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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is a critical nutrient for high sugarcane yields throughout its cultivation cycles, however, a higher amount of P becomes rapidly unavailable to plants due to its adsorption to soil colloids. Some plant growth-promoting bacteria (PGPBs) may be able to enhance P availability to plants and produce phytohormones that contribute to crop development, quality, and yield. Thus, this study aimed to evaluate leaf concentrations of nitrogen (N) and P, yield, and technological quality of sugarcane as a function of different levels of phosphate fertilization associated with inoculation of PGPBs. The experiment was carried out at Ilha Solteira, São Paulo—Brazil. The experimental design was randomized blocks with three replications, consisting of five phosphorus rates (0, 25, 50, 75, and 100% of the recommended P2O5 rate) and eight inoculations, involving three species of PGPBs (Azospirillum brasilense, Bacillus subtilis, and Pseudomonas fluorescens) which were applied combined or in a single application into the planting furrow of RB92579 sugarcane variety. The inoculation of B. subtilis and P. fluorescens provided a higher concentration of leaf P in sugarcane. The P2O5 rates combined with inoculation of bacteria alter technological variables and stalk yield of sugarcane. The excess and lack of phosphate fertilizer is harmful to sugarcane cultivation, regardless of the use of growth-promoting bacteria. We recommend the inoculation with A. brasilense + B. subtilis associated with 45 kg ha−1 of P2O5 aiming at greater stalk yield. This treatment also increases sugar yield, resulting in a savings of 75% of the recommended P2O5 rate, thus being a more efficient and sustainable alternative for reducing sugarcane crop production costs. [ABSTRACT FROM AUTHOR]