Phytate utilization of maize mediated by different nitrogen forms in a plant–arbuscular mycorrhizal fungus–phosphate-solubilizing bacterium system

Abstract

<div><p>A pot experiment was conducted to investigate the organic phosphorus (P) (phytate) utilization of <i>Zea mays</i> L. with different nitrogen (N) forms (NH₄⁺ and NO₃⁻) when both arbuscular mycorrhizal (AM) fungus (<i>Funelliformis mosseae</i>) and phosphate-solubilizing bacterium (PSB, <i>Pseudomonas alcaligenes</i>) are present. The soil was supplied with either KNO₃ or (NH₄)₂SO₄ (200 mg kg⁻¹ N) with or without phytin (75 mg P kg⁻¹). Results showed that the application of NH₄⁺ to the soil in a plant–AM fungus–PSB system decreased rhizosphere pH and increased phosphatase activity. It also enhanced the mineralization rate of phytin, which resulted in the release of more inorganic P. The application of NO₃⁻ promoted mycorrhizal colonization and hyphal length density in the soil. The inorganic P in the hyphosphere decreased, but more P was transferred to the plant through the mycorrhizal hyphae. Hence, in addition, the application of the two different N forms did not significantly alter the content of plant P. The plant supplied with different N fertilizers acquired P through different mechanisms associated with other microbes. NH₄⁺ application promoted phytin mineralization by decreasing soil pH, whereas NO₃⁻ application increased inorganic P uptake by strengthening the mycorrhizal pathway.</p></div