Field 13C Pulse Labeling of Pea, Wheat, and Vetch Plants for Subsequent Root and Shoot Decomposition Studies
Tahir, Majid Mahmood | Recous, Sylvie | Aita, Celso | Pfeifer, Ismael Cristiano | Chaves, Bruno | Giacomini, Sandro José | The University of Poonch | Fractionnement des AgroRessources et Environnement (FARE) ; Université de Reims Champagne-Ardenne (URCA)-Institut National de la Recherche Agronomique (INRA) | Universidade Federal de Santa Maria = Federal University of Santa Maria [Santa Maria, RS, Brazil] (UFSM) | ANR-13-JFAC-0001,CN-MIP,C and N Models Intercomparison and Improvement to assess management options for GHG mitigation in agrosystems worldwide(2013)
ABSTRACT: Isotopic labeling of plants is useful in tracking the fate of carbon (C) fromdifferent 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 undersubtropical field conditions for simultaneous root and shoot decomposition studies. Wheat(Triticum aestivum L.), pea (Pisum sativum L.), and vetch (Vicia sativa L.) plants weregrown inside polyvinyl chloride (PVC) cylinders and pulse labeled once a week for a totalof 11 times. After harvest, ‘’paired’’ treatments were designed by combining 13C-labeledshoots with unlabeled roots and unlabeled shoots with 13C-labeled roots, resulting in sixtreatments (2 combinations × 3 species), plus an unamended control treatment. The13C enrichment of plant parts, chemical fractions, 13C recovery, and distribution in roots,shoots, and soil were determined. Soil CO2 emissions were measured continuously by thealkaline trap method for 180 days. Plant dry matter production and chemical compositionwere not modified by 13C labeling. The maximum level of 13C enrichment (δ13C) in plantswas +495 ‰ in wheat, +426 ‰ in pea, and +378 ‰ in vetch plants. All three cropsshowed 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 theroots, and 2.7 to 4.3 % was in the soil. The rate of C mineralization and cumulative Cmineralization were not different between ‘’paired’’ treatments of the three crops, showingthat the paired treatments were equally degradable. The pulse-labeling technique usedunder field conditions allowed for production of sufficiently labeled wheat, pea, and vetchplants. Therefore, it is a practical approach with respect to resource demand (tracer andlabor costs), and it is suitable for in situ labeling.
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