The consequence of genotype × environment interaction on high essential oil yield and its composition in clove basil (Ocimum gratissimum L.)

Clove basil (Ocimum gratissimum L.) is an aromatic, perennial herb belonging to the family Lamiaceae. The plant is indigenous to tropical areas especially India and West Africa. In Nigeria, it is found in the Savannah and coastal areas. The whole herbs of the plant contain essential oils and it is cultivated for various purposes. The plant is a rich source of eugenol in its essential oil. It is also used in the preparation of tea and infusions. It is also used in the treatment of fungal infections, fever, cold, and cough. Eugenol (4-allyl-2-methoxy phenol) is a phenolic compound from the class of phenylpropanoids. It is used in the food industry as a preservative, mainly due to its antioxidant property, and flavoring agent. The fresh herb × winter season/environment produced the highest essential oil 2.07 mL/plot with essential oil content 0.41% followed by fresh herb × summer season/environment (M1S2) = 1.68 mL. For the eugenol content, the autumn season/environment was found highly favorable = 74.52% (leaves = 69.024, stem = 74.531, and in inflorescence = 80.012) followed winter season/environment 72.30% (leaves = 71.841, stem 69.389, inflorescence 76.042, mean = 72.42%). These seasons are recommended for harvesting to obtain the optimum benefit for the quality essential oil yield.