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Volatile organic compounds in the roots and rhizosphere of Pinus spp.

Lin, Chun and Owen, Susan M. and Peñuelas, Josep (2007) Volatile organic compounds in the roots and rhizosphere of Pinus spp. Soil Biology and Biochemistry, 39 (4). pp. 951-960. ISSN 0038-0717

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Abstract

Plant roots normally release a complex mixture of chemicals which have important effects in the rhizosphere. Among these different root-emitted compounds, volatile isoprenoids have received very little attention, yet they may play important and diverse roles in the rhizosphere, contributing to the regulation of microbial activity and nutrient availability. It is therefore important to estimate their abundance in the rhizosphere, but so far, there is no reliable sampling method that can be used to measure realistic rates of root emissions from plants growing in field conditions, or even in pots. Here, we measured root content of volatile isoprenoids (specifically monoterpenes) for Pinus pinea, and explored the feasibility of using a dynamic bag enclosure method to measure emissions from roots of intact pot-grown plants with different degrees of root cleaning. We also investigated a passive diffusion method for exploring monoterpenes in soil at incremental distances from mature Pinus sylvestris trees growing in field conditions. Total monoterpene content of P. pinea roots was 415±50 μg g−1 fresh wt in an initial screening study, and between 688±103 and 1144±208 μg g−1 dry wt in subsequent investigations. Emissions from shaken-clean roots of intact plants and roots of intact plants washed to remove remaining soil after shaken-clean experiments were 119±14 and 26±5 μg g−1 dry wt h−1, respectively. Emissions from intact roots in soil-balls were an order of magnitude lower than from shaken-clean roots, and probably reflected the amount of emitted compounds taken up by physical, chemical or biological processes in the soil matrix surrounding the roots. Although monoterpene content was not significantly different in droughted roots, emission rates from droughted roots were generally significantly lower than from well-watered roots. Finally, passive sampling of monoterpenes in the soil at different distances from mature P. sylvestris trees in field conditions showed significantly decreasing sampling rates with increasing distance from the trunk. We conclude that it is feasible to measure volatile isoprenoid emissions from roots but the method of root preparation affects magnitude of measured emissions and therefore must be decided according to the application. We also conclude that the rhizosphere of Pinus species is a strong and previously un-characterized source of volatile isoprenoid emissions and these are likely to impact significantly on rhizosphere function.

Item Type: Article
Journal or Publication Title: Soil Biology and Biochemistry
Uncontrolled Keywords: Volatile isoprenoids ; VOCs ; Monoterpenes ; Sesquiterpenes ; Rhizosphere ; Roots ; Solvent extraction ; Dynamic head-space sampling ; Passive sampling ; Root emission ; Pinus spp.
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 31420
Deposited By: Mr Richard Ingham
Deposited On: 15 Jan 2010 14:21
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 16:57
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/31420

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