Interactive effect of silicon application and Azospirillum brasilense inoculation on wheat nutrient uptake and accumulation combined with N application rates

This study was developed to investigate the interactive effect of silicon (Si) application and the inoculation of plant growth promoting bacteria (PGPB) Azospirillum brasilense on wheat nutrient uptake and accumulation on biomass and grains when combined with nitrogen (N) application rates. The study was set up in a Rhodic Hapludox under no-till system, located in Selvíria, state of Mato Grosso do Sul, Brazil (tropical Savannah region). Treatments were tested in a randomized complete block design with four replicates, arranged in a full factorial design 2 × 2 × 5 and included: i) two soil amendment sources (Ca and Mg silicate as Si source and dolomitic limestone); ii) two seed inoculation (with and without A. brasilense) and iii) five N application rates applied as side-dress (0, 50, 100, 150 and 200 kg ha⁻¹). Increasing N application rates positively influenced wheat nutrition with increased nutrient and Si uptake in shoot. Calcium and Mg silicate positively influenced wheat nutrition with greater shoot Si and grain N, P, K, B, Cu, Fe, Mn, Zn and Si uptake. In addition, Si was the third and sixth element most absorbed in wheat shoot and grain respectively. Inoculation with A. brasilense was found to increase nutrient uptake with greater shoot K and S and grain N, P, K, Mg, S, B, Cu, Mn, Zn and Si uptake. Azospirillum brasilense inoculation provided greater N uptake, with an increase of 5.8 and 8.9% on shoot and grain uptake.