Microbial Competition for Glucose in Excised Root Experiments

Competition was determined by measuring 14 CO 2 evolution from the metabolism of 14 C‐glucose by sterile roots or by roots with microflora present. Test solutions consisted of sterile 10 ‐4 M CaSO 4 containing 1 µCi 14 C‐glucose. A new technique was used to measure 14 CO 2 . This technique does not rely on any wet chemical treatment and each analysis is completed in 72 sec. Treatments included sterile roots, nonsterile roots, and the microbial flora without roots. Sterile roots produced a low amount of 14 CO 2 from the 14 C‐glucose. The nonsterile roots rapidly produced a copious amount of 14 CO 2 . The low microbial inoculum without root material was dormant and did not produce any 14 CO 2 . Apparently the microflora normally present during excised root experiments successfully competes with the root for glucose thus masking uptake attributable to the root.