EFFECT OF NITROGEN FERTILIZATION AND ASCORBIC ACID ON GROWTH, ESSENTIAL OIL AND CHEMICAL COMPOSITION OF ROSEMARY PLANT

Abstract

A pot experiment was carried out during 2014 and 2015 seasons to study the effect of nitrogen fertilization (0, 1, 2 and 3 g N pot-1) in the form of calcium nitrate Ca (NO 3) 2 (15.5% N) and four spray levels with ascorbic acid (0, 50 and 100 ppm) on growth, essential oil content and chemical composition of rosemary plant. Plastic pots of 25 cm diameter were used. Experimental treatments were laid out in a split plot design. Tow cuts were taken each season. Application of nitrogen up to 3 g N pot-1 enhanced all studied growth parameters in terms of plant height, number of branches, fresh and dry weight of leaves as well as total chlorophyll, total carbohydrates, N, P, K contents. Essential oil content was enhanced by adding of nitrogen up to 2 g N pot-1 , thereafter more increase in nitrogen, significantly decreased essential oil content. Spraying rosemary plants with ascorbic acid up to 100 ppm, significantly enhanced plant height, branch number, fresh and dry weight of leaves and essential oil content as well as total chlorophyll, total carbohydrates, N, P and K contents. Rosemary plants fertilized with 3 g N pot-1 and sprayed with 100 ppm ascorbic acid gave the highest value of each of plant height, number of branches, fresh and dry weight of leaves, total chlorophyll and total carbohydrates, while the highest essential oil percentage was obtained from plants fertilized with 2 g N pot-1 and sprayed with 100 ppm of ascorbic acid. Alpha-pinene, Eucalyptol, Linalool, Camphor, Endo-borneol and Cis-pinane were the major constituents of the essential oil profile, over all combinations of nitrogen and ascorbic acid levels in both cuts.