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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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δ13C (‰) of leaves, and new and old roots of K. myosuroides (a) and C. foetida (b). δ13C (‰) of CO2 respired by the leaves, and new and old roots of K. myosuroides (c) and C. foetida (d) following pulse labelling. On the left of the dashed vertical line is shown the natural abundance of 13C in the OM of leaves, and new and old roots, and the CO2 respired by the leaves, and the new and the old roots. Leaves, open circles; new roots, open squares; old roots, filled squares. All x-axes show the time elapsed since pulse labelling (in days). Values are the mean ±SE (n=3).
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fig1: δ13C (‰) of leaves, and new and old roots of K. myosuroides (a) and C. foetida (b). δ13C (‰) of CO2 respired by the leaves, and new and old roots of K. myosuroides (c) and C. foetida (d) following pulse labelling. On the left of the dashed vertical line is shown the natural abundance of 13C in the OM of leaves, and new and old roots, and the CO2 respired by the leaves, and the new and the old roots. Leaves, open circles; new roots, open squares; old roots, filled squares. All x-axes show the time elapsed since pulse labelling (in days). Values are the mean ±SE (n=3).

Mentions: The 12C/13C isotope composition (δ13C) of OM and of respired CO2 after labelling is shown in Fig. 1. Clearly, at T0, leaves were the most labelled organs, followed by new roots (Fig. 1). Old roots showed a low degree of labelling throughout the experiment (i.e. until the end of the chase time). The kinetics were very different for leaves and roots: the δ13C value of leaves continuously declined during the chase time while that of new roots increased within 1.5 d and reached a plateau.


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)

δ13C (‰) of leaves, and new and old roots of K. myosuroides (a) and C. foetida (b). δ13C (‰) of CO2 respired by the leaves, and new and old roots of K. myosuroides (c) and C. foetida (d) following pulse labelling. On the left of the dashed vertical line is shown the natural abundance of 13C in the OM of leaves, and new and old roots, and the CO2 respired by the leaves, and the new and the old roots. Leaves, open circles; new roots, open squares; old roots, filled squares. All x-axes show the time elapsed since pulse labelling (in days). Values are the mean ±SE (n=3).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig1: δ13C (‰) of leaves, and new and old roots of K. myosuroides (a) and C. foetida (b). δ13C (‰) of CO2 respired by the leaves, and new and old roots of K. myosuroides (c) and C. foetida (d) following pulse labelling. On the left of the dashed vertical line is shown the natural abundance of 13C in the OM of leaves, and new and old roots, and the CO2 respired by the leaves, and the new and the old roots. Leaves, open circles; new roots, open squares; old roots, filled squares. All x-axes show the time elapsed since pulse labelling (in days). Values are the mean ±SE (n=3).
Mentions: The 12C/13C isotope composition (δ13C) of OM and of respired CO2 after labelling is shown in Fig. 1. Clearly, at T0, leaves were the most labelled organs, followed by new roots (Fig. 1). Old roots showed a low degree of labelling throughout the experiment (i.e. until the end of the chase time). The kinetics were very different for leaves and roots: the δ13C value of leaves continuously declined during the chase time while that of new roots increased within 1.5 d and reached a plateau.

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