New approaches to analyse allelochemicals in soil

Information on allelochemical dynamics in the rhizosphere is crucial to evaluate specific hypotheses of allelopathic effects, understanding allelopathic mechanisms and assessing the importance of allelopathic processes in plant communities. The lack of tools to obtain such information is a major barrier to investigations of allelopathy. Techniques based on various adsorbent- and sorbent-based materials are used by environmental scientists to monitor bioavailable concentrations of hydrophobic pollutants. Given the similar characteristics of many allelochemicals to these anthropogenic compounds, such methods are instructive to consider in the development of new approaches to the analysis of the rhizosphere. It has recently been demonstrated that polydimethylsiloxane (PDMS) materials including PDMS-coated stir bars, PDMS-coated optical fibers, and PDMS tubing, will recover increasing amounts of sorgoleone over time when buried beneath sorghum-sudangrass plants. These materials hold significant promise for the development of widely applicable, low-cost methods for analysis of allelochemical dynamics in the rhizosphere. Work is ongoing to optimize parameters for the use of PDMS, evaluate the potential of PDMS as a sorbent for a broad range of allelochemicals in soil, and use PDMS probes in the field.