Effect of Nitrogen Fertilization on Yield and Quality of Some Salad Crops

The present experiments were carried out at the Assiut Univ. Experimental Farm during two winter seasons, 1994/1995 and 1995/1996, to study the effect of nitrogen source and level on growth, yield, and quality of salad crops (lettuce, parsley, and roquette). Nitrogen sources were urea, ammonium nitrate, and ammonium sufate. Three nitrogen levels, namely 20, 40, and 80 kg N/feddan, in addition to organic manure (2.028% N), in addition to the control, were used. Plant height, number of leaves (parsley and roquette), number of non-edible leaves (in lettuce) were significantly increased with urea followed by ammonium nitrate. Plant fresh weight, weight of edible part (in lettuce), and total yield/feddan were significantly higher with urea than ammonium nitrate or ammonium sulfate. The lowest content of nitrate and nitrite in leaves of the salad crops was obtained with ammonium sulfate followed by ammonium nitrate, while urea gave the highest values. Application of organic manure produced plant height, number of leaves per plant, plant fresh weight, total yield, dry matter content almost equal to that obtained from 40 or 20 kg N/fed. Nitrate and nitrite content were at their lowest value when organic manure was used. Plant height, number of leaves, non-edible leaves, weight of plant and total yield/feddan were significantly increased with increasing nitrogen rates from 0 to 80 kg/feddan. Using 80 kg N/fed. gave the highest dry matter, nitrate, and nitrite content.