DSpace Collection:

Otimização do depósito de pulverização no cafeeiro sob diferentes condições operacionais

2026-07-23T06:22:26Z

Title: Otimização do depósito de pulverização no cafeeiro sob diferentes condições operacionais Abstract: Air-assisted spraying is widely used in the phytosanitary management of coffee (Coffea arabica L.), but it faces significant limitations. The complex architecture of the plant, the variability in the orientation of branches and leaves, and the dependence on airflow make precise and uniform droplet distribution difficult, potentially compromising the effectiveness of phytosanitary control and generating environmental impacts. Air-assisted spraying deposits part of the droplets in the target application area (reference fraction), while another part passes through the canopy, propelled by the airflow (pass-through fraction). In this context, deepening the knowledge about droplet deposition in tree crops, through the analysis of scientific production and understanding how operational parameters influence deposition, in fractions of the sprayed area and along the canopy, becomes essential to support future studies and the development of more effective and sustainable spraying strategies. Therefore, this work aimed to: (i) to analyze the scientific production on spray deposition in perennial crops using scientometrics; (ii) to determine the deposit in the fractions of the sprayed area using an air-assisted sprayer, considering different application rates and nozzle types; and (iii) to determine the deposit in the fractions of the sprayed area, especially on leaf surfaces (adaxial and abaxial) of coffee plants, under different spray angles on different sides of the application row. The analysis of scientific production was conducted using scientometrics, with the aid of Bibliometrix and VOSviewer software. The Web of Science database was used to search for documents, with prior definition of keywords and application of filters. The retrieved records were exported with complete information and subjected to quantitative analyses, such as number of publications per year, most productive journals, most frequent authors and institutions, number of citations, as well as keywords and co-authorship networks. To determine the deposition in fractions of the sprayed area, both field experiments adopted a 3 x 2 factorial design. In the first trial, the factors were three application rates (200, 400, 600 L ha-1) and two spray nozzle types (hollow cone and flat fan), with four replications. The deposition was quantified on two application sides (left and right of the application row), three thirds of the plant (upper, middle, and lower), and two positions of the plagiotropic branch (inner and outer). In the second trial, the factors were three different spray jet angles (varying angles along the branch 40º-60º-90º, fixed angles of 80º and 90º) and two application sides (left and right of the application row). Deposition was quantified on the three thirds of the plant (upper, middle, and lower) and on the abaxial and adaxial leaf surfaces. The deposition was determined by adding a tracer to the spray solution, with readings taken by spectrophotometry. Measurements on application sides, plant thirds, and branch positions were nested. Due to the experimental complexity, the data were analyzed using linear mixed models, with mean comparisons using Tukey's test (p < 0.05) in RStudio software. The scientometric analysis revealed a growth in studies on deposition in tree crops; however, gaps remain regarding evaluation on natural targets and leaf surfaces, as well as the need for intelligent technologies to optimize spraying in these crops. Deposition tests in fractions of the sprayed area showed that, at an application rate of 200 L ha-1, the hollow cone nozzle provided greater deposition in the reference fraction and reduced deposition in the overlap fraction, while the flat fan nozzle increased deposition in the overlap fraction, indicating greater spray passage through the canopy. A 90º spray angle provided greater deposition and better uniformity, but increased losses due to overlap. In contrast, an 80º angle demonstrated greater retention of the spray solution in the target area, although with reduced uniformity. The combination of angles (40º-90º-60º), although more heterogeneous, showed an alternative for vertically directed applications. The abaxial surface of the leaf receives greater droplet deposition in the upper third of the plant, while on the adaxial surface greater deposition occurs in the lower third. The greater accumulation of droplets in internal positions and the differences between application sides highlight the influence of plant architecture and airflow asymmetry on the spatial distribution of droplets. It is estimated that between 20 and 30% of the tracer exceeded the target area, resulting in losses due to overlap. These results indicate the need to optimize operational parameters and spray direction to increase efficiency and reduce product losses in phytosanitary management.

