http://repositorio.ufgd.edu.br/jspui/handle/prefix/199 Sun, 25 Oct 2026 02:09:58 GMT 2026-10-25T02:09:58Z http://repositorio.ufgd.edu.br/jspui/handle/prefix/7150 Título: Remineralizadores e KCL como fonte de potássio para a sucessão soja-milho Autor(es): Rosa, Jaqueline Maronez Primeiro Orientador: Alovisi, Alessandra Mayumi Tokura Abstract: Potassium is the second most absorbed mineral nutrient by plants and presents low residual effect in the soil due to the high solubility of potassium chloride, the most used source in agriculture. In this context, the objective of this study was to evaluate the effect of five doses and three sources of potassium on the chemical attributes of the soil, as well as on the productive and nutritional characteristics of soybean and maize, including the residual effect on second crop maize, in a dystrophic Red Latosol. The experiment was conducted at the Experimental Farm of Agricultural Sciences (FAECA) of the Federal University of Grande Dourados (UFGD) during the 2021/2022 and 2022/2023 seasons for soybean, and the 2022 and 2023 seasons for maize. A randomized block design was used, arranged in a 5 × 3 factorial scheme with four replications, totaling 60 experimental units. The treatments consisted of five K₂O doses (0, 25, 50, 75, and 100% of the recommended K₂O dose, corresponding to 0, 25, 50, 75, and 100 kg ha⁻¹ of K₂O) and three K sources [potassium chloride (60% K₂O), phonolite (8% K₂O; 25% Si), and hydrothermally treated phonolite (12% K₂O; 25% Si)]. Soil chemical attributes and potassium desorption were evaluated, as well as macro- and micronutrient concentrations in diagnostic leaves, yield components, and grain productivity. Data were subjected to analysis of variance; polynomial regression was applied for K doses, and Tukey’s test for K sources, using the SISVAR statistical software. For Ca, the highest levels were obtained with phonolite and hydrothermally treated phonolite, which promoted gradual nutrient release and improved cation exchange capacity. Phosphorus content was not affected by sources or doses, remaining within adequate levels. KCl increased Cu and Zn levels, whereas hydrothermally treated phonolite showed a more balanced effect on micronutrients and greater stability in Fe release. Application of K₂O sources and doses influenced nutrient availability and crop productivity. In soybean, hydrothermally treated phonolite stood out by maintaining higher yields under water deficit conditions (2021/22 season) and performance equivalent to KCl under favorable conditions (2022/23). Antagonism among K, Ca, and Mg was observed, especially with KCl, while hydrothermally treated phonolite reduced this effect, ensuring better nutritional balance. In maize, K₂O sources did not differ significantly, although phonolite showed a slight advantage at intermediate doses. Overall, hydrothermally treated phonolite proved to be the most efficient K₂O source, providing chemical stability, nutritional balance, and productivity comparable to or greater than KCl, establishing itself as a sustainable alternative for potassium fertilization. Editor: Universidade Federal da Grande Dourados Tipo: Tese Fri, 07 Nov 2025 00:00:00 GMT http://repositorio.ufgd.edu.br/jspui/handle/prefix/7150 2025-11-07T00:00:00Z http://repositorio.ufgd.edu.br/jspui/handle/prefix/7145 Título: Efeito mitigador do silicato de potássio, extrato de algas e Bacillus subtilis no potencial de recuperação de mudas de Cedrela fissilis Vell., sob estresse hídrico Autor(es): Bernardes , Rodrigo da Silva Primeiro Orientador: Scalon , Silvana de Paula Quintão Abstract: Global climate change has made morphophysiological and biochemical alterations in plants more frequent in response to abiotic stresses. In this context, water limits plant development due to increased water deficits and extreme flooding. This scenario reinforces the need to deepen ecophysiological knowledge for the production of high-quality forest seedlings. Thus, strategies are sought to mitigate metabolic damage and increase tolerance to water fluctuations. The use of biostimulants emerges as an alternative to increase plant resilience, with potassium silicate acting in structural and water support, algae extract in metabolic-hormonal balance, and B. subtilis in root promotion and resistance induction. Therefore, the present study aimed to evaluate the morphophysiological, biochemical, and antioxidant metabolisms of Cedrela fissilis Vell. seedlings. This study aimed to evaluate the effects of water stress on seedlings subjected to different