Corn shoot and grain nutrient uptake affected by silicon application combined with Azospirillum brasilense inoculation and nitrogen rates

This study was developed to investigate if Ca and Mg silicate application as Si source combined with inoculation with Azospirillum brasilense and N rates can affect corn nutrient uptake. The study was set up in a Rhodic Hapludox under no-till system, located in Selvíria, state of Mato Grosso do Sul, Brazil. Treatments included: (i) two seed inoculation (with and without A. brasilense); (ii) two soil amendment sources (Ca and Mg silicate as Si source and dolomitic limestone); and (iii) five N application rates applied as side-dress (0 to 200 kg ha⁻¹). Increasing N rates positively influenced corn nutrition with increased nutrient and Si uptake in shoot and grain. The average nutrient uptake in descending order was K > N > Ca > Si > Mg > S > P >Fe > Mn > Zn > Cu > B for shoot and N > K > P > S > Mg > Ca > Si> Fe > Zn > Mn > B > Cu for grain. Calcium and Mg silicate application positively influenced corn nutrition with greater shoot P, K, Ca, S, and B uptake and grain Ca uptake. Inoculation with A. brasilense was found to increase nutrient uptake with greater shoot N, K, Ca, B, and Si and grain Cu uptake. Grain N and S increased by 22.5 and 26.8% when plants were inoculated and 200 kg N ha⁻¹ was applied and grain Zn increased by 88.6, 65.7, and 99% when plants were inoculated and 50, 150, and 200 kg N ha⁻¹ were applied, respectively. Therefore, studies conducted under tropical conditions are needed to better understand the role of Si combined with PGPB inoculation under different N management and their effects on plant nutrition and cereal development aiming at improving nutrient replenishment.