Adubação mineral e organomineral: incubação em solos contrastantes e respostas do cafeeiro

2026-07-22T06:28:23Z

Title: Adubação mineral e organomineral: incubação em solos contrastantes e respostas do cafeeiro Abstract: This thesis comprises a review and two experimental studies on nutrient management in Coffea arabica L., relating soil processes, plant growth, enzymatic activity, and yield. The review addresses nutrient functions, constraints imposed by acidity, texture, and cation exchange capacity, and redox markers, with emphasis on hydrogen peroxide (H₂O₂), lipid peroxidation (PL), and antioxidant enzymes. In the incubation assay, one powdered mineral fertilizer (M.f.) and two poultry-litter organominerals, one powdered (OM.f.) and one pelletized (OM.p.), were applied to sandy and clayey soils and evaluated at 15, 90, and 150 days. In the initial phase, soil type was the main factor affecting pH, exchangeable bases, and acidity. In the final phase, the interaction between source and texture became more evident, with greater P and K persistence in the sandy soil under organominerals and improvement of acidity-related attributes in the clayey soil, mainly under the powdered formulation. In the field experiment, three sources, one conventional mineral fertilizer, one poultry-manure organomineral (OMef), and one filter-cake organomineral (OMtf), were combined with four rates of an organic compound based on poultry waste. These sources altered soil chemical attributes, modified plant growth, adjusted the antioxidant system, and increased first-harvest yield. OMef promoted greater initial availability of P and exchangeable bases, whereas OMtf increased stem diameter and the emission of plagiotropic branches. Rates between 4 and 6 t ha⁻¹ strengthened antioxidant activity, and yield increased linearly, with an estimated gain of 308.3 kg ha⁻¹ of coffee beans per ton applied. Overall, the results show that soil texture, organic matrix, and fertilizer physical form control nutrient persistence, redox adjustment, and early crop performance.

Terapia fotodinâmica, nanopartículas, lignina e quitosana no tratamento de sementes de trigo para controle de Alternaria spp.

2026-07-22T06:28:04Z

Title: Terapia fotodinâmica, nanopartículas, lignina e quitosana no tratamento de sementes de trigo para controle de Alternaria spp. Abstract: The expansion of wheat cultivation (Triticum aestivum L.) into the Brazilian Cerrado has intensified phytosanitary challenges associated with seed-borne pathogens, particularly Alternaria alternata, which is responsible for yield losses and reductions in the physiological and sanitary quality of seeds. At the same time, conventional chemical control has shown limitations related to the selection of resistant populations, environmental impacts, and adverse effects on seed vigor, reinforcing the need for alternative, sustainable, and effective seed treatment strategies. In this context, this thesis evalu-ated the potential of emerging technologies for the control of A. alternata, including metallic and semiconductor nanoparticles (NPs) (ZnO, ZnOCl, TiO₂, and TiO₂–Fe), silver-doped (ZnO:Ag, ZnOCl:Ag) and copper-doped nanoparticles (ZnO:Cu, ZnOCl:Cu), hybrid lignate–nanoparticle for-mulations (lignate:NP), chitosan, and the combination of NPs with photodynamic therapy (PDT) us-ing methylene blue (MB) and toluidine blue. The evaluations comprised in vitro assays, treatment of naturally contaminated seeds, and analysis of seed physiological quality, considering germination, vigor, emergence, and accelerated aging. The nanoparticles ZnO, ZnOCl:10%Cu, ZnO:10%Ag, and TiO₂:5%Fe exhibited in vitro antifungal activity by inhibiting A. alternata mycelial growth, with con-trol levels ranging from 49% to 88%. In the treatment of naturally contaminated seeds, the combina-tion of ZnOCl:11%Ag associated with PDT mediated by MB achieved 93% control of Alternaria alternata, which was statistically similar to conventional chemical treatment. The lignate:ZnOCl (75:25) formulation provided 69% control, while chitosan at 4% achieved 89% control, highlighting these approaches as effective and sustainable alternatives for pathogen management in wheat seeds. None of the treatments compromised seed germination, vigor, emergence, or performance after ac-celerated aging. Overall, the results demonstrate that NPs, lignate–nanoparticle systems, chitosan, and PDT, applied individually or in combination, exhibit antifungal potential against Alternaria al-ternata and represent effective alternatives for wheat seed treatment without impairing seed physio-logical quality, contributing to the sustainability of wheat production in the Brazilian Cerrado and to the consolidation of agricultural systems aligned with food security and environmental conservation goals.

