Biochemical Changes in Seedlings of Brassica nigra Imposed by Iron and Manganese Induced Heavy Metals Stress

In present study, the seeds of Brassica nigra (variety 1021) were used to evaluate the effect of iron and manganese on different biochemical parameters. The effects of Fe and Mn were studied with regard to pigments composition (proline and carbohydrates contents) of black mustard seedlings under 50 μM, 100 μM and 200 μM concentrations. These concentrations significantly affected the growth of tested seedlings compared to control. Chlorophylls and carbohydrate content also increased at the lower concentrations of Fe and Mn. However, the additional supply of the 5 mM nitrogen in the form of Ca(NO₃)₂ in the nutrient medium somehow reduced the effect of these metals. On the application of nitrogen in the nutrient medium, Fe showed more promotary effect on chlorophylls, carotenoid and carbohydrates content in all concentrations (50 μM, 100 μM and 200 μM). Whereas, Mn exhibited increase in chlorophyll ‘a’, carotenoid and carbohydrate content at 50 μM concentration but these contents significantly decreased at 100 μM and 200 μM concentrations, respectively; while chlorophyll ‘b’ and proline content decreased at all concentrations of the Mn.