Abstract
The results indicated that addition of (82.5 and 95) g/L NH4NO3 and KNO3 respectively to MS medium enhanced greatly shoot formation after (60) days of growth. The MS medium supplemented with (16.5 and 19) g/L NH4NO3 and KNO3 respectively greatly promote the formation of large number of roots. The best medium sustained callus growth was MS medium supplemented with (16.5 and 285)g/L NH4NO3 and KNO3 respectively. Moreover fresh weight reached (18.76)g compared with (15.33)g that on standard medium, with increase in protein in the latter medium reach 0.550 mg/g as compared with 0.520 mg/g on standard medium after (60) days of growth. It can be concluded that the addition of potassium nitrate to standard nutrient medium at different concentrations enhanced the growth and differentiation of lettuce plant callus compared with ammonium nitrate.