A new method of determination of nitrate was developed, utilizing the nitrate reductase activity of Paracoccus denitrificans in which a further reduction of nitrate is blocked either by a mutation affecting formation of cytochromes c or by inhibition of the electron flow to nitrite reductase by mucidin. After deproteinization of the sample with zinc acetate the nitrite produced is determined colorimetrically.
Effect of nitrate on the nitrogenase (C2H2-reduction) activity, growth of nodule tissue accumulation of nitrate and nitrate reductase activity in 4-weeks-old nodulated peas (Pisum sativum L.) was investigated. A relatively slow decrease of the total nitrogenase activity (mumol C2H4 per root per h), as compared with plants cultivated without nitrate, was due to both retardation of further growth of the nodule tissue and to a decrease of their specific nitrogenase activity (mumol C2H4 per gf.wt. per h). However, an absolute and pronounced decrease of both nitrogenase activities occurred only 4 or 7 d after the application of nitrate. The addition of nitrate led to its rapid accumulation in the nodule and leaf tissue with a simultaneous induction of the nitrate reductase activity. The nitrogenase activity was not completely inhibited even after a 7-d cultivation with 280 m NO3- -N in the nutrient medium and after accumulation of up to 180 ppm NO3- -Nf.wt. in the nodule tissue. The results obtained indicate that the "photosynthate deprivation" reflects competition between assimilation of nitrate and fixation of dinitrogen.
- MeSH
- časové faktory MeSH
- chemická deprese MeSH
- dusičnany aplikace a dávkování MeSH
- dusík metabolismus MeSH
- Fabaceae účinky léků metabolismus MeSH
- fotosyntéza MeSH
- kultivační média farmakologie MeSH
- kultivační techniky MeSH
- léčivé rostliny * MeSH
- nitrátreduktasy antagonisté a inhibitory metabolismus MeSH
- nitrogenasa metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
