Low iron stress nutrition for evaluation of Fe-efficient genotype physiology, photosynthesis, and essential monoterpene oil(s) yield of Ocimum sanctum

Genotypic variations were observed among 6 variants and an indigenous one as a control. An efficient genotype OCD(L) of Ocimum sanctum had the greatest content of chlorophylls [2.15 g kg⁻¹(FM)], Chl a/b ratio of 1.86, net photosynthetic rate of 0.72 mg(CO₂) m⁻² s⁻¹, and 1.56 % oil formation. Methyl chavicol formed 50.31 % of total oil in OSP-6 genotype, which had also maximum peroxidase activity [ΔOD 2.4 mg⁻¹(protein)] and maximum production of eugenol (30.44 % of total oil). We found an oxido-reducible reaction of peroxidase and high bands of peroxidase isoenzymes in this OSP-6 genotype for the formation of monoterpene essential oil(s) and possibly the major constituents of eugenol through the high production of photosynthates.