https://repositorio.ufra.edu.br/jspui/handle/123456789/18 Programa de Pós-Graduação em Agronomia Thu, 09 Apr 2026 10:21:25 GMT 2026-04-09T10:21:25Z https://repositorio.ufra.edu.br/jspui/handle/riufra/2861 Título: Distribuição espacial e amostragem sequencial de Spodoptera frugiperda (J.E. Smith, 1797) na cultura do milho. Autor(es): FARIAS, Paulo Roberto Silva Abstract: With the aim of studying the distribution of Spodoptera frugiperda (J.E. Smith, 1797) in corn crops, a stratified sