The Effect of Foliar Application of Zinc on Essential Oil Content and Composition of Holy Basil [Ocimum sanctum] at First and Second Harvests

Holy basil is a perennial plant belongs to lamiaceae family. In order to evaluate the effect of foliar application of zinc on essential oil content and composition of holy basil, an experiment was conducted at research farm, based on randomized complete block design with six treatments and three replications. The treatments were nano zinc chelate (0, 0.5, 1 and 1.5 g/l) and zinc sulfate (1 and 1.5 g/l) fertilizers. Zinc content, glandular trichomes number, glandular trichomes size, essential oil content, yield and composition were measured at full bloom stage. The results showed that the effect of foliar application of zinc fertilizers on all measured traits were significant (p0.01). The highest and lowest values of zinc and essential oil content were obtained in plants sprayed with 1.5 g/l nano zinc chelate and control, respectively. Moreover, eugenol, 1,8-cineole and methyl chavicol were the most oil components of all treatments at both harvests. Other main compounds of essential oil were ocimene, bisabolol and alpha-bisabolene. Overall, there were no significant differences between 1 and 1.5 g/l nano zinc chelate and 1.5 g/l zinc sulfate treatments for essential oil content and yield of holy basil. Therefore, foliar application of 1.5 g/l zinc sulfate is recommended.