Effect of iron and zinc foliar application on some biochemical traits of Thymus (Thymus vulgaris L.) plant under nitrogen deficiency

One of the most important causes limiting the growth of plants is soil nutrient deficiency. Nitrogen is considered as one of the essential nutrients for plant production and its deficiency is common in many parts of the country. One of the ways to provide nutrients for plants is foliar application of them. In present study the effect of soluble micronutrients (iron and zinc) on some of the biochemical traits of thyme, including length and dry weights of root and leaf, leaf area, relative water content, chlorophyll, soluble sugar and proline contents and catalase and ascorbate peroxidase enzymes activity and essential oil constitutes was evaluated under nitrogen deficiency. Treatments included nitrogen deficiency at two levels of normal and deficiency and foliar spraying of micronutrients (iron and zinc) in three levels of control, one percent and two percent of the source iron sulfate and zinc sulfate. The results showed nitrogen deficiency reduced the chlorophyll content and increased carotenoids content compare to control. soluble sugar and proline contents and the activity of antioxidant enzymes increased in roots and leaves of thyme plant in nitrogen deficiency conditions. Spraying micronutrients improved nitrogen deficiency conditions, and in general, zinc nutrient had a more significant effect on biochemical factors compare to iron. The main constitute of thyme essential oil was thymol, that increased under nitrogen deficiency and also leaf nutrition by micronutrients. There was a significant correlation (P0.7) between catalase activity and ascorbate peroxidase activity of plant.