Analysis of the phenolic compounds in root exudates produced by a subalpine coniferous species as responses to experimental warming and nitrogen fertilisation

Abstract

In terrestrial ecosystems, plant root exudates clearly play a crucial role in the belowground ecosystem. However, there have been few reports on root exudates from field-grown plants or mature trees in situ, especially when exposed to experimental warming. In this study, we adopted and modified a culture-based cuvette system developed especially for root exudation collection in the field to collect soluble root exudates of a subalpine coniferous species, Abies faxoniana, under experimental warming and nitrogen fertilisation treatments. We then analysed the chemical composition and relative abundance of root exudates using gas chromatography-mass spectrometry (GC-MS). The major chemical constituents of root exudates were phenols and their derivatives of all the different treatments, such as 2,6-di-tert-butyl-4-methylphenol. Experimental warming had significant effects on the relative contents of major compounds and an increase effect on the total phenolic acid compounds. By contrast, there were small significant effects of N fertilisation on root exudation and no significant effects of the warming×N fertilisation interaction. Meanwhile, warming also markedly increased soil polyphenol oxidase activity and it may be soil ecological adjustment response to changes of root exudation under global climate warming.

Keywords:

• analysis
• root exudates
• phenols
• warming
• subalpine coniferous species

Acknowledgements

We thank the staff in the Maoxian Mountain Ecosystem of CERN Research Station for their kind help with field investigations.

Funding

This study was supported jointly by the National Natural Science Foundation of China (No. 31270552), the strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA01050303) and the National Key Technology R & D Program (No. 2011BAC09B04).

Supplemental data

Supplemental data for this article can be accessed here. [10.1080/02757540.2013.868891]