Uptake of ammonium and nitrate by external hyphae of arbuscular mycorrhizal fungi

A two-compartment incorporating an air-gap device technique was used to compare the uptake of NH4+-N or NO3--N by two Glomus isolates of arbuscular mycorrhizal fungi (AMF). Maize (Zea mays L.) was inoculated with G. mosseae, or G. intraradices or without. NH4+-15N or NO3--15N was supplied to the hyphae compartment 48 h before harvesting. The N uptake capability of AMF varies with fungi species and N forms supplied. The uptake and translocation of NH4+-N by AMF are higher than those of NO3--N. N uptake capability by G. intraradices is higher than that of G. mosseae, and this may be related to the growth of external hyphae of the two fungi isolates in the substrate.