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Impact of gaseous nitrogen deposition on plant functioning
Author(s) -
STULEN I.,
PEREZSOBA M.,
DE KOK L. J.,
VAN DER EERDEN L.
Publication year - 1998
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.1998.00179.x
Subject(s) - glutamate synthase , glutamine synthetase , nitrate reductase , nitrite reductase , apoplast , fumigation , chemistry , nitrogen , nitrate , environmental chemistry , nitrite , nitrogen cycle , pollutant , nitrogen assimilation , botany , glutamine , enzyme , biochemistry , horticulture , biology , cell wall , amino acid , organic chemistry
Dry deposition of NH 3 and NO x (NO and NO 2 ) can affect plant metabolism at the cellular and whole‐plant level. Gaseous pollutants enter the plant mainly through the stomata, and once in the apoplast NH 3 dissolves to form NH 4 + , whereas NO 2 dissolves to form NO 3 − and NO 2 − . The latter compound can also be formed after exposure to NO. There is evidence that NH 3 ‐N and NO x ‐N can be reversibly stored in the apoplast. Temporary storage might affect processes such as absorption rate, assimilation and re‐emission. Once formed, NO 3 − and NO 2 − can be reduced, and NH 4 + can be assimilated via the normal enzymatic pathways, nitrate reductase (NR), nitrite reductase and the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle. Fumigation with low concentrations of atmospheric NH 3 increases in vitro glutamine synthetase activity, but whether this involves both or only one of the GS isoforms is still an open question. There seems to be no correlation between fumigation with low concentrations of NH 3 and in vitro GDH activity. The contribution of atmospheric NH 3 and NO 2 deposition to the N budget of the whole plant has been calculated for various atmospheric pollutant concentrations and relative growth rates ( RGRs ). It is concluded that at current ambient atmospheric N concentrations the direct impact of gaseous N uptake by foliage on plant growth is generally small.