Water availability - A physiological constraint on nitrate utilization in plants of Australian semi-arid mulga woodlands

Erskine, P. D., Stewart, G. R., Schmidt, S., Turnbull, M. H., Unkovich, M. and Pate, J. S. (1996) Water availability - A physiological constraint on nitrate utilization in plants of Australian semi-arid mulga woodlands. Plant, Cell and Environment, 19 10: 1149-1159. doi:10.1111/j.1365-3040.1996.tb00430.x


Author Erskine, P. D.
Stewart, G. R.
Schmidt, S.
Turnbull, M. H.
Unkovich, M.
Pate, J. S.
Title Water availability - A physiological constraint on nitrate utilization in plants of Australian semi-arid mulga woodlands
Journal name Plant, Cell and Environment   Check publisher's open access policy
ISSN 0140-7791
1365-3040
Publication date 1996-10
Sub-type Article (original research)
DOI 10.1111/j.1365-3040.1996.tb00430.x
Volume 19
Issue 10
Start page 1149
End page 1159
Total pages 11
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell
Language eng
Formatted abstract
Nitrate was found to be the predominant form of available nitrogen in mulga soils. Nitrate reductase activities on a fresh mass basis of a range of plants from eastern (Queensland) mulga ecosystems 2 weeks after partial relief from drought were uniformly low for both herbaceous species (165 ± 25 pkat g-1) and woody perennials (77 ± 14 pkat g-1). Supply of nitrate for 24 h to cut transpiring shoots of woody species or application of nitrate solution to the rooting zone of herbaceous species promoted little further increase in mean shoot nitrate reductase activities. Most species exhibited high tissue nitrate concentrations during water stress and soluble organic N profiles were in many cases dominated by the osmoprotective compounds, proline or glycine betaine. Species with low levels of proline or glycine betaine showed high foliar concentrations of other compatible osmotica such as polyols or sugars. Effects of relieving water stress on nitrate reductase activity, proline, glycine betaine and nitrate levels were followed over 3 d of irrigation. Available soil nitrate rose 10-fold immediately and, following rapid restoration of leaf water status of the eight study species, a 4-fold increase occurred in mean nitrate reductase activity together with progressive decreases in mean tissue concentrations of nitrate, proline and glycine betaine over the 3 d period. Similar changes in soil nitrate, nitrate reductase activity, proline and tissue nitrate were observed in the same ecosystem following a natural rainfall event and in western (S.W. Australia) mulga following irrigation. It is concluded that, although nitrate nitrogen is present at high concentrations and is the predominant inorganic nitrogen source in soils of the mulga biogeographic region, its assimilation by perennial and ephemeral vegetation is limited primarily by water availability. A scheme is presented depicting interrelated physiological and biochemical events in typical mulga species following a rain event and subsequent drying out of the habitat.
Keyword Glycine betaine
Mulga ecosystem
Nitrate reductase
Polyols
Proline
Water stress
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Agriculture and Food Sciences
 
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