essential oil content.