The Effect of Micronutrients Supplementation (Fe, Zn, B, and Mn) on AntioxidantActivity 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 ofagronomy 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 wereused 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 chainbreakingactivity was significant (p ≤ 0.01). total phenolic content under zn spraying had significant difference than othertreatments whereas in terms of flavonoids content, zn and b spraying was significant. dpph radical scavenging activitywas higher in mn and fe using than other treatments as the difference was significant. application of mentionedmicronutrients significantly decreased the percentage of super oxide and nitric oxide radical scavenging activity thancontrol. in general, according to the findings of this study, spraying micronutrients such as fe, zn, b and mn can be usefulto increase the antioxidant capacity of milk thistle under dryland conditions.