The micronutrient zinc (Zn) plays an important essentialrole in various physiological processes of plants. In this research, the acclimatized samples of valerian (Valeriana officinalis L.), chicory(Cichorium intybus L.), withaniaWithania (Withania. coagulans), and purple coneflower (Echinacea purpurea L.) were studiedunder aeroponicsystem conditionsandto explorethe effects of zinc oxide nanoparticles (ZnO NPs) were investigated. The plants were foliar sprayed with ZnO NP biofertilizer (0, 1, 2, and 3 g l-1) at 20, 40, and 60 days after transplanting. The experiments were carried out according to a completely randomized design (CRD) layout with five replications. The results showed significant differences amongbetween thetreatmentsfor all measured traits of three studied plant species.whereas theThe highest magnitudes of photosynthetic pigments, carotenoid, plant height, root length, root volume, leaf number per plant, root fresh weight, root dry weight, shoot fresh weight, and shoot dry weight were obtained at3 g l-1 ZnO NPs treatment. It was found thatTheapplication of ZnO NP application in the aeroponic system increased enhancedthe biomass of chicory, withaniaWithania, valerian, and purple coneflower plants. Therefore,and so, Zn is an essential micronutrient for in the growth ofthese plants growth and should be prepared as well as possiblyeespecially in nano-sized form.
