A quick and simple spectrophotometric method to determine total carbon concentrations in root exudation samples

Abstract PurposeRoot exudates are key components driving belowground interaction between plant, microbes and soil. While high-end analytical approaches provide advanced insights into exudate metabolite diversity, the amount of total carbon (C) released by roots is the most basic parameter that should always be measured when characterizing root exudation as it (i) provides quantitative information of C exuded into the surrounding soil and (ii) allows to relate the abundance of individual exudate compounds to total C released. Here we propose a simple and quick, spectrophotometry-based method to quantify total dissolved organic carbon (DOC) concentration in exudation samples that is based on measuring the absorption of a pre-filtered but otherwise untreated exudate sample at 260 nm.MethodExudate samples collected from different species and experimental approaches were analysed with our DOC assay and results were compared with C concentrations obtained by liquid TOC-analyser, demonstrating the suitability of our method.ConclusionOur method will facilitate quick and inexpensive measurements and thus increase our understanding of root exudation and related rhizosphere processes.