Effect of repeated applications of gamma-hexachlorocyclohexane (γ-HCH) on nitrogenase activity and nitrogen-fixing bacteria associated with rhizosphere of tropical rice

• Published in: Microbiological research 1996-12, Vol.151 (4), p.375-378
• Main Authors: Patnaik, G.K., Kanungo, P.K., Adhya, T.K., Rajaramamohan Rao, V.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; associative nitrogenase activity; Biochemistry and biology; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Microbiology; Oryza sativa; Physics, chemistry, biochemistry and biology of agricultural and forest soils; rice rhizosphere; Soil science; γ-HCH
• ISSN: 0944-5013; 1618-0623
• DOI: 10.1016/S0944-5013(96)80006-1

In a greenhouse study, the influence of repeated applications of γ-HCH on the nitrogenase activity and nitrogenfixing bacterial populations associated with the rhizosphere of tropical rice was studied. Repeated applications of γ-HCH up to three caused a significant stimulation of rhizosphere associated nitrogenase activity which declined with time. After the 4 th application, the nitrogenase activity was further enhanced compared with the nitrogenase activity in other series at that time. The populations of nitrogen-fixing Azotobacter and Azospirillum were progressively stimulated with repeated additions of γ-HCH, while the population of anaerobic nitrogen-fixing bacteria was inhibited. Results suggest a selective stimulation and/or creation of favourable conditions for specific nitrogenfixing bacterial population and their activity associated with rice rhizosphere following repeated applications of γ-HCH.