Genetic variability of agronomic traits and biodiversity in the genus Ocimum

The present study was performed to explore genetic and chemotypic variability among five Ocimum species. Genotypes were evaluated from pooled data over three locations for two consecutive years (2007-2008 and 2008-2009). High genotypic coefficient variation and phenotypic coefficient variation were observed for leaf area (63.55 and 63.80, respectively), essential oil yield (40.37 and 41.0, respectively) and leaf width (33.91 and 39.29, respectively). Maximum heritability estimate in broad sense was observed for leaf area (99.20%), leaf length (98.79%) and essential oil (98.36%). High genetic advance over mean was observed for the essential oil yield (80.59%), leaf width (74.43%), leaf length (69%) and essential oil content (64.71%). In addition, path coefficient analysis showed maximum positive direct effects of plant canopy (4.21), leaf width (3.80), followed by essential oil (2.49%) and fresh herb yield (0.95). The essential oils of Ocimum species were grouped in four chemical groups of compounds. The accessions of O. tenuiflorum, O. basilicum and O. gratissimum were found to be rich with phenylpropanoids. The results clearly showed variation in important economic traits can facilitate selection for further improvement in Ocimum genotypes.