Field marker character for essential oil content in green herbage through leaf colour intensity in holy basil (Ocimum sanctum L.)

Six accessions of holy basil (Rama and Shyama) obtained from different parts of India were evaluated for morphological and quantitative parameters. These accessions were observed for leaf colour, trichome type, number and size of peltate gland (PG), stem girth, branches and other agronomical parameters. Besides that, they were also observed for yield contributing characters viz., maximum plant height, spread, stem girth, fresh leaf, dry leaf, herbage yield and essential oil yield. DOS-22 was found superior for larger leaf, herbage and essential oil yield. Maximum number of peltate glands (PG) on abaxial leaf surface as compared to adaxial were recorded. However, PGs formation takes place only in younger leaves, therefore, the numbers of PGs were reduced due to expansion of leaf area with progression of age. Purple leaf colour intensity and essential oil content in herbage had negative relationship with each other, therefore, the green colored accessions (DOS-1, DOS-19 and DOS-22) are rich in essential oil content in herbage. Therefore, green and purple colour intensity in leaf is to be field marker character for initial screening of accessions for essential oil content.