title: Influence of ammonium chloride on the nitrogenase activity of nodulated pea plants (Pisum sativum).
abstract: A study was made on the short-term effect of ammonium ions on the nitrogenase activity of pea root nodules. Nodulated pea plants (Pisum sativum), having reached maximum acetylene-reducing activity, were supplied with NH4Cl (20 mM). Nitrogenase activity of intact plants, detached nodules, and isolated bacteroids was measured at differed time intervals. A significant drop (20 to 40%) in the acetylene-reducing activity of treated intact plants and their detached nodules was observed after 1 day. No drop in the nitrogenase activity of bacteroids (assayed aerobically, or anaerobically after treatment with ethylenediaminetetraacetic acid-toluene) occurred for 2 to 4 days after the addition of NH4+ to the plants, depending on cultural conditions. From these results it is concluded that the adverse effect of NH4+ on acetylene reduction by intact plants and detached nodules during the first 2 days is not due to a decrease in the amount of nitrogenase in the bacteroids. It is suggested that the effect has to be attributed to a reduced supply to the bacteroids of energy-delivery photosynthates.
mesh_terms: D000643:Ammonium Chloride / Q000494:pharmacology*; D007887:Fabaceae / Q000201:enzymology / Q000382:microbiology*; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000378:metabolism*; D010946:Plants, Medicinal; D011189:Potassium Chloride / Q000494:pharmacology; D012231:Rhizobium / Q000201:enzymology*; D012988:Soil Microbiology; D013559:Symbiosis
chemical_list: D000643:Ammonium Chloride; D011189:Potassium Chloride; D009591:Nitrogenase