Field 13C Pulse Labeling of Pea, Wheat, and Vetch Plants for Subsequent Root and Shoot Decomposition Studies
Résumé
ABSTRACT: Isotopic labeling of plants is useful in tracking the fate of carbon (C) from
different plant parts in a soil-plant system when these parts decompose simultaneously.
Pulse labeling is a relatively simple technique and is amenable for use in the field.
Therefore, we evaluated a 13CO2 pulse-labeling method to label crop plants under
subtropical field conditions for simultaneous root and shoot decomposition studies. Wheat
(Triticum aestivum L.), pea (Pisum sativum L.), and vetch (Vicia sativa L.) plants were
grown inside polyvinyl chloride (PVC) cylinders and pulse labeled once a week for a total
of 11 times. After harvest, ‘’paired’’ treatments were designed by combining 13C-labeled
shoots with unlabeled roots and unlabeled shoots with 13C-labeled roots, resulting in six
treatments (2 combinations × 3 species), plus an unamended control treatment. The
13C enrichment of plant parts, chemical fractions, 13C recovery, and distribution in roots,
shoots, and soil were determined. Soil CO2 emissions were measured continuously by the
alkaline trap method for 180 days. Plant dry matter production and chemical composition
were not modified by 13C labeling. The maximum level of 13C enrichment (δ13C) in plants
was +495 ‰ in wheat, +426 ‰ in pea, and +378 ‰ in vetch plants. All three crops
showed similar patterns of 13C distribution in the following order: shoots > roots > soil.
On average, 81 to 89 % of the recovered 13C was in the shoots, 7 to 14 % was in the
roots, and 2.7 to 4.3 % was in the soil. The rate of C mineralization and cumulative C
mineralization were not different between ‘’paired’’ treatments of the three crops, showing
that the paired treatments were equally degradable. The pulse-labeling technique used
under field conditions allowed for production of sufficiently labeled wheat, pea, and vetch
plants. Therefore, it is a practical approach with respect to resource demand (tracer and
labor costs), and it is suitable for in situ labeling.
Domaines
Milieux et Changements globauxOrigine | Accord explicite pour ce dépôt |
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