Abstract
In presence of NH4Cl as the sole source of nitrogen the tomato seedlings absorbed considerable amounts of ammonia-N. The uptake of ammonia was accompanied by cation exchange or efflux of H+ and hence the observed drop in the pH of the medium. Ammonia-N assimilation amounted to 80% of the total ammonium absorption.
On the other hand, feeding with NH4NO3 induced the absorption of both NO −3 and NH +4 ions. Greater amounts of ammonia- than nitrate-N were absorbed except when the highest concentration of NH4NO3 was used. This was reflected in the observed drop in pH values of the corresponding media. As regards assimilation nitrate was always superior to ammonia; the assimilation reached 115%, thus indicating the participation of endogenous nitrate-N in peptide and protein formation.
Ammonia feeding appeared to have a suppressive effect on growth of tomato seedlings. The gain in dry matter seemed to be less with ammonia than with nitrate as the sole source of nitrogen. NH4NO3 as a nitrogen source gave intermediate results between NO −3 and NH +4 .
Ammonia resulting from nitrate reduction or taken up from the media was probably assimilated via glutamine synthetase/glutamate synthase cycle or via glutamic dehydrogenase action. The appearance of detectable amounts of amino- and amide-N in the tissues suggests a possible role of these enzymes in ammonia assimilation.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Barash I, Sandon T and Mor H 1975 Evidence for ammonium-dependentde novo synthesis of glutamate dehydrogenase in detached oat leaves. Plant Physiol 56, 856–8.
Chibnall A C 1939 Protein Metabolism in Plant. Yale University Press, New Haven, Conn. 306 p.
Coic Y, Lesaint C and Le Roux F 1962 Effect de la natrur ammoniacale ou nitrique de L'alimention sur le metabolisme des anions et cations chezla lomate. Ann. Veg. 4, 117–125.
Colgrove M S Jr and Roberts A W 1956 Growth of the azalea influenced by NH4 and nitrate-N Am. Soc. Hort Sci. Proc. 68, 522–536. (Chem. Abstr. 51, 1957).
Dougall D K 1974 Evidence for the presence of glutamate synthase in extracts of carrot cell cultures. Biochem. Biophys. Res. Commun. 58, 639–649.
Gamborg O L 1970 The effect of amino acids and ammonium on the growth of plant cells in suspension culture. Plant Physiol. 45, 372–375.
Givan C V 1979 Metabolic detoxification of ammonia in tissues of higher plants. Phytochem. 18, 375–382.
Holzer H D, Mecke K, Wulff K L and Heilmeyer L J R 1967 Metabolite-induced enzymatic inactivation of glutamine synthetase inE. Col. Advan. Enzyme. Regul. 5, 211–225.
Katsunuma N and Okada M 1965 Effect of ammonia on decrease of pyridine nucleotide levels in isolated rat liver mitochondria. Biochem. Biophys. Res. Commun. 19, 108–113.
Kirkby E A and Mengel K 1967 Ionic balance in different tissues of tomato plant in relation to nitrate, urea, or ammonium nutrition. Plant Physiol. 42, 6–14.
Lea P J and Fowden L 1975 Asparagine metabolism in higher plants. Biochim. Physiol. Pflanzen. 168, 3–14.
Maghrabi Y M S, Younis A E and Abozinah F S 1984 Nitrogen metabolism in tomato seedlings. I. Uptake and assimilation of nitrate-N. Plant and Soil 85, 395–402.
Ozaki K and Sasaki 1956 Assimilation of NH4−N in rice plant operating shortly after the application of N15 labelled (NH4)2SO4. Soil and Plant Food (Tokyo) 2, 25–27. (Chem. Abstr. 51, 4505, 1957).
Rognes S E 1975 Glutamine-dependent asparagine synthetase fromLupinus luteus. Phytochem. 15, 873.
Schubert R and Coker G T 1981 Ammonia assimilation inAlnus glutinosa andGlycine max. Plant Physiol. 67, 662–665.
Skokut A T, Peter Wolk Co., Thomas J Meeks J C and Shaffer P W 1978 Initial organic products of assimilation of (N15) ammonium and (N13) nitrate by Tobacco cells cultured on different sources of nitrogen. Plant Physiol. 62, 299–304.
Steward F C and Bidwell R S G 1966 Storage pool and turnover systems in growing and non growing cells: Experiments with C14 glutamine and C14-asparagine. J. Exp. Bot. 17, 726.
Syrett P J 1953 The assimilation of ammonia by nitrogen-starved cells ofChlorella vulgaris. II. The assimilation of ammonia to other compounds. Ann. Bot., N.S. 17, 21–36.
Tamm C O 1956 Response ofEpilobium angustifolium to different nitrogen sources in water culture. Physiol. Plant. 9, 331–336. (Chem. Abstr. 52, 13026 g, 1958).
Wallace A and Mueller R T 1957 Ammonia and nitrate-N absorption from sand culture by rough lemon cuttings. Am. Soc. Hort. Sci. Proc. 69, 183–188. (Chem. Abstr. 51, 18431, 1957).
Weissman G S 1951 Nitrogen metabolism of wheat seedlings as influenced by the ammonium: nitrate ratio and the hydrogen-ion concentration. Am. J. Bot. 38, 162–174.
Weissman G S 1959 Influence of ammonium and nitrate on the protein and free amino acids in shoot of wheat seedlings. Am. J. Bot. 46, 379–346.
Wood J G 1953 Nitrogen metabolism of higher plants. Ann. Rev. Plant. Physiol. 4, 1–22.
Younis A E 1961 Assimilation of ammonia by radish root slices. Acta. Biol. Hung. 12, 147–152.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Maghrabi, Y.M.S., Younis, A.E. & Abozinah, F.S. Nitrogen metabolism in tomato seedlings. Plant Soil 85, 403–411 (1985). https://doi.org/10.1007/BF02220195
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF02220195