http://repositorio.ufgd.edu.br/jspui/handle/prefix/198 Sun, 18 Jan 2026 02:57:56 GMT 2026-01-18T02:57:56Z http://repositorio.ufgd.edu.br/jspui/handle/prefix/6778 Título: Efeito de resíduos culturais no residual e eficácia de herbicidas pré-emergentes a base de s-metolacloro no controle de plantas daninhas na cultura da soja Autor(es): Ribeiro, Robson Alves Primeiro Orientador: Silva , Paulo Vinicius da Abstract: Pre-emergent herbicides are fundamental tools in integrated weed management. However, straw from the previous crop can act as a physical barrier, hindering the transport of these herbicides to the soil, reducing their availability in the solution and, consequently, their effectiveness in control. Thus, the objective of this study was to evaluate the influence of Zea mays L. (corn) straw intercropped with Urochloa ruziziensis cv. ruziziensis (R. Br. ex A. Rich.) R.D. Webster and Sorghum bicolor (L.) Moench (sorghum) straw on the availability of s-metolachlor in the soil, as well as the efficiency of preemergent herbicides in controlling Amaranthus hybridus L., Eleusine indica (L.) Gaertn., Digitaria horizontalis Willd., and Cenchrus echinatus L., on the establishment and productivity of soybeans. The experiment was conducted in randomized blocks, with four replicates, in a 5 × 3 + 2 and 5 × 3 factorial design. Factor A consisted of five preemergent herbicides (s-metolachlor, s-metolachlor + fomesafen, s-metolachlor + metribuzin, s-metolachlor + flumioxazine, and s-metolachlor + sulfentrazone) and two herbicide-free controls, while factor B consisted of three straw conditions (no straw, corn straw intercropped with Urochloa ruziziensis cv. ruziziensis, and sorghum straw). All herbicides showed high efficiency (>90%) in controlling A. hybridus, D. horizontalis, and C. echinatus. The presence of straw increased control by an average of 14% for D. horizontalis, C. echinatus, and E. indica, and 9% for A. hybridus, compared to the absence of cover. The concentration of s-metolachlor in the soil showed similar behavior between straw conditions, which may be associated with precipitation of 28 mm at 2 DAA, sufficient to promote the transport of the herbicide to the soil. Up to 10 DAA, there was an 87.6% reduction in the total applied, coinciding with the period of highest rainfall. The differences between the s-metolachlor formulations were attributed only to the doses applied, and the higher doses did not prolong the residual period in the soil. The types of straw did not interfere with the concentration of s-metolachlor or the efficiency of the herbicides, due to favorable weather conditions for transport. No visual symptoms of phytotoxicity were observed, although there was a reduction in plant stand. The straws provided better conditions for the initial establishment of soybeans, especially corn straw intercropped with Urochloa ruziziensis cv. Ruziziensis. It is concluded that corn straw intercropped with Urochloa ruziziensis cv. ruziziensis and sorghum straw are effective tools in integrated weed management when associated with preemergent herbicides, without interfering with the concentration of s-metolachlor in the soil under adequate precipitation conditions. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação Tue, 02 Sep 2025 00:00:00 GMT http://repositorio.ufgd.edu.br/jspui/handle/prefix/6778 2025-09-02T00:00:00Z http://repositorio.ufgd.edu.br/jspui/handle/prefix/6708 Título: Magnésio via foliar para atenuação de estresse fisiológico de herbicidas na soja Enlist Autor(es): Caneppele, Giuzeppe Augusto Maram Primeiro Orientador: Santos, Elcio Ferreira dos Abstract: Soybean (Glycine max (L.) Merrill) is one of Brazil's main crops, and the use of herbicide-tolerant cultivars, such as Enlist™ E3 soybean, facilitates weed management but can cause physiological stress that compromises productivity. Given this, the present study aimed to evaluate the effects of foliar application of magnesium (Mg) in mitigating the physiological stress caused by these herbicides in Enlist™ E3 soybeans. The study was conducted through three field experiments in Mato Grosso do Sul (Caarapó, Dourados, and Juti) during the 2024/2025 harvest in an area planted with Enlist™ E3 soybeans. It was conducted in a completely randomized design, in a 5 x 5 factorial scheme, with five doses of Mg (0, 50, 100, 150, and 200 g ha⁻¹), using magnesium sulfate as the source, and five herbicides, without weeding: glyphosate (1500 g a.e. ha⁻¹), 2,4-D choline salt (1000 g a.e. ha⁻¹), glufosinate (500 g a.e. ha⁻¹), and weeding. The experimental plots measured 3 × 5 meters. This allowed for an integrated assessment of the effects of herbicides and foliar fertilization on the Enlist™ E3 soybean crop. Physiological parameters, nutritional analysis of plant tissue, photosynthetic rate, stomatal conductance and transpiration, photosynthetic pigment content, nitrogen compounds, total sugars, and sucrose in the leaves were measured. Visual symptoms of phytotoxicity and final grain yield were also evaluated. The data were analyzed using variance and regression. For qualitative factors, the means were compared using Tukey's test at 5%. For quantitative factors, regression models were selected based on the significance of the coefficients (t-test), the coefficient of determination (r²), and the biological consistency of the fit. The results showed that herbicides negatively affected the physiology of Enlist™ E3 soybeans. Significant reductions were observed in the photosynthetic rate, accumulation of soluble sugars, and concentration of photosynthetic pigments, in addition to an increase in phytotoxicity symptoms. However, foliar magnesium supplementation proved to be highly effective in mitigating these adverse effects. Foliar fertilization increased magnesium levels in leaf tissues, promoting greater integrity of photosynthetic pigments and favoring the maintenance of photosynthetic activity. An increase in stomatal conductance and sugar concentration was also observed. These benefits were directly reflected in productivity. Foliar application of magnesium reduced physiological stress symptoms, increased foliar nutrient levels, increased photosynthetic efficiency, sugar accumulation, and soybean productivity, especially in areas without weed competition. It was concluded that foliar supplementation with Mg is a viable and effective practice to mitigate the effects of herbicides and promote crop productivity. