Abstract
Pisum sativum L. cv. Trapper plants were inoculated and grown in a controlled environment on N-free nutrient solution. After 4 weeks N was supplied to treatment plants as NH4NO3, KNO3, or NH4Cl and rates of C2H2 reduction, root + nodule respiration, and leaf photosynthesis were determined 1 week later. The increase in respiration per unit of C2H2 reduction was not affected by either the form of N added or the light conditions during growth, although the basal respiration rate with no C2H2 reduction increased with irradiance level. The mean regression coefficient from plots of respiration versus C2H2 reduction was 0.23 + 0.04 (P [unk] .01) mg of CO2 (μmol of C2H2 reduced)−1 which was very similar to the value for the coefficient of respiration associated with nitrogenase activity estimated by subtracting growth and maintenance respiration. Since the rate of N accumulation in N-free nutrient conditions was proportional to the rate of C2H2 reduction, it appears that the method gives a true estimate of the energy requirements for N fixation which for these conditions was equivalent to 17 grams of carbohydrate consumed per gram of N fixed.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Chen P. C., Phillips D. A. Induction of Root Nodule Senescence by Combined Nitrogen in Pisum sativum L. Plant Physiol. 1977 Mar;59(3):440–442. doi: 10.1104/pp.59.3.440. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hardy R. W., Havelka U. D. Nitrogen fixation research: a key to world food? Science. 1975 May 9;188(4188):633–643. doi: 10.1126/science.188.4188.633. [DOI] [PubMed] [Google Scholar]
- Mahon J. D. Root and nodule respiration in relation to acetylene reduction in intact nodulated peas. Plant Physiol. 1977 Dec;60(6):812–816. doi: 10.1104/pp.60.6.812. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schubert K. R., Evans H. J. Hydrogen evolution: A major factor affecting the efficiency of nitrogen fixation in nodulated symbionts. Proc Natl Acad Sci U S A. 1976 Apr;73(4):1207–1211. doi: 10.1073/pnas.73.4.1207. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thornley J. H. Respiration, growth and maintenance in plants. Nature. 1970 Jul 18;227(5255):304–305. doi: 10.1038/227304b0. [DOI] [PubMed] [Google Scholar]
- VAN NIEL C. B., ALLEN M. B., WRIGHT B. E. On the photochemical reduction of nitrate by algae. Biochim Biophys Acta. 1953 Sep-Oct;12(1-2):67–74. doi: 10.1016/0006-3002(53)90124-3. [DOI] [PubMed] [Google Scholar]