Plant Growth Responses to Vesicular‐arbuscular Mycorrhiza Xii. Field Inoculation Responses of Barley at Two Soil P Levels

SUMMARY The results are described of a field experiment in which barley was inoculated in the field by‐placing 20 g of soil containing infected roots below each sowing position. Three VA endophytes were used as inoculants and half the plots were given phosphate before sowing. Growth and infection were recorded twice during the experiment and at harvest. In the plots without added phosphate the fresh wt of ears was doubled by inoculation to approximately 100 gm‐2irrespective of endophytes. Added phosphate increased this more than inoculation and weight of ears rose to 200 to 300 gm‐2. With one inoculant dry wt of ears was 35% greater than with phosphate only, but with the other two it was marginally less. The results are discussed in relation to other experiments with barley and to the levels of infection throughout the experiment.