Revista Ceres

Modulation of the droplet spectrum by working pressure, adjuvants, and herbicides

2026-05-21T16:13:50-03:00

The droplet spectrum is a crucial factor in optimizing herbicide efficacy and minimizing spray drift. This study evaluated the effects of working pressure (100 to 600 kPa) and six adjuvants on droplet size, both in the absence and presence of herbicides, using an air-induction nozzle (TTI 110015VP) and a particle analyzer. Higher working pressures reduced droplet size – measured as Dv0.1, Dv0.5 (volume median diameter), and Dv0.9, representing the diameters at which 10%, 50%, and 90% of the total spray volume consists of droplets of that size or smaller – and increased the volume percentage of fine droplets (V100), regardless of the adjuvant or herbicide. Adjuvants influenced the droplet spectrum, with Xtend Protect1 significantly reducing Dv0.9. However, the lowest relative span, indicating greater droplet size uniformity, was achieved by different adjuvants depending on the working pressure. A significant interaction between herbicides and adjuvants was observed, underscoring the need for a comprehensive analysis of these variables to optimize application quality. The addition of adjuvants and herbicides to the spray solution altered the correlations between droplet spectrum variables, emphasizing the importance of considering multiple factors in application decisions. Selecting the appropriate working pressure and adjuvant, along with a thorough analysis of the droplet spectrum, is essential for effective weed control, reducing spray drift, and ensuring environmental, applicator, and consumer safety.

Gaussian process regression as an alternative to kriging and SVM for spatial yield prediction

2026-05-21T16:57:09-03:00

Detecting spatial yield variability is essential for precision agriculture because it minimizes environmental impact and enhances economic returns. This study proposes Gaussian Process Regression (GPR) as a predictive model for yield estimation, particularly in cultivated areas where the highest yields appear in the central region of the field, while the edges exhibit lower productivity. The study was conducted in Patos de Minas, Brazil, using 795 georeferenced soybean yield samples over 3.7 hectares. The analysis evaluates GPR across different sample sizes and compares it with Ordinary Kriging (OK) and Support Vector Machine (SVM). The results indicate that GPR and OK perform similarly under high sampling densities, but GPR achieves higher predictive accuracy under low-sampling conditions. A sample size of at least 60% of the full dataset is necessary to maintain reliable spatial prediction, as
smaller sample sizes lead to greater prediction errors and less defined spatial patterns. SVM, in contrast, produces a smoothing effect across all sampling densities, which reduces its ability to capture local variations. These findings highlight GPR as a robust alternative for yield mapping, particularly in scenarios with limited data availability. From a practical perspective, GPR and OK remain strong candidates for yield prediction, reinforcing the importance of model selection based on data availability and spatial variability.

Agronomic performance of wheat cultivars under different plant density and planting times

2026-05-21T17:12:06-03:00

Wheat plays a critical role in global food security and the agricultural economy. In Minas Gerais, Brazil, one of the major challenges for wheat production is the high variability of meteorological conditions. Therefore, studies that support wheat producers in defining more accurate sowing dates and plant densities according to cultivar requirements are essential, as they can contribute to increasing yield and enhancing agricultural resilience. The aim of this study was to evaluate the response of wheat cultivars, based on growth, micrometeorological, and yield-related traits, under different sowing times and plant densities. The experiment was conducted during the autumn–winter growing season of 2022 in an experimental area located in Ijaci, Minas Gerais, Brazil. Four wheat cultivars were evaluated under different sowing times and plant densities. Agronomic and agrometeorological variables were monitored throughout the field experiment. The results showed that wheat sown within the recommended sowing window exhibited superior performance, benefiting from greater soil water availability, higher growth rates, and increased radiation interception. Grain yield was, on average, 37.9% higher under normal sowing conditions compared with late sowing, confirming the strong influence of sowing time on crop performance. No significant differences were observed among cultivars or plant densities. These findings provide relevant guidance for producers and reinforce sowing time as a key factor for efficient wheat management

Ethylene inhibitor, 1-methylcyclopropene, delays macauba fruit ripening and preserves oil quality

