Effects of Humic Acid and Mycorrhizal Fungus on Some Morphological and Physiological Characteristics of Gerbera Jamesonii ‘Dune’

In order to investigate the effects of humic acid and mycorrhiza on gerbera cv. Dune, an experiment was performed as a completely randomized design with two factors and three replications in hydroponic conditions. First factor included humic acid at 4 concentrations (0, 500, 1000, and 2000 mg L-1 as media drench). The second factor contained two levels of mycorrhizal fungi (with and without mycorrhiza at root zone). Attributes such as leaf number, rosette diameter, root fresh and dry weight, flower diameter, flower stalk diameter and number, time from bud emergence to anthesis, total phenol content, colonization percent and the activity of ascorbate peroxidase and hydrogen peroxide were measured. The results showed that humic acid and mycorrhizal fungi treatments led to increase in the leaf number, rosette diameter, fresh and dry weight of roots and antioxidant enzymes activity and decreased the time from bud emergence to anthesis comparing untreated plants. Phenol content was significantly increased compared to control plants by application of 1000 and 2000 mg L-1 of humic acid plus mycorrhizal fungi. The combined use of humic acid and mycorrhiza was effective to improve some morphological and physiological properties of gerbera and the concentration of 1000 mg L-1 humic acid plus mycorrhiza application were the most effective treatment.