Factors affecting arbuscular mycorrhizal dependency of wheat genotypes with different phosphorus efficiencies

Three wheat (Triticum aestivum L.) genotypes with high, intermediate and low phosphorus (P) efficiency were grown in a pot experiment with low P supply and adequate P supply either inoculated with the arbuscular mycorrhizal fungus Glomus versiforme or uninoculated. The mycorrhizal dependency of the genotype with relatively high P efficiency was lower than that of the genotypes with lower P efficiencies. Linear correlation analysis revealed that mycorrhizal dependency was primarily controlled by P uptake efficiency. More carbohydrate was translocated to the roots of genotypes with low P efficiency than of those with high P efficiency. In a second pot experiment the same three genotypes were grown in low P soils. Higher hyphal length density arising from carbohydrate translocation led to more P uptake, and this may account for higher mycorrhizal dependency.