Effect of osmopriming and zinc foliar spraying on yield components and mucilage of ‎flower in Marshmallow (Althaea officinalis L.) medicinal plant

The marshmallow is used in Iranian traditional medicine and the pharmaceutical industry for various ailments, including digestive problems, skin irritation and coughs. Zinc plays an important role in the metabolic activities of plants and can affect the quantity and quality of medicinal plants. Osmopriming of seeds could be helping to increase germination, coming out of the soil, establishment, and growth of plants in the field conditions. The experiment was carried out as factorial based on a randomized complete blocks design. The first factor was  seed osmopriming with polyethylene glycol 6000 at four levels (control, -3, -6 and -9 bar) and the second factor was zinc foliar spraying from zinc sulfate source at four levels (0, 1, 2 and 3 g. l-1). Osmopriming on dry weight of the flowers and mucilage yield and zinc foliar spraying on dry weight of flower, number of seeds per fruit and mucilage yield had a significant effect. Treatments had no significant effect on 1000-seed weight. The interaction of osmopriming and zinc foliar spraying in the traits of the number of flowers and fruits per plant, dry weight of fruit, seed yield and mucilage percentage was significant. Foliar spraying 2 g.l-1 of zinc increased the mucilage yield and the flower dry weight, 46% and 57% compared to the control, respectively. The highest mucilage percentage was obtained from control treatments. Generally, the highest yield of flowers and mucilage was obtained from the middle levels of treatments (2 g. l-1 zinc sulfate and -6 bar osmopriming).