Impact of Clover Cyst Nematode (Heterodera Trifolii) Infection On Soil Microbial Activity in the Rhizosphere of White Clover (Trifolium Repens) - a Pulse-Labelling Experiment

White clover grown in pots of low or high fertility soil was inoculated with Heterodera trifolii, pulse-labelled with 14 C and after 14 days the distribution of 14 C was investigated. In the presence of many H. trifolii, soil fertility did not affect the root/shoot distribution of 14 C. With few H. trifolii in high-fertility soil, there was significantly less 14 C translocation to the roots. The 14 C content per pot of the microbial biomass carbon was significantly greater in those pots with many H. trifolii at both soil fertility levels. Not only was there a significant increase in the size of the microbial biomass in pots with many nematodes but also the micro-organisms had a greater 14 C concentration. This may indicate increased nutrient cycling in pots with plants infected by H. trifolii.