Variations in δ¹³C of water–soluble leaf and phloem organic matter of Platycladus orientalis: influences of photosynthetic and post–photosynthetic fractionation

ABSTRACT

Analysis of variations in water–soluble organic matter (WSOM) δ¹³C of leaves and phloem can efficiently describe the δ¹³C distributions within plants and identify the temporal variation of δ¹³C. In this study, WSOM δ¹³C values of both leaves and phloem (twig, stem, and root) of Platycladus orientalis were measured during seven sunny days, including 2–hour interval measurements at three days for diel pattern analysis and 6–hour interval measurements at the remaining four days for day–to–day variation analysis. Analysis of WSOM δ¹³C in different plant organs showed that ¹³C was generally depleted from leaves to twigs, then enriched in stems and subsequently depleted in roots. Stems were significantly ¹³C–enriched compared to twigs (p < 0.05), while δ¹³C differences between stems and other organs and among leaves, twigs and roots were not significant (p > 0.05). No clear diel patterns in δ¹³C of leaves and phloem were found. Daily average δ¹³C values indicated that all plant organs had more positive values on sunny days during the dry season than during the wet season. Both photosynthetic and post–photosynthetic fractionation influence variations in WSOM δ¹³C. These results have implications for research on plant physiology and plant water use.

KEYWORDS:

• Carbon isotope composition
• phloem
• plant organs
• post–photosynthesis fractionation
• water–soluble organic matter

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Yonge Zhang designed and performed the experiment. Yonge Zhang analyzed the data and wrote the manuscript.

Lihua Chen, Guodong Jia and Ran Chen contributed significantly to data analysis, manuscript preparation and practice of experiment.

Xinxiao Yu revised the paper and finished the submission.

Additional information

Funding

This study was supported by the National Natural Science Foundation of China [grant number 41401013] and the Beijing Collaborative innovation center for ecoenvironmental improvement with forestry and fruit trees [grant number PXM2018_014207_000043].