Silício na incidência de pragas e doenças, na qualidade fisiológica de sementes e composição bromatológica do sorgo forrageiro

2026-07-09T06:21:33Z

Title: Silício na incidência de pragas e doenças, na qualidade fisiológica de sementes e composição bromatológica do sorgo forrageiro Abstract: The use of silicon (Si) to increase resistance against different pest species, diseases, and abiotic conditions such as water stress has been widely studied. However, most studies do not address the subsequent stages of crop production, such as the evaluation of seed quality or the nutritional quality of the produced plant material. Bromatological composition and seed quality are influenced by several factors, and different fertilization protocols may alter the characteristics of the seed and the plant as a whole. Given the above, this study aimed to investigate the effect of Si throughout the entire forage sorghum cycle, from increasing resistance to different insect pests and diseases to the physiological quality of the produced seeds and the bromatological composition of the plant material. To evaluate the increase in resistance and the physiological quality of the seeds, two experiments were conducted. One experiment evaluated different doses of Si (0, 300, 600, 900, and 1200 kg ha⁻¹ of Si, plus an additional treatment consisting only of soil correction), while the other experiment evaluated the absence and presence of Si (800 kg ha⁻¹ of Si) in relation to the absence and presence of chemical control, in a two-factor factorial design. The bromatological composition of sorghum was evaluated in the experiment with different Si doses. The experiments were carried out in an experimental field located at Glória Farm, where Si was applied to the soil in the form of calcium and magnesium silicate 30 days before planting. Si content was evaluated in the soil, leaf tissue, and seeds. Assessments of the percentage of plants showing symptoms of insect pest attack (aphids, caterpillars, and stink bugs) were performed at 23, 42, 49, and 56 days after crop emergence (DAE). Parameters related to production, such as yield and thousand-seed weight, were evaluated, in addition to the physical and physiological quality of the seeds through water content, germination, electrical conductivity, emergence, emergence speed index, mean emergence time, seedling dry mass, and accelerated aging. Bromatological analyses included the determination of ash, ether extract (lipids), crude protein, and neutral detergent fiber (NDF) and acid detergent fiber (ADF). There was an increase in Si content in the soil and leaf tissue with increasing silicate doses applied to the soil in both experiments; however, no difference was observed in the Si content of sorghum seeds. Si increased sorghum resistance to attacks by stink bugs of the genus Diceraeus Spinola in the first experiment and by Diceraeus spp. and caterpillars of Spodoptera frugiperda (Smith) in the second experiment, reducing the percentage of plants showing symptoms. The different silicate doses applied did not influence the production or physiological quality of sorghum seeds. The use of chemical control resulted in a slight increase in root dry mass regardless of Si use; however, chemical control had no effect on insect populations, seed production, or seed quality. Regarding bromatological composition, no effect of Si was observed on the percentages of ash, ether extract, crude protein, or NDF. When compared to the additional treatment, in which Si was not applied and lower amounts of Ca and Mg were supplied, an increase in ash content was observed at the dose of 900 kg ha⁻¹ and an increase in ADF at the dose of 1200 kg ha⁻¹. The reduction in insect attack, whether through the use of Si or chemical control, did not interfere with seed quality, and high doses of Si, Ca, and Mg in the soil may reduce the digestibility of forage sorghum. The benefits of Si in pest control outweigh the possible disadvantages related to forage sorghum digestibility, without affecting crop yield or seed quality.