Basil (Ocimum sanctum L.) is an important monoterpene essential oil(s) bearing crop, with the main essential oil constituents being eugenol and linalool. Genotypic and environmental factors play an important role in the growth and physiology of this plant. Genotypic variations have been observed among the six variants with the indigenous one as a control. An efficient genotype OSP-6 of O. sanctum was found to be with higher photosynthetic pigments (1.81 mg g^_1 f.wt.) and 6.94 mg g^_1 (CO₂ ) m^_2 sec^_1 carbon assimilation rate. Maximum essential oil(s) was reported in 4KR (NM) genotype with 1.5% oil formation, whereas 30.44% of the total oil was found in OSP-6 genotype. The maximum peroxidase activity was obtained in OSP-6 genotype with maximum production of biomolecule eugenol. An oxido-reducible reaction of peroxidase and high bands of peroxidase isoenzymes were found in this OSP-6 genotype for the formation of monoterpene essential oil(s) and possibly the major constituents of eugenol through high photosynthates.

Basil (Ocimum sanctum L.), of the family Labiateae is the only source of one of the most important essential monoterpene oil(s) called the oil of French basil or Sweet basil. It is cultivated in many parts of the world for its essential monoterpene oil(s) (Putievsky and Galambosi, 1999). French basil oil is used in perfumery, cosmetics, confectionaries and pharmaceutical industries. From the industrial side, Ocimum species, with oil rich in camphor, citral, geraniol, linalool, linalool acetate, methylchavicol, eugenol, and thymol, are important, and the efficient genotype of French basil, with high value of methyl chavicol, linalool and eugenol, will be studied through physiologically active biochemical changes with end products of photosynthates—the saccharide formation and high value of photosynthetic efficiency as a performance indicator. A crop with seven successions was introduced in controlled condition in Lucknow, northern Indian plains. In this agro-climatic condition, the best efficient genotype of French basil has not been worked out and detailed physiological studies have not been done. Therefore, the study was conducted on the physiologically active growth and its attributes on the biochemical changes and the oil quality and quantity with efficient genotypes of O. sanctum.

Micronutrients, especially Iron (Fe) and Zinc (Zn), act either as metal components of various enzymes or as a functional, structural, or regulatory cofactor, and are thus associated with saccharide metabolism, photosynthesis, and protein synthesis (Marschner, 1986). Zn deficiency reduces plant growth and inhibits photosynthesis in many plants, including forest trees (Dell and Wilson, 1985), fiber crops (Ohki, 1976), rice (Ajay and Rathore, 1995), and spinach (Randall and Bouma, 1973). Zn retards the activity of carbon metabolism enzymes such as carbonic anhydrase (Ohki, 1976 and 1978), ribulose 1,5-bisphosphate carboxylase/oxygenase and fructose-1,6-bisphosphate (Marschner, 1986). Essential oil biosynthesis in basil is strongly influenced by Fe and Zn, and the stress caused by extrinsic and intrinsic factors affect the overall nutrition and growth. Further, micronutrients are involved in carbon and saccharide accumulation, free radical removal, antioxidant enzymes, carbon utilization in terpene biosynthesis, and the overall growth of plants. The requirement of micronutrients for Japanese mint and its limitations imposed on photosynthetic carbon metabolism and translocation in relation to essential oil accumulation in mint were shown by Misra and Sharma (1991), whereas the antioxidant enzyme peroxidase for free radical quenching in the basil has not been fully documented.

Genetics & Evolution Journal, Chlorophyll, Dry Mass, Leaf Area, Net photosynthetic Rate, Plant Height, Saccharides, Genotypes, Photosynthates, Carbonic Anhydrase, Enzyme Peroxidase, Central Institute of Medicinal and Aromatic Plants, CIMAP, Perkin-Elmer Model, Photosynthetic Process, Carbonic Anhydrase Activity.