Effects of different humic acid levels and planting density on antioxidant activities and active ingredients of saffron (Crocus sativus L.)

The effects of applications of humic acid and planting density on antioxidant activities and components of saffron were evaluated under field conditions. Treatments were of four levels of humic acid (0, 5, 10 and 15 Kg.ha-1) and three densities of planting (50, 75 and 100 corms.m-2). The experiment was designed in randomized block design with three replications at the research station of the Faculty of Agriculture at the University of Birjand during the growing season of 2015. Petal antioxidant compounds (antioxidan, total phenol and Anthocyanins) and active ingredients of saffron (picrocin, safranal and crocin) were influenced by humic acid and planting density treatments. The highest antioxidant activity (69.7%) was obtained in plants treated with 5 kg.ha-1 humic acid with a planting density of 50 corms.m-2. However, no significant difference was found in phenol content under different treatments. The highest anthocyanin content (46.4 mg.100 g-1) was observed in 10 kg.ha-1 humic acid with a planting density of 75 corms.m-2. Picrocin content was influenced in response to humic acid planting density and the highest value (40.60%) was obtained from 15 kg.ha-1 humic acid with a planting density of 75 corms.m-2. The highest safranal (20.1%) and crocin (55.57%) were obtained in plants treated with10 kg.ha-1 acid humic, while the lowest values were recorded in the control (15.70%) and (43.12%) respectively. Thus, the results showed that humic acid and planting density have strong impacts on antioxidant compounds and active ingredients of saffron under field conditions.