effect of foliar application of ordinary and nano-zinc fertilizers on growth and essential oil profile of dragonhead

In this work, the effects of foliar zinc sprayings on some growth parameters and essential oil composition of dragonhead (dracocephalum moldavica l.) were assessed. a greenhouse experiment was carried out with two sources of zinc including zinc oxide (zno, as ordinary fertilizer) and zinc oxide nanoparticles (zno-np, as nano-fertilizer), each having four concentrations (0, 25, 50, and 100 mg/l). results showed that sprayings with zinc had significant influence on the evaluated parameters. treatments with zno and zno-np significantly increased root length, shoot height, root and shoot dry weights, photosynthesis pigments contents, antioxidant enzymes activity, and essential oil percentage, and in the impact of zno-np was more effective than zno. the highest growth parameters and pigment contents were observed at 100 mg/l zno-np. based on the results, 27 components were identified in the dragonhead essential oil in which the maximum values belonged to oxygenated monoterpenes with four main components as geranial (27.91- 36.09%), geranyl acetate (18.36-25.48%), neral (19.18-21.7%), and geraniol (5.93-8.30%). the amounts of these monoterpenes under zno-np (especially at 100 mg/l) were higher than zno treatment and control plants. the findings of this study showed that the effect of zno-np in increasing the growth, the antioxidant enzymes, and bioactive ingredients of dragonhead was more than zno, and it may be possible to use zno-np as a nano-fertilizer in the sustainable production of essential oil in medicinal plants.