Effects of Macro- and Nano-cobalt Oxide Particles on Barley Seedlings and Remediation of Cobalt Chloride Toxicity Using Sodium Hypochlorite

This study was undertaken to determine the comparative effects of cobalt (II, III) oxide (Co3O4) macro- and nano-particles and cobaltous chloride hexahydrate (CoCl2.6H2O) on seed germination, growth and some biochemical parameters of Hordeum vulgare L. seedlings. Macro- and nano-Co was added to the sand medium at four levels (50 to 200 mg kg-1 sand). Macro-Co was found to increase the growth of both shoots and roots at concentrations up to 200 mg Co kg-1 sand. Increase in concentration of nano-Co decreased the root length. Lipid peroxidation was maximum at 200 mg Co kg-1 sand for macro-Co in roots. Increase in the lipid peroxidation was found in nano-Co treated roots and shoots. Nano- and macro-Co3O4 behaved differently with respect to effects on barley seedlings. The present study also demonstrated the ameliorative effect of NaOCl against CoCl2.6H2O toxicity in barley seedlings. NaOCl also decreased the lipid peroxidation induced by CoCl2.6H2O and increased chlorophyll content in seedlings.