water conditions, as well as their recovery potential, and to determine if the application of potassium silicate, seaweed extract (Ascophyllum nodosum), and B. subtilis, alone or in combination, can mitigate the effects of water stress. In the first experiment, seedlings were subjected to flooding, with or without the application of mitigators, and growth, gas exchange, photochemical efficiency, and antioxidant activity were evaluated during stress and after the recovery phase. It was found that flooding significantly compromised the photosynthetic metabolism and growth of untreated seedlings, while the application of mitigators promoted greater maintenance of the photosynthetic rate, recovery of stomatal conductance, and stability of the photosynthetic apparatus. Potassium silicate stood out for promoting structural integrity and photochemical efficiency, while inoculation with B. subtilis contributed to morphological and osmotic adjustments, resulting in greater preservation of leaf architecture. In the second experiment, seedlings were subjected to water fluctuation, characterized by alternating water deficit, rehydration, and subsequent flooding, associated or not with the application of potassium silicate and B. subtilis. It was observed that the initial water deficit promoted a significant reduction in photosynthetic activity, stomatal closure, and limitation of gas exchange, regardless of the application of mitigators at that time. However, during recovery and subsequent flooding stress, it became evident that the treatments with potassium silicate and bacteria reconfigured the physiological response of the seedlings, conferring greater tolerance to sequential stress. Potassium silicate contributed to membrane stability and reduced dependence on intense enzymatic antioxidant responses, while B. subtilis favored osmotic adjustment and biomass maintenance. The activity of antioxidant enzymes revealed a high metabolic cost associated with the history of stress in untreated seedlings, while the mitigators allowed for more balanced and efficient responses. Overall, the results demonstrate that C. fissilis is sensitive to variations in water availability, but exhibits high physiological plasticity when subjected to appropriate management strategies. The application of potassium silicate and B. subtilis proved efficient in mitigating damage caused by isolated or sequential water stresses, promoting complementary mechanisms of tolerance and recovery. These results reinforce the importance of adopting mitigating practices even in the nursery phase, aiming at the production of more resilient seedlings with greater survival potential in environments subject to water instability. Editor: Universidade Federal da Grande Dourados Tipo: Tese Tue, 03 Mar 2026 00:00:00 GMT http://repositorio.ufgd.edu.br/jspui/handle/prefix/7145 2026-03-03T00:00:00Z http://repositorio.ufgd.edu.br/jspui/handle/prefix/7096 Título: Densidade, adubação nitrogenada e marcha nutricional em girassol de corte Autor(es): Taira, Tiago Ledesma Primeiro Orientador: Sorgato, José Carlos Abstract: This thesis investigated the optimization of production and post-harvest quality of cut sunflower (Helianthus annuus L.), cultivar 'Vincent’s Choice', within the context of floriculture market demands. The research sought to provide information on the agronomic management and specific nutritional dynamics of this cultivar, which is distinct from those intended for grain production. The study was structured into two complementary chapters that addressed the effects of management factors and the characterization of the nutrient uptake rate. In the first chapter, the impacts of two planting densities (20 and 32 plants m⁻²) and six topdressing nitrogen fertilization doses (0, 10, 20, 30, 40, and 50 g N m⁻²) on production and post-harvest longevity were evaluated. The results evidenced a significant interaction between density and N doses on the capitulum diameter. Only the combination of low planting density (20 plants m⁻²) with the maximum nitrogen dose (50 g N m⁻²) enabled obtaining flower heads with an average diameter exceeding 60 mm, qualifying the floral stems for the commercialization standard (Veiling Holambra Standard). In contrast, stem longevity, the onset of yellowing, and the dropping of ray florets—post-harvest characteristics—were not significantly altered by the treatments, suggesting that such attributes are predominantly determined by the cultivar's genotype. The second chapter determined the dry matter accumulation and the uptake