Effect of foliar application of urea, aspartic acid and glutamic acid on growth, physiological and biochemical characteristics of Anise hyssop (Agastache foeniculum)

Anise Hyssop (Agastache foeniculum) is a perennial and aromatic herb plant, belonging to the Lamiaceae family. Its essential oil has antifungal and antibacterial properties and used in food and pharmaceutical industries. To study the effects of foliar application of urea and amino acids on some morpho-physiological and biochemical characteristics of anise hyssop, a pot experiment was conducted in completely randomized design with four replications. The treatments were foliar application of urea (0.5, 1 and 2 g/l), aspartic acid (100, 200 and 300 mg/l), glutamic acid (100, 200 and 300 mg/l) and control (no nitrogen application). The results showed that foliar application of urea and amino acids had significant effects on growth, physiological and biochemical parameters. The highest and the lowest amounts of plant height, leaf number and area, stem diameter, fresh and dry weight of leaves and stems were obtained in 2 g/l of urea and control treatments, respectively. Foliar application of urea and amino acids increased photosynthesis pigments, proline, total soluble sugars, total protein and nitrogen content of leaves compared to control. Total protein, total soluble sugars, proline, leaf chlorophyll and nitrogen content increased as the concentration of amino acids increased. Overall, the findings of this study showed that foliar application of 2 g/l of urea was the most effective treatment for the studied characteristics however amino acids through improvement of growth and physiological characteristics can be used as new sources of nitrogen for plant nutrition.