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Repeat‐pulse 13 CO 2 labeling of canola and field pea: implications for soil organic matter studies
Author(s) -
Sangster Amy,
Knight Diane,
Farrell Richard,
BedardHaughn Angela
Publication year - 2010
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4699
Subject(s) - canola , chemistry , point of delivery , residue (chemistry) , crop residue , agronomy , decomposition , tracer , horticulture , food science , agriculture , biology , ecology , biochemistry , organic chemistry , physics , nuclear physics
Both the quantity and quality of plant residues can impact soil properties and processes. Isotopic tracers can be used to trace plant residue decomposition if the tracer is homogeneously distributed throughout the plant. Continuous labeling will homogeneously label plants but is not widely accessible because elaborate equipment is needed. In order to determine if the more accessible repeat‐pulse labeling method could be used to trace plant residue decomposition, this labeling procedure was employed using 13 CO 2 to enrich field pea and canola plants in a controlled environment. Plants were exposed weekly to pulses of 33 atom% 13 CO 2 and grown to maturity. The distribution of the label throughout the plant parts (roots, stem, leaves, and pod) and biochemical fractions (ADF and ADL) was determined. The label was not homogeneously distributed throughout the plant; in particular, the pod fractions were less enriched than other fractions indicating the importance of continuing labeling well into plant maturity for pod‐producing plants. The ADL fraction was also less enriched than the ADF fraction. Because of the heterogeneity of the label throughout the plant, caution should be applied when using the repeat‐pulse method to trace the fate of 13 C‐labeled residues in the soil. However, root contributions to below‐ground C were successfully determined from the repeat‐pulse labeled root material, as was 13 C enrichment of soil within the top 15 cm. Canola contributed more above‐ and below‐ground residue C than field pea; however, canola was also higher in ADF and ADL fractions indicating a more recalcitrant residue. Copyright © 2010 John Wiley & Sons, Ltd.