Amino acids as metal complexing agents have the ability of forming relatively stable complexes with zinc (Zn) and iron (Fe) thereby increase their availability for plants. In this study, the complexes of Fe, [Fe(L-L') 2 ] and Zn, [Zn(L-L') 2 ] (where L-L' = monoanion of arginine, glycine, glutamine and histidine) were synthesized and used to determine their effects on the antioxidant, yield and nutritional quality of plant. Results indicated that using Fe- and Zn-aminochelates in the nutrient solution could supply sufficient amount of Zn and Fe for plant uptake and also improved root and shoot growth of lettuce and tomato plants. Our results showed that Fe-aminochelates alleviated salt-stress induced oxidative damages on two tomato cultivars grown in nutrient solution culture. This was accompanied with higher uptake of N, K, Fe, and Zn by tomato shoots as well as elevated activity of catalase and ascorbate peroxidase. The effectiveness of foliar spray of Zn- and Fe-aminochelates on the yield and grain quality of two different Zn-deficiency tolerant wheat cultivars was also investigated under field conditions. The results indicated that aminochelates not only increase the concentration of Zn and Fe in wheat grains, but makes them more bioavailable for human. According to the results obtained in this study, the Zn- and Fe aminochelates should be considered as new Zn and Fe fertilizer sources for improving yield and quality of crops. Key Words: amino acid, iron, zinc, chelate, antioxidant capacity.
