Role of organic and inorganic fertilizers in enhancing biomass yield and eugenol content of ornamental basil (Ocimum gratissimum L.)

Ornamental basil is an important essential oil yielding species in the Lamiaceae family is an extensive source of eugenol content and exhibits potential pharmacological properties. In the present scenario the environment conditions are constantly changing thus present study was under taken to study the influence of different growing condition, open and natural ventilated polyhouse, and organic and inorganic fertilizers and their interactive effect to optimise the best environment for higher biomass and improved essential oil quality under high rainfall conditions of South Gujarat, India. The eugenol content in leaf essential oil was characterized using Gas Chromatography – Flame Ionization Detection (GC-FID). The results showed that plants grown under polyhouse conditions had higher growth rates and biomass yields than those grown in open conditions due to the change in microclimatic conditions. Among the different growing environments, plant height (12.98%), number of branches (67.73%), number of leaves (131.49%), leaf area (151.09%), fresh biomass (131.90%), dry biomass (108.27%), leaf essential oil yield (206.09%) and eugenol (20.95%) per plant higher in comparison to open condition. Similarly, the 25% NPK and 75% N through vermicompost (F5) showed significantly better results in number of branches (6.25), number of leaves (135.30), leaf area (2936.49 cm2), total fresh biomass (89.71 g), dry biomass (17.76 g) and leaf essential oil yield (0.189 g) per plant. The interactive effect of growing conditions and fertilizer treatments reported that maximum plant height (85.15 cm), number of branches per plant (7.73), number of leaves per plant (191.07), leaf area per plant (4455.77 cm2), total fresh biomass per plant (124.92 g), total dry biomass per plant (23.93 g), leaf essential oil yield per plant (0.284 g) and eugenol content (54.117%) was observed in plants under polyhouse conditions treated with 25% NPK + 75% N through vermicompost, respectively. Thus, the results from the present study provides significant insights towards the best growth condition and fertilizer dosage for optimising the package of practices for better growth, yield and essential oil quality in ornamental basil for the farmers to meet the demands of market.