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação Fri, 29 Aug 2025 00:00:00 GMT http://repositorio.ufgd.edu.br/jspui/handle/prefix/6708 2025-08-29T00:00:00Z http://repositorio.ufgd.edu.br/jspui/handle/prefix/6645 Título: Performance comparativa de cultivares de soja transgênica Bt e não-Bt sobre a população de Spodoptera frugiperda (J. E. SMITH, 1797) (Lepidoptera: Noctuidae) e suas implicações agronômicas Autor(es): Souza, Victor Luiz Peres de Primeiro Orientador: Fernandes, Marcos Gino Abstract: Soybean (Glycine max (L.) Merrill) is one of the most important agricultural crops globally, with Brazil leading world production. However, pests constantly threaten soybean productivity, notably S. frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae), a polyphagous caterpillar that causes significant damage. Bt technology, which consists of inserting genes from the bacterium Bacillus thuringiensis Berliner (Bt) into plants to express insecticidal proteins (Cry), has been a crucial tool in integrated pest management. However, the effectiveness of this technology can be challenged by the evolution of insect resistance and vary according to edaphoclimatic conditions. This study aimed to evaluate the impact of different transgenic soybean (Bt) cultivars on the S. frugiperda population and its agronomic implications in three municipalities of Mato Grosso do Sul (Ponta Porã, Dourados, and Rio Brilhante). Cultivars with and without Bt technology were compared in terms of productivity, thousand-seed weight, plant height, and caterpillar infestation. The field study results indicated that the Bt cultivar BMX65k67, with Cry1Ac and Cry1F proteins, showed the best overall performance, with an average productivity of 3,273.3 kg/ha and the lowest infestation of large caterpillars (8.8 units), demonstrating the effectiveness of gene pyramiding. Non-Bt cultivars, such as M6101 and BRS 243, showed high susceptibility, resulting in lower productivity and higher pest infestation. The performance of the cultivars was also influenced by edaphoclimatic conditions, with Rio Brilhante presenting higher productivities. These results reinforce the strategic role of pyramided Bt cultivars in the management of S. frugiperda, especially in environments with high pest pressure, for soybean production stability, but it must be integrated with resistance management practices and adapted to local conditions. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação Thu, 28 Aug 2025 00:00:00 GMT http://repositorio.ufgd.edu.br/jspui/handle/prefix/6645 2025-08-28T00:00:00Z http://repositorio.ufgd.edu.br/jspui/handle/prefix/6639 Título: Plantas de cobertura melhoram a disponibilização do fósforo e micorrização da soja? Autor(es): Chaves, Mayara Regina Primeiro Orientador: Alovisi, Alessandra Mayumi Tokura Abstract: Cover crop cultivation improves soil fertility and benefits subsequent crops, in addition to promoting nutrient cycling, especially phosphorus. In this sense, the objective of this study was to evaluate the changes promoted by cover crops in soil chemical attributes, glomalin production, mycorrhization rate, soil phosphorus sorption, and nutritional attributes and agronomic characteristics of soybean. For this purpose, the study was developed in the experimental area of the School Farm of the Federal Institute of Mato Grosso do Sul, Naviraí Campus. The experimental design was randomized blocks, with six treatments and four replicates, totaling 24 experimental units. The treatments consisted of: Treatment 1- Soybean/Fallow; Treatment 2-Soybean/Millet; Treatment 3- Soybean/Crotalaria (Crotalaria ochroleuca); Treatment 4-Soybean/Forage radish; Treatment 5- Soybean/Second-crop Corn and Treatment 6- Soybean/Second-crop Corn + Brachiaria (Urochloa ruziziensis). Soil samples were collected before soybean cultivation, at flowering and after crop harvest. The soil chemical attributes (pH, OM, P, K, Ca, Mg, H+Al, SB, CTC, V% and P sorption), glomalin content, soybean root mycorrhization rate, nutritional attributes and agronomic characteristics of soybean (plant height, population, number of pods, number of grains, weight of 1000 grains and productivity) were evaluated. The data were submitted to analysis of variance (ANOVA) and when significant to the F test and the comparison of means was performed by the Scott-Knott test at 5% probability. In the chemical attributes, crotalaria presented the best results for most of the variables analyzed. Glomalin production was not affected by the treatments, but was influenced by the collection times, with the highest concentrations occurring during flowering and after soybean cultivation. Regarding the mycorrhization rate, crotalaria and fallow presented the highest percentages of mycorrhizal colonization. Cover crops were efficient in reducing phosphorus fixation in the soil (P sorption). Agronomic characteristics were positively affected by cover crops. Therefore, productivity was enhanced by the presence of cover crops, together with the chemical attributes and other parameters evaluated. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação Mon, 03 Mar 2025 00:00:00 GMT http://repositorio.ufgd.edu.br/jspui/handle/prefix/6639 2025-03-03T00:00:00Z