Effect of cobalt on growth,yield and chemical constituents of Nigella sativa L.

Cobalt ion (co2+) is considered a beneficial element for higher plants due to its direct role in their metabolism. nigella sativa l. (n. sativa) is a widely used medicinal plant throughout the world. the aim of this study was to evaluate the influence of co2+ on n. sativa growth,yield and chemical constituents. nigella sativa l. plants were subjected to different rates of co2+ to study the influence of co2+ on growth,yield and chemical constituents. the growth characters [plant height (cm),number of leaves (plant-1),number of branches (plant-1),number of capsules (plant-1),herb dry weight (plant-1) and seed yield (plant-1)] increased as the concentration of co2+ increased. the highest values of growth characters (45.8,55.8,13.7,39.1,19.6 and 9.7) were observed at 30 mg l-1. the highest essential and fixed oil contents (0.5% and 24.1%) were recorded at 40 mg l-1. the highest values of total carbohydrate,soluble sugars and protein contents resulted from the treatment of 30 mg l-1,the increases in total carbohydrate,soluble sugars and protein were 47%,140% and 44.4% higher than the control treatment. the treatment with 30 mg l-1 resulted in the highest npk accumulation (3.9,0.6 and1.4%). the highest n and k uptakes (0.8% and 0.3%) were recorded in the treatment of 30 mg l-1. no changes occurred in p uptake under co2+ concentrations. the lowest values of growth characters and chemical constituents were observed in control treatment (0.0 mg l-1).