The Effect of Micronutrients Supplementation (Fe, Zn, B, and Mn) on Antioxidant Activity of Milk Thistle (Silybum marianum L.) under Rainfed Condition

Milk thistle extract is used to treat liver diseases. The aim of this experiment was to study the effects of micronutrients (Fe, Zn, B, and Mn) on antioxidant activity of milk thistle seed. The study was conducted at the Experimental Fields of Agronomy Department, Faculty of Agriculture and the lab of Biology Department, Urmia University, West Azerbaijan, Iran, during 2016-2017, used randomized complete block design in three replications. Control, Fe, Zn, B and Mn were used as fertilizer treatments. According to the results the effect of micronutrients on total phenols and flavonoids content, nitric oxide radical scavenging, super oxide radical scavenging activity, DPPH radical scavenging activity, and Chainbreaking activity was significant (P ≤ 0.01). Total phenolic content under Zn spraying had significant difference than other treatments whereas in terms of flavonoids content, Zn and B spraying was significant. DPPH radical scavenging activity was higher in Mn and Fe using than other treatments as the difference was significant. Application of mentioned micronutrients significantly decreased the percentage of super oxide and nitric oxide radical scavenging activity than control. In general, according to the findings of this study, spraying micronutrients such as Fe, Zn, B and Mn can be useful to increase the antioxidant capacity of milk thistle under dryland conditions.