2026-05-21T16:40:22-03:00

The macauba palm produces high-quality oil, with oil content in the fruit potentially increasing after harvest. However, storage limitations due to microorganism and metabolism deterioration restrict the fruit's shelf life. This study evaluated the effects of the ethylene inhibitor 1-MCP on the physiological, physical, and chemical characteristics of macauba palm fruits, focusing on oil quality preservation during storage. Various concentrations of 1-MCP (0, 1000,2000, and 3000 nL L-1) were applied over two exposures (12 and 24 hours) times during fruit storage, assessed at six intervals. Untreated fruits exhibited damaged mesocarpand spoilage by the end of storage, while 1-MCP treatment notably suppressed spoilage. The inhibitor reduced respiration and ethylene production throughout storage, although it did not completely prevent climacteric peaks of CO2 and ethylene, which lessened with higher 1-MCP concentrations. Additionally, 1-MCP delayed ripening, reflected in slower accumulation of total soluble solids and reduced mesocarp firmness loss. Treated fruits showed smaller increases in mesocarp oil content during storage, and the inhibitor also slowed oil acidification. Overall, the responses in all parameters improved with higher 1-MCP concentrations, indicating that 1-MCP could be an effective post-harvest strategy for maintaining the quality of macauba palm fruits and their oil.

Physicochemical Properties of Monguba Seeds (Malvaceae fruit) at Different Ripening Stages

2026-05-21T17:24:16-03:00

Pachira aquatica Aubl., popularly known in Brazil as Monguba, is an unconventional food plant (UFP) found in tropical regions of Central and South America. In the Amazon region, its seeds are traditionally consumed boiled, roasted, or fried and may also be incorporated into cakes and sweets. Despite this cultural use and the nutritional potential of its seeds, commercial exploitation remains limited. This study aims to assess physicochemical disparities between ripe and unripe Monguba seeds. In the physical characterization, the main differences were in the seeds: unripe seeds exhibited a higher mucilage content (1.3 g) and denser pericarp (4.5 g), while ripe seeds presented more pulp (12.9 g) and darker coloration. Chemically, ripe and unripe seeds contained high lipid and protein levels (35.6–32.5% and 13.0–12.7%, respectively). Ripe seeds showed an increase in carbohydrates (45.8%)
and minerals, like calcium (82.3 mg.100 g-1), magnesium (65.2 mg.100 g-1), manganese (1.4 mg.100 g-1), and zinc (2.1 mg.100 g-1), while unripe seeds showed higher acidity (23.9%) and lower °Brix (12.8). FTIR spectra revealed differences in polysaccharide hydrolysis and cell wall lignification during ripening. These findings emphasize the importance of exploring the various stages of plant development.

Moderate doses of selenium alleviate the effects of salt stress on the growth of eucalyptus seedlings

2026-05-27T08:45:33-03:00

Although selenium (Se) is not essential for plant metabolism, low Se concentrations can enhance tolerance to abiotic stress. This study evaluated the effects of exogenous Se (1, 5, and 25 μM) on two eucalyptus genotypes (VCC 865 and AEC 0144) under saline stress (100 mM NaCl). Growth, biomass, gas exchange, ion accumulation (K+, Na+, Ca2+), and pigment content were analyzed. Salinity significantly impaired physiological performance, reducing height, stem diameter, net photosynthesis (PN), transpiration (Tr), and stomatal conductance (gs), while increasing Na+ in roots and leaves. Se at 1 and 5 μM mitigated these effects, particularly by reducing Na+ accumulation. VCC 865 showed increased K+ in roots and decreased Na+ in shoots with 1 μM Se, while AEC 0144 displayed improved ionic balance in roots and leaves. The chlorophyll pigment content remained unchanged between the treatments. However, 25 μM Se intensified salinity damage, indicating the importance of dose optimization. Photosynthetic parameters were sensitive indicators of Se-mediated responses. Therefore, the targeted use of selenium represents a promising strategy to improve seedling establishment in environments affected by salinity, contributing to the development of more resilient forest systems and the expansion of areas suitable for production.

Emergence and initial growth of sesame under variations in irrigation water quality and proportion of plant ash

2026-05-21T15:45:45-03:00

Under saline conditions, the seed germination process is often impaired. Thus, the use of organic residues may represent an alternative to mitigate salt stress in plants. This study aimed to investigate sesame seed germination and early growth, considering the influence of irrigation water quality and the proportion of plant ash in the substrate. Conducted at the Federal Rural University of Pernambuco, the experiment tested different proportions of sugarcane bagasse ash [0%, 13%, 26%, 40%, 54%] and irrigation water qualities (0.3, 1.8, and 4.1 dS m-1). The ashes did not mitigate the effects of irrigation water salinity, and their increase had negative effects on emergence percentage. However, an ash proportion of up to 13.7% increased the emergence speed index when non-saline water (0.3 dS m-1, control) was used, but under saline water conditions, it caused detrimental effects. Average emergence time and average emergence speed showed positive results with ash proportions up to 21% when non-saline water was used. Plant height, stem diameter, and root length were negatively affected by higher ash proportions in the substrate, especially under irrigation with saline water.