rate of macro and micronutrients in the shoot of the 'Vincent’s Choice' cultivar. Dry matter accumulation followed a sigmoid pattern, with the stem becoming the main biomass storage organ at 36 days after emergence (DAE), surpassing the leaves. Potassium (K) was the most accumulated macronutrient (2,316 g plant⁻¹), followed by nitrogen (N) (1,058 g plant⁻¹). Among the micronutrients, manganese (Mn) and zinc (Zn) showed the highest accumulations. The analysis of the Inflection Points (IP) revealed that the maximum daily absorption rate of N and K occurred, respectively, between 32.85 and 33.95 DAE, a critical period of high nutritional demand spanning the vegetative and the beginning of the reproductive stages. Additionally, the remobilization of Phosphorus (P), Magnesium (Mg), and Copper (Cu) from the leaves and stem to the capitulum was observed in the final stages of the cycle, as well as a preferential allocation of K in the stem, a fundamental factor for the rigidity and structural quality of the floral stem. The results of this thesis provide unprecedented scientific evidence for the formulation of precision fertilization programs and for the inclusion of the crop within the parameters of Floriculture 5.0. The research emphasizes the importance of adjusting planting density and synchronizing the supply of inputs with the periods of maximum physiological demand, aiming to optimize management, ensure the commercial quality of 'Vincent’s Choice' stems, and align high-performance productivity with sustainability in national floriculture. Editor: Universidade Federal da Grande Dourados Tipo: Tese Fri, 12 Dec 2025 00:00:00 GMT http://repositorio.ufgd.edu.br/jspui/handle/prefix/7096 2025-12-12T00:00:00Z http://repositorio.ufgd.edu.br/jspui/handle/prefix/7095 Título: Aspectos produtivos da sucessão soja milho, resistência à penetração do solo e atividade enzimática sob diferentes estratégias de formação de palhada Autor(es): Oliveira, Bruno Levino de Primeiro Orientador: Mauad, Munir Abstract: The objective of this study was to evaluate the agronomic performance of corn and soybean in different crop rotation systems. The research was conducted at the Experimental Farm of the Faculty of Agricultural Sciences of UFGD, in Dourados, MS, during the 2021/2022 and 2022/2023 growing seasons. The experiment was arranged in a randomized block design with 16 treatments and four replications. The treatments consisted of monocropping of corn, Urochloa brizantha cvs. BRS Marandú, BRS Paiaguás, BRS Piatã, BRS Xaraés, and Urochloa ruziziensis cv. Kenedy, as well as corn intercropped with each forage species, with or without suppression using nicosulfuron associated with atrazine. In both soybean seasons, plant height, first pod insertion height, number of branches per plant, number of pods per plant, thousand-grain weight, and yield were evaluated. For the corn crop, plant height, stem diameter, ear length, number of grains per ear, thousand-grain weight, and yield were analyzed. The amount of straw after forage management was also assessed, and in 2023, soil penetration resistance and the activity of the enzymes arylsulfatase and β-glucosidase were measured. The treatments did not influence soil penetration resistance or the activity of arylsulfatase and β glucosidase, whose values were considered high across all treatments. Additionally, no statistical differences were observed in soybean yield components or productivity in either production year. For corn, only yield in the second 2022 season was affected by the treatments, with the lowest yields observed in the unsuppressed intercropping treatments of corn with U. ruziziensis and corn with U. brizantha cv. Paiaguás, which negatively impacted corn production. Regarding straw production for no-tillage, no statistical differences were detected among treatments in either growing season. However, in the second 2021 season, low rainfall resulted in straw production below 6 Mg ha⁻¹ year⁻¹ in the monocropping treatments of corn, BRS Marandú, BRS Paiaguás, and BRS Xaraés, as well as in the intercropping treatments corn+Paiaguás with suppression, corn+Ruziziensis with and without suppression, and corn+Xaraés with suppression. The inclusion of tropical forages, either in sole cropping or intercropped with corn in the second season, is a viable strategy, as it does not compromise the productivity of the main crops. Editor: Universidade Federal da Grande Dourados Tipo: Tese Fri, 04 Jul 2025 00:00:00 GMT http://repositorio.ufgd.edu.br/jspui/handle/prefix/7095 2025-07-04T00:00:00Z