Effects of sheared-root inoculurn of Glomus intraradices on wheat grown at different phosphorus levels in the field

Growth and yield potential of wheat inoculated with the arbuscular mycorrhizal fungus Glomus intraradices were investigated at different phosphorus levels under field conditions. Surface sterilized wheat (Triticum aestivum var. Swift) was infected with sheared-root inoculum at the rate of 0.5 g dry weight per 1000 seed and sown in P-deficient loamy and slightly acidic (pH 5.5) field plots fertilized with 0, 5, 10 and 20 kg ha(-1) of commercial P. Plants inoculated had significantly higher dry weight and yield compared to controls. Mycorrhization of roots in both inoculated and control plants increased with P-level but decreased over time at higher P-levels. The mycorrhiza-mediated growth effect was higher at 5 and 10 kg than at 20 kg P ha(-1) in terms of plant dry weight, number of grain per spike, and 1000 grain weight. It is suggested that sheared-root inoculum of G. intraradices may contribute to reducing P fertilizer applications. (C) 2003 Elsevier B.V. All rights reserved.