Plant and Soil

, Volume 82, Issue 1, pp 15–29 | Cite as

An intact plant assay for estimating nitrogenase activity (C2H2 reduction) of sorghum and millet plants grown in pots

  • S. P. Wani
  • M. N. Upadhyaya
  • P. J. Dart


A non destructive intact-plant assay for estimating nitrogenase activity (C2H2 reduction) of pot-grown sorghum and millet plants is described. Plants with intact shoots sustained more activity than plants whose tops were removed prior to the assay. With this technique individual plants can be assayed several times during their life cycle. The C2H2 reduction was linear up to 16h incubation in this assay procedure. More rapid diffusion of C2H2 was achieved by injection through a Suba seal in the bottom of the pot. The equlibration of injected C2H2 in the gas phase of the pots filled with sand and sand:FYM media was completed within 1 h. Significantly higher nitrogenase activity and better growth of sorghum and millet plants occurred when plants were grown in a mixture of sand and farmyard manure (FYM) than when plants were grown in vermiculite, soil, or sand + soil medium. Nitrogenase activity and plant growth were greater in a mixture of sand with 2 and 3% FYM than with 0.5 and 1% FYM. Activity was higher when the plants were incubated at 33°C and 40°C than at 27°C. Activity also increased with increasing soil moisture. There were significant differences amongst 15 sorghum cultivars screened for associated nitrogenase activity. This new technique has good prospects for screening cultivars of millet, sorghum and other grain crops for their nitrogen-fixing ability.

Key words

C2H2 reduction Intact-plant assay Millet Nitrogen fixation Nitrogenase activity Sorghum 


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Copyright information

© Martinus Nijhoff/Dr W. Junk Publishers 1984

Authors and Affiliations

  • S. P. Wani
    • 1
  • M. N. Upadhyaya
    • 1
  • P. J. Dart
    • 1
  1. 1.International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)India

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