A simplified system for measuring rhizosphere respiration of fine roots in situ

In this paper, we describe a simplified system that we designed to measure rhizosphere respiration of fine roots in situ. The system consists of three major components: an air-flushing unit, a root-chamber and a CO2 sampling apparatus. We tested and measured the reliability and efficiency of the air-flushing unit while it was attached to root-chamber. The results showed that the flushing efficiencies were at least 98% when 4 l or more volume of water was used to flush the air out of both the small and medium root-chamber systems. Because the measured values of CO2-C sampled by syringe in gaseous form and measured by gas chromatograph (GC) was comparable to those sampled by NaOH solution trapping apparatus and measured by total organic C (TOC) analyzer, for simplicity we recommend the former approach. Overall, our results demonstrate that the system was reliable for measuring rhizosphere respiration of fine roots.