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Journal of Environmental Quality Abstract -

Photosynthesis and Nitrogen Fixation in Soybean Exposed to Nitrogen Dioxide and Carbon Dioxide


This article in JEQ

  1. Vol. 21 No. 4, p. 624-626
    Received: Dec 2, 1991

    * Corresponding author(s):
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  1. Gian Gupta *,
  2. Yuncong Li and
  3. Ravinder Sandhu
  1. Dep. of Agricultural Sciences, Univ. of Maryland Eastern Shore, Princess Anne, MD 21853.



‘Williams-82’ Soybean [Glycine max (L.) Merr.] plants, at the flowering stage, were exposed to NO2 (0.1 µmol mol−1, 7 h d−1) and CO2 (450 µmol mol−1, 12 h d−1) for 5 d singly and in combination in open-top field chambers. The rate of photosynthesis (PN), specific root nodule nitrogenase activity (SNA), and leaf N were measured after exposure using the LICOR 6200 Portable Photosynthesis system, the acetylene-ethylene reduction method, and the Kjeldahl digestion, respectively. The plants exposed to NO2 (with 350 µmol mol−1 CO2) showed significantly higher PN, SNA, and N compared with the control plants. The SNA and N were reduced, with no change in PN on exposing the plants to CO2 (in the absence of NO2). When the plants were exposed to a combination of these two gases, SNA was increased but the PN and N did not change. The stimulatory effect of NO2 was reduced by the inhibitory impact of CO2 on the parameters studied.

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