Corn Yield and Foliar Diagnosis Affected by Nitrogen Fertilization and Inoculation with Azospirillum brasilense

Inoculation With Growth-Promoting Bacteria Azospirillum brasilense and Its Effects on Productivity and Nutritional Accumulation of Wheat Cultivars

Agricultural practices that allow a productive increase in a sustainable manner are becoming increasingly necessary to feed an ever-growing global population. The inoculation with Azospirillum brasilense has the potential to reduce the use of synthetic mineral fertilizers with efficient capacity to promote plant growth and increase nutrition. Therefore, this research was developed to investigate the potential use of A. brasilense to increase the accumulation of macro- and micronutrients and its influence on grain yield, plant height, and spike population in two wheat cultivars (CD1104 and CD150), under irrigated conditions in the Brazilian Cerrado. The study was carried out in a Rhodic Hapludox under a no-tillage system. The experiment was designed in randomized blocks with six replications, arranged in a 2 × 2 factorial scheme: two cultivars (CD150 and CD1104) and two levels of inoculation (control and with A. brasilense). The inoculation with A. brasilense provided greater accumulation of micronutrients in the aerial part of the wheat. In the cultivar CD1104, B and Cu had an accumulation 27.7 and 57.4% higher compared with those of the control without bacteria. In the cultivar CD150, Azospirillum increased the accumulation of B, Fe, and Mn by 43.8, 49.9, and 22%, respectively, and reduced Cu by 21.9%, compared with those of the control. The cultivar CD150 has greater efficiency to accumulate N (+35.5 kg N ha−1) as compared with the cultivar CD1104. Interactions between inoculation and cultivars resulted in greater accumulation of S and K in the shoot of the wheat cultivar CD150, as well greater accumulation of Cu in CD1104. In growth assessments, inoculation or cultivars did not statistically influence wheat grain yield and spike population. Howevere, for plant height, the CD1104 genotype has 13.1% bigger plant height on average than that of the CD150 genotype. Inoculation can contribute more sustainably to wheat nutrition.

Successive sewage sludge fertilization: Recycling for sustainable agriculture

Sewage sludge (SS) is widely used in agriculture in several countries around the world. However, the impact of successive applications of SS on soil and the risks of nutrient leaching are often neglected. In this study, corn was grown on a constructed wetland for four crop cycles (two years), in which the wetland was subjected to successive SS applications. The objective of this study was to evaluate how the successive applications of SS affect the availability and leaching of nutrients in the soil profile, after two years of cultivation. Experiments were performed using a randomized block design with repeated measurements in time, that is, soil was sampled in each harvest. Six treatments were tested: four fertilizations based on sewage sludge, resulting from biological and anaerobic treatment, calculated to provide 25 (SS25), 50 (SS50), 75 (SS75), and 100% (SS100), of the N required for corn production (140 kg ha^-1); a mineral fertilization (NPK) (140 kg ha^-1 N, 70 kg ha^-1 of P₂O₅ and 40 kg ha^-1 of K₂O) and a control (without fertilization). The results showed that four consecutive applications of SS100 for two years caused significant accumulation of nutrients and organic matter in the superficial layers of the soil. The electrical conductivity and the concentration of NO₃^- in the soil solution were higher than those permitted by Brazilian legislation. The adoption of domestic SS in Brazilian agriculture can be a viable alternative in the search for an environment-friendly and economically feasible method for SS disposal.

Influence of Azospirillum brasilense associated with silicon and nitrogen fertilization on macronutrient contents in corn

Information regarding the interaction between biological nitrogen fixation (BNF) with Azospirillum brasilense inoculation and the use of silicon (Si) is needed. Silicon exerts numerous benefits on grasses, especially when the plants are subjected to biotic and abiotic stresses, affecting plant nutrition. The aim of this research was to determine if there is a synergistic effect between the inoculation with A. brasilense and Si use, on macro-nutrient content in corn shoot and root. The field trial was performed in Selvíria, Brazil, on a Typic Rhodic Hapludox soil under no-till system. The experimental design was a completely randomized block design with four replicates arranged in a 2 × 5 × 2 triple factorial arrangement, consisting of two soil acidity corrective sources (dolomitic limestone and Ca and Mg silicate as sources of Si); five N doses (0, 50, 100, 150 and 200 kg ha-1 applied in topdressing); with and without seed inoculation with A. brasilense. The inoculation favored N concentration in shoots and increased the N and S concentration even when associated to high N rates in topdressing. The Si as Ca and Mg silicate associated with the increment of N rates does not promote an increase in the macronutrients uptake. Although it did not favor the N use, the Si also did not negatively affect the benefits of the A. brasilense.

Inoculation of Azospirillum brasilense associated with silicon as a liming source to improve nitrogen fertilization in wheat crops

This research was developed to investigate whether inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in wheat and to evaluate and correlate nutritional and productive components and wheat grain yield. The study was carried out on a Rhodic Hapludox under a no-till system with a completely randomized block design with four replications in a 2 × 2 × 5 factorial scheme: two liming sources (with Ca and Mg silicate as the Si source and limestone); two inoculations (control - without inoculation and seed inoculation with A. brasilense) and five side-dress N rates (0, 50, 100, 150 and 200 kg ha-1). The results of this study showed positive improvements in wheat growth production parameters, NUE and grain yield as a function of inoculation associated with N rates. Inoculation can complement and optimize N fertilization, even with high N application rates. The potential benefits of Si use were less evident; however, the use of Si can favour N absorption, even when associated with A. brasilense. Therefore, studies conducted under tropical conditions with Ca and Mg silicate are necessary to better understand the role of Si applied alone or in combination with growth-promoting bacteria such as A. brasilense.

Can silicon applied to correct soil acidity in combination with Azospirillum brasilense inoculation improve nitrogen use efficiency in maize?

Alternative management practices are needed to minimize the need for chemical fertilizer use in non-leguminous cropping systems. The use of biological agents that can fix atmospheric N has shown potential to improve nutrient availability in grass crops. This research was developed to investigate if inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in maize. The study was set up in a Rhodic Hapludox under a no-till system, in a completely randomized block design with four replicates. Treatments were tested in a full factorial design and included: i) five side dress N rates (0 to 200 kg ha-1); ii) two liming sources (Ca and Mg silicate and dolomitic limestone); and iii) with and without seed inoculation with A. brasilense. Inoculation with A. brasilense was found to increase grain yield by 15% when N was omitted and up to 10% when N was applied. Inoculation also increased N accumulation in plant tissue. Inoculation and limestone application were found to increase leaf chlorophyll index, number of grains per ear, harvest index, and NUE. Inoculation increased harvest index and NUE by 9.5 and 19.3%, respectively, compared with non-inoculated plots. Silicon application increased leaf chlorophyll index and N-leaf concentration. The combination of Si and inoculation provided greater Si-shoot accumulation. This study showed positive improvements in maize growth production parameters as a result of inoculation, but the potential benefits of Si use were less evident. Further research should be conducted under growing conditions that provide some level of biotic or abiotic stress to study the true potential of Si application.

Assessing Forms of Application of Azospirillum brasilense Associated with Silicon Use on Wheat

The use of biological techniques such as plant growth-promoting bacteria (PGPB) can represent a sustainable alternative for cereal growth in tropical areas. Research showing the potential for management practices which optimize PGPB inoculation is of utmost importance. This research was developed to investigate the potential use of Azospirillum brasilense in wheat cropping systems, as well as to assess the potential synergistic interactions between the beneficial use of silicon (Si), principally under abiotic and biotic conditions, and A. brasilense forms of application and how they impact crop development and wheat yield. The study was set up in a Rhodic Hapludox under a no-till system. The experimental design was a completely randomized block design with four replicates arranged in a factorial scheme with four inoculation forms (control, seed, groove, and leaf) and two soil acidity corrective sources (Ca and Mg silicate as Si source and dolomitic limestone). Seed inoculation was more effective in promoting wheat growth and development, with higher yield, showing an increase of 26.7% in wheat grain yield. Calcium and magnesium silicate application associated with foliar inoculation and without A. brasilense inoculation can increase wheat grain yield.

Nutritional assessment and yield of corn as a function of boron rates and zinc fertilization

Brazilian Cerrado soils are commonly deficient in boron (B) and zinc (Zn). It is still debated whether B and Zn interaction has a synergistic or antagonistic effect on the absorption thereof. Thus, we conducted this study to evaluate the effect of boron rates (0, 1, 2, 3, and 4 kg ha?1, as boric acid), with or without zinc fertilization (2 kg ha?1 Zn, as zinc sulfate), on corn nutritional status and grain yield. We also assessed the residual effect of such fertilization on the fall corn crop grown on an Oxisol in a no-tillage system. A synergistic effect between B and Zn was observed on corn nutritional status when applied to the soil at rates of up to 2 kg ha?1, with higher soil contents resulting from the interaction between these micronutrients. Zinc fertilization and increasing boron rates had no significant influence on corn grain yield in both spring/summer and fall crops, grown on a boron-deficient, clayey soil of Cerrado biome.

Does the nitrogen application associated with Azospirillum brasilense inoculation influence corn nutrition and yield?

ABSTRACT The aim of this study was to investigate the synergistic effect between inoculation with Azospirillum brasilense and nitrogen application, thus enabling a higher efficiency of nitrogen fertilization, as evaluated by nutritional value, components production, and grain yield of irrigated corn. The experiment was conducted in Selvíria, MS, Brazil, under a no-till system, on an Oxisol in the Brazilian Cerrado. The experiment was set up in a randomized block design with four replications, in a 4 × 2 factorial arrangement: four patterns of nitrogen application [application of 30 kg ha-1 of N at sowing and 150 kg ha-1 as cover (30 + 150); 30 kg ha-1 of N at sowing, split into two applications of 75 kg ha-1 as cover (30 + 75 + 75); 180 kg ha-1 of N at sowing (180); and 150 kg ha-1 of N at sowing and 30 kg ha-1 as cover (150 + 30)]; with and without inoculation of the seeds with A. brasilense. The application of 30 kg ha-1 of N at sowing and a single application of 150 kg ha-1 or two applications of 75 kg ha-1 in topdressing, inoculated with Azospirillum brasilense provided better nutrition and development, with a positive reflection on irrigated corn grain yield in the Brazilian Cerrado.

Nitrogen rates associated with the inoculation of Azospirillum brasilense and application of Si: Effects on micronutrients and silicon concentration in irrigated corn

The aim of this study was to analyze whether there are differences between the inoculation with Azospirillum brasilense and the silicon application, thus enabling a higher efficiency of nitrogen fertilization, evaluating micronutrients and silicon concentration in shoots and roots of irrigated corn (Zea mays). The experiment was conducted in Selviria, Brazil, under a no-till system, on a Typic Rhodic Hapludox. The experiment was set up as a randomized block design with four replications, in a 2 × 5 × 2 factorial arrangement consisting of two soil corrective sources (dolomitic limestone and Ca and Mg silicate as source of Si); five N rates (0, 50, 100, 150 and 200 kg ha-1); with and without inoculation with A. brasilense. N rates increased B, Cu and Fe concentrations in shoots and B, Cu, Fe, Mn, Zn and Si in roots. Inoculation provided greater concentrations of B and Fe in shoots, and B in roots. Although inoculation with A. brasilense favored micronutrient uptake, it negatively affected Si concentration in shoots in 2015/16 crop. The use of Si in the form of Ca and Mg silicate promotes an increase in Mn, Si and Zn uptake in shoots and Mn and Si concentration in roots.

Do the application forms and doses of boron affect wheat crops?

ABSTRACT Boron is one of the most limiting micronutrients in the grain production system in Brazil. Thus, the objective of this study was to evaluate the effects of the application forms and doses of boron on the concentration of this nutrient in the leaves, straw, and grains of wheat, as well as the production components and grain yield. The residual effect of boron in the soil was also evaluated. An experiment was conducted in a no-tillage system in Oxisol with clay texture in Selvíria, Mato Grosso do Sul. The experimental design was a randomized block design with four replicates arranged in a 4 x 3 factorial scheme. Four doses of boron (0, 1, 2, and 4 kg ha-1) were applied with a boric acid source (B = 17%) and three application forms: a) during the desiccation of the predecessor straw with herbicide; b) at the time of sowing in soil along with formulated fertilization seeding, and c) via the leaves with the application of post-emergent herbicide. The application of boron to the soil at the time of sowing at an approximate dose of 2 kg ha-1 provides the highest number of spikelets per ear and wheat grain yield.

AZOSPIRILLUM BRASILENSE VIA FOLIAR E DOSES DE NITROGÊNIO EM COBERTURA NA CULTURA DO TRIGO NA REGIÃO DE ITAPEVA-SP

A utilização de bactérias diazotróficas na agricultura, especialmente em gramíneas, tem por finalidade incrementar a produção e produtividade aliando com menor dose ou supressão das fontes nitrogenadas aplicadas para fertilização do solo. Diante disso, o trabalho objetivou avaliar a viabilidade da inoculação de Azospirillum brasilense via foliar com doses de nitrogênio em cobertura na produção e produtividade do trigo. O experimento foi implantado na Fazenda Bom Viver, Bairro dos Prestes em Itapeva-SP, na safra de 2016, sendo realizado em plantio direto (SPC) em área de sucessão soja e milho safrinha. Os tratamentos foram em esquema fatorial 2x4 em blocos ao acaso (DBC) sendo aplicado a formulação liquida de Azospirillum brasiliense (AbV5 com 2x108 células viáveis mL-1) na dose de 0,5 L.ha-1 via foliar e sem aplicação e posterior adubação nitrogenada com 0; 30; 60 e 90 kg.ha-1 em cobertura. Tanto a aplicação foliar de Azospirillum como a cobertura de N, foram aplicadas após 30 dias da semeadura (30 DAS). A variedade de trigo utilizada no plantio foi o Sinuelo, com manejo adotado pelo proprietário da área com aplicação de regulador de crescimento. Foram realizadas as avaliações a campo das plantas, medindo-se: a altura das plantas; espigas por metro linear; número de grãos por espiguetas; peso hectolítro; massa de mil grãos e produtividade. Pelos resultados obtidos, houve maior altura de plantas com o aumento das doses de nitrogênio em cobertura. A inoculação de Azospirillum brasiliense via foliar não mostrou interação entre as doses de nitrogênio em cobertura, não havendo estatisticamente incremento nos componentes de produtividade do trigo.

Modes of application of cobalt, molybdenum and Azospirillum brasilense on soybean yield and profitability

ABSTRACT The use of cobalt (Co) and molybdenum (Mo) along with the co-inoculation with Azospirillum brasilense on soybean can contribute to biological nitrogen fixation (BNF), allowing higher yields. Thus, this work aimed to study the technical and economic viability of soybean in the Cerrado, according to the mode of application of Co + Mo, and seed or leaf co-inoculation with Azospirillum brasilense. The experiment was conducted in Selvíria-MS, in a no-tillage system in an Oxisol, arranged in a randomized block design with six treatments (seed application of two treatments with Co + Mo, with or without inoculation with A. brasilense, respectively; Foliar application of Co + Mo at soybean V3 stage; Foliar application of Co + Mo together with A. brasilense at V3 growth stage; Foliar application of A. brasilense at V3 growth stage; and the Control, consisting of only inoculation with Rhizobium), and four replicates. Seed application of Co + Mo associated with seed inoculation with A. brasilense promoted the highest leaf N content, hundred-grain weight, yield and profitability with the soybean crop.