Effect of foliar application of zinc, iron and manganese on morphological and phytochemical traits of hyssop (Hyssopus officinalis L.)

To investigate the effect of iron, zinc, and manganese on morphological and phytochemical traits of hyssop, an experiment was conducted as a randomized complete block design with three replications in 2016. Treatments consisted of control, foliar application of iron, zinc, manganese, iron + zinc, iron + manganese, zinc + manganese and iron + zinc + manganese. The foliar application had a significant effect on all studied traits. Foliar application, especially in combined treatments of the above-mentioned microelements, had a positive effect on all studied traits compared with control. The highest values of plant height (49.55 cm) and biological yield (5085.7 kg/ha) were gained with foliar application of iron + zinc + manganese. The untreated control produced the lowest plant height, number of lateral branch per plant, number of flowering branches per plant and biological yield. The foliar application significantly increased the number of flowering branches per plant and biological yield compared with control. The highest total chlorophyll (1.85 mg g-1 FW) was gained by foliar application of Fe. In addition, foliar application with the combination of microelements produced the greatest total flavonoids content in plants. Results showed that simultaneous foliar application of Fe, Zn and Mn had a positive effect on the quantitative and qualitative traits of hyssop. Therefore, micronutrients could be applied as a suitable strategy to reduce chemical inputs toward sustainable agriculture and to achieve optimum biological yield in hyssop.