Growth, nitrogen uptake, and metabolism in two semiarid shrubs grown at ambient and elevated atmospheric CO 2 concentrations: effects of nitrogen supply and source
The effect of differences in nitrogen (N) availability and source on growth and nitrogen metabolism at different atmospheric CO 2 concentrations in Prosopis glandulosa and Prosopis flexuosa (native to semiarid regions of North and South America, respectively) was examined. Total biomass, allocation,...
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Published in | American journal of botany Vol. 91; no. 4; pp. 565 - 572 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
01.04.2004
|
Online Access | Get full text |
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Summary: | The effect of differences in nitrogen (N) availability and source on growth and nitrogen metabolism at different atmospheric CO
2
concentrations in
Prosopis glandulosa
and
Prosopis flexuosa
(native to semiarid regions of North and South America, respectively) was examined. Total biomass, allocation, N uptake, and metabolites (e.g., free NO
3
−
, soluble proteins, organic acids) were measured in seedlings grown in controlled environment chambers for 48 d at ambient (350 ppm) and elevated (650 ppm) CO
2
and fertilized with high (8.0 mmol/L) or low (0.8 mmol/L) N (N
level
), supplied at either 1 : 1 or 3 : 1 NO
3
−
: NH
4
+
ratios (N
source
). Responses to elevated CO
2
depended on both N
level
and N
source
, with the largest effects evident at high N
level
. A high NO
3
−
: NH
4
+
ratio stimulated growth responses to elevated CO
2
in both species when N was limiting and increased the responses of
P. flexuosa
at high N
level
. Significant differences in N uptake and metabolites were found between species. Seedlings of both species are highly responsive to N availability and will benefit from increases in CO
2
, provided that a high proportion of NO
3
‐ to NH
4
‐N is present in the soil solution. This enhancement, in combination with responses that increase N acquisition and increases in water use efficiency typically found at elevated CO
2
, may indicate that these semiarid species will be better able to cope with both nutrient and water deficits as CO
2
levels rise. |
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ISSN: | 0002-9122 1537-2197 |
DOI: | 10.3732/ajb.91.4.565 |