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Impact of Temperature on the Relationship between Respiration and Nitrogen Concentration in Roots: An Analysis of Scaling Relationships, Q10 Values and Thermal Acclimation Ratios
Lindsey J. Atkinson, Martin A. Hellicar, Alastair H. Fitter and Owen K. Atkin
The New Phytologist
Vol. 173, No. 1 (2007), pp. 110-120
Stable URL: http://www.jstor.org/stable/4131278
Page Count: 11
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$\bullet$ The impact of nitrogen (N) supply on the temperature response of root respiratory O2 uptake (R) was assessed in several herbaceous species grown in solution culture. Warm-grown ($25 : 20\textdegree C$, day:night) plants differing in root N concentration were shifted to $13 : 8\textdegree C$ for 7 d to cold-acclimate. $\bullet$ Log-log plots of root R vs root N concentration both showed that R increased with increasing tissue N concentration, irrespective of the growth temperature. Although the regression slopes of the log-log plots did not differ between the warm-grown and cold-acclimated plants, cold-acclimated plants did exhibit a higher y-axis intercept than their warm-grown counterparts. This suggests that cold acclimation of root R is not entirely dependent on cold-induced increases in tissue N concentration and that scaling relationships (i.e. regression equations fitted to the log-log plots) between root R and N concentration are not fixed. $\bullet$ No systematic differences were found in the short-term Q10 (proportional change in R per 10° C change in temperature), or degree of cold acclimation (as measured by the proportional difference between warm- and cold-acclimated roots) among roots differing in root N concentration. The temperature response of root R is therefore insensitive to tissue N concentration. $\bullet$ The insensitivity of Q10 values and acclimation to tissue N concentration raises the possibility that root R and its temperature sensitivity can be predicted for a range of N supply scenarios.
The New Phytologist © 2007 New Phytologist Trust