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13C and 15N allocations of two alpine species from early and late snowmelt locations reflect their different growth strategies.

Baptist F, Tcherkez G, Aubert S, Pontailler JY, Choler P, Nogués S - J. Exp. Bot. (2009)

Bottom Line: Furthermore, assimilates transferred to the roots were preferentially used for growth rather than respiration and tended to favour N reduction in this compartment.Accordingly, this species had higher (15)N uptake efficiency than KM and a higher translocation of reduced (15)N to aboveground organs.These results suggest that at the whole-plant level, there is a compromise between N acquisition/reduction and C allocation patterns for optimized growth.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire d'Ecologie Alpine, UMR CNRS-UJF 5553, Université de Grenoble, BP 53, F-38041 Grenoble Cedex 09, France. florence.baptist@ujf-grenoble.fr

ABSTRACT
Intense efforts are currently devoted to disentangling the relationships between plant carbon (C) allocation patterns and soil nitrogen (N) availability because of their consequences for growth and more generally for C sequestration. In cold ecosystems, only a few studies have addressed whole-plant C and/or N allocation along natural elevational or topographical gradients. (12)C/(13)C and (14)N/(15)N isotope techniques have been used to elucidate C and N partitioning in two alpine graminoids characterized by contrasted nutrient economies: a slow-growing species, Kobresia myosuroides (KM), and a fast-growing species, Carex foetida (CF), located in early and late snowmelt habitats, respectively, within the alpine tundra (French Alps). CF allocated higher labelling-related (13)C content belowground and produced more root biomass. Furthermore, assimilates transferred to the roots were preferentially used for growth rather than respiration and tended to favour N reduction in this compartment. Accordingly, this species had higher (15)N uptake efficiency than KM and a higher translocation of reduced (15)N to aboveground organs. These results suggest that at the whole-plant level, there is a compromise between N acquisition/reduction and C allocation patterns for optimized growth.

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Related in: MedlinePlus

(a) Labelling-derived 13C content of new roots in relation to labelling-derived 13C content of leaves and (b) labelling-derived 13C content of CO2 respired by the new roots in relation to the labelling-derived 13C content of CO2 respired by the leaves for K. myosuroides (filled symbols) and C. foetida (open symbols) at each chase time. Values are the mean ±SE (n=3). See text for further statistical details.
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fig2: (a) Labelling-derived 13C content of new roots in relation to labelling-derived 13C content of leaves and (b) labelling-derived 13C content of CO2 respired by the new roots in relation to the labelling-derived 13C content of CO2 respired by the leaves for K. myosuroides (filled symbols) and C. foetida (open symbols) at each chase time. Values are the mean ±SE (n=3). See text for further statistical details.

Mentions: The labelling-derived quantity of 13C (γ13C) in new roots is plotted against that of leaves in Fig. 2. There was a significant correlation between the γ13C value of new roots and that of leaves when the species were considered together (F1,22=46.1, R2=0.71, P <0.0001, Fig. 2a). The slope of the regression was slightly (but not significantly) steeper in CF, again showing more rapid 13C kinetics in leaves. In addition, the more rapid transfer of carbon from leaves to roots was reflected by the shift of data points from the right-hand side (T0) to the left-hand side (the chase measurements, at T1–T3, clustered on the left, Fig. 2A, open symbols) in CF, while there were intermediate data points in KM. γ13CR values of leaf-respired CO2 and root-respired CO2 were correlated (F1,23=22.2, R2=0.56, P=0.0001, Fig. 2b) when species were considered together. However, neither the slope of the regression (F1,23=0.44, P=0.51) nor the mean value (F1,23=2.57, P=0.12) differed between the two species.


13C and 15N allocations of two alpine species from early and late snowmelt locations reflect their different growth strategies.

Baptist F, Tcherkez G, Aubert S, Pontailler JY, Choler P, Nogués S - J. Exp. Bot. (2009)

(a) Labelling-derived 13C content of new roots in relation to labelling-derived 13C content of leaves and (b) labelling-derived 13C content of CO2 respired by the new roots in relation to the labelling-derived 13C content of CO2 respired by the leaves for K. myosuroides (filled symbols) and C. foetida (open symbols) at each chase time. Values are the mean ±SE (n=3). See text for further statistical details.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2692016&req=5

fig2: (a) Labelling-derived 13C content of new roots in relation to labelling-derived 13C content of leaves and (b) labelling-derived 13C content of CO2 respired by the new roots in relation to the labelling-derived 13C content of CO2 respired by the leaves for K. myosuroides (filled symbols) and C. foetida (open symbols) at each chase time. Values are the mean ±SE (n=3). See text for further statistical details.
Mentions: The labelling-derived quantity of 13C (γ13C) in new roots is plotted against that of leaves in Fig. 2. There was a significant correlation between the γ13C value of new roots and that of leaves when the species were considered together (F1,22=46.1, R2=0.71, P <0.0001, Fig. 2a). The slope of the regression was slightly (but not significantly) steeper in CF, again showing more rapid 13C kinetics in leaves. In addition, the more rapid transfer of carbon from leaves to roots was reflected by the shift of data points from the right-hand side (T0) to the left-hand side (the chase measurements, at T1–T3, clustered on the left, Fig. 2A, open symbols) in CF, while there were intermediate data points in KM. γ13CR values of leaf-respired CO2 and root-respired CO2 were correlated (F1,23=22.2, R2=0.56, P=0.0001, Fig. 2b) when species were considered together. However, neither the slope of the regression (F1,23=0.44, P=0.51) nor the mean value (F1,23=2.57, P=0.12) differed between the two species.

Bottom Line: Furthermore, assimilates transferred to the roots were preferentially used for growth rather than respiration and tended to favour N reduction in this compartment.Accordingly, this species had higher (15)N uptake efficiency than KM and a higher translocation of reduced (15)N to aboveground organs.These results suggest that at the whole-plant level, there is a compromise between N acquisition/reduction and C allocation patterns for optimized growth.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire d'Ecologie Alpine, UMR CNRS-UJF 5553, Université de Grenoble, BP 53, F-38041 Grenoble Cedex 09, France. florence.baptist@ujf-grenoble.fr

ABSTRACT
Intense efforts are currently devoted to disentangling the relationships between plant carbon (C) allocation patterns and soil nitrogen (N) availability because of their consequences for growth and more generally for C sequestration. In cold ecosystems, only a few studies have addressed whole-plant C and/or N allocation along natural elevational or topographical gradients. (12)C/(13)C and (14)N/(15)N isotope techniques have been used to elucidate C and N partitioning in two alpine graminoids characterized by contrasted nutrient economies: a slow-growing species, Kobresia myosuroides (KM), and a fast-growing species, Carex foetida (CF), located in early and late snowmelt habitats, respectively, within the alpine tundra (French Alps). CF allocated higher labelling-related (13)C content belowground and produced more root biomass. Furthermore, assimilates transferred to the roots were preferentially used for growth rather than respiration and tended to favour N reduction in this compartment. Accordingly, this species had higher (15)N uptake efficiency than KM and a higher translocation of reduced (15)N to aboveground organs. These results suggest that at the whole-plant level, there is a compromise between N acquisition/reduction and C allocation patterns for optimized growth.

Show MeSH
Related in: MedlinePlus