Phosphate concentration in carrot roots colonized by <i>R</i>. <i>irregularis</i> in experiment 2 and 10 different P solubilizing bacterial strains.

<p>The distal compartment contained tri-calcium phosphate. The white bars represent the treatments where roots were colonized by AMF but no bacteria where added, and with tricalcium phosphate (Control) and no tri-calcium phosphate (NTP) in distal compartment. Error bars represent + 1 S.E. Different letters above bars represent significant differences (<i>P</i> ≤ 0.05) according to a Tukey test.</p

Photographs of bacterial colonies on the hyphae of <i>R</i>. <i>irregularis</i> in <i>in vitro</i> cultures in experiment 1.

<p>a. Growth around branching absorbing structures; b. on and around hyphae; c. around subtending hyphae of <i>R</i>. <i>irregularis</i>.</p

Growth of bacteria and growth of extraradical hyphae in Experiment 1.

<p>a. Growth of ten different P solubilizing bacteria strains on the surface of extraradical hyphae of <i>R</i>. <i>irregularis</i> growing in the distal compartment of a split <i>in vitro</i> culture in experiment 1. b. Growth of extraradical hyphae of <i>R</i>. <i>irregularis</i> in the distal compartment of a split <i>in vitro</i> culture in the presence of ten different P solubilizing bacteria strains. Measurements represent mean length per treatment per 1 cm². Error bars represent + 1 S.E. Different letters above bars represent significant differences (<i>P</i> ≤ 0.05) according to a Tukey test.</p

Mean leaf P concentration of potato plants in experiment 3.

<p>Plants were inoculated with ten different strains of P solubilizing bacteria (P28 –P108), with added inoculum of <i>R</i>. <i>irregularis</i> and insoluble P in the form of rock phosphate. AMF + Insol P = added inoculum of <i>R</i>. <i>irregularis</i> and insoluble P in the form of rock phosphate but no added bacteria. Sol P = addition of soluble P but no added bacteria or <i>R</i>. <i>irregularis</i>. Insol P = addition of insoluble P in the form of rock phosphate but no added bacteria or <i>R</i>. <i>irregularis</i>. No P = no addition of any P source and no added bacteria or <i>R</i>. <i>irregularis</i>. All plants in all treatments are planted in non-sterile soil containing an existing microbial community. Error bars represent + 1 S.E. Different letters above bars represent significant differences (<i>P</i> ≤ 0.05) according to a Tukey test.</p