Utilization of rock phosphate in alkaline soils by plants inoculated with mycorrhizal fungi and phosphate-solubilizing bacteria

Interactions between vesicular-arbuscular (VA) mycorrhizal fungi and phosphate-solubilizing bacteria were studied in a low-phosphate alkaline soil amended with 0, 0.1% and 0.5% rock phosphate. Endogone (E3 and yellow vacuolate spore types) and two bacteria able to solubilize rock phosphate in vitro and produce plant growth regulating substances were used as inocula. Lavender (Lavandula spica var. vera L.) plants with mycorrhiza plus bacteria (either E3 plus bacteria or “yellow vacuolate” plus bacteria treatments) took up more total P than plants with either Endogone or bacteria separately at each concentration of rock phosphate. Plants not inoculated with bacteria or Endogone derived no benefit from the rock phosphate.