Phosphate Fertilization and Mycorrhizal Inoculation Increase Corn Leaf and Grain Nutrient Contents

The agricultural use of arbuscular mycorrhizal fungi, such as <i>Rhizoglomus intraradices</i>, can increase the efficiency of phosphate fertilization for the benefit of the corn plant and grain nutrition. In this study, a field experiment was conducted in an area of Selvíria/MS, Brazil, in the years 2019 and 2020, to verify the effects of reduced doses of phosphorus combined with the inoculation of corn seed with <i>R. intraradices</i> on corn plant growth and grain nutrient contents. The experiment was laid in a randomized block design in subdivided plots with four repetitions and twenty treatments resulting from combining five doses of P₂O₅ (0%, 25%, 50%, 75%, and 100% of the recommended dose) with four doses (0, 60, 120, and 180 g ha⁻¹) of an inoculant containing <i>R. intraradices</i>. Leaf and kernel macro- and micronutrient contents were evaluated. The foliar P content in 2020 was a function of the interaction between phosphate fertilization and AMF inoculation, with the highest leaf P content observed at the 100% of P₂O₅ combined with AMF inoculation between 120 and 140 g ha⁻¹. In the grains Mg content, an interaction was observed between the two factors in 2020 and the response surface, showing that the highest Mg content was obtained when maximum doses of P₂O₅ and maximum doses of inoculant were combined. A response surface showed that, in 2020, the highest leaf Zn content occurred when 35–55% P₂O₅ is applied with no inoculation and when P₂O₅ is limited to 20–30%, and there is inoculation with doses between 90 and 150 g ha⁻¹. Phosphate fertilization increased foliar K (2019) and Mg (2020) contents, with maximum points at doses of 76.57% and 88.80%, respectively.