Effects of vesicular-arbuscular mycorrhizal inoculation on the yield and phosphorus uptake of field-grown barley

In a field experiment on barley, the effects of soil application of phospho rus fertilizer and inoculum of Glomus mosseae on the mycorrhizal colonizati on of roots, crop yield and P uptake were evaluated in a natural or methyl bromide fumigated soil. Soil fumigation raised the amount of available nitr ogen (NH4-N+NO3-N) in the soil by 13 mg kg(-1). Although both soils were eq ualized for the N status by adding N fertilizer to non-fumigated soil, fumi gated soil gave higher crop yield. The applied P increased the dry matter y ield significantly but suppressed mycorrhizal infection. An overall small i ncrease of 3% in total P uptake and a decrease of up to 2% in grain and str aw yield were observed as a result of inoculation, which were statistically non-significant at P < 0.05. These trends in results were most likely due to the status of available soil P higher than the threshold limit for a pos itive mycorrhizal growth response. (C) 2000 Elsevier Science Ltd. All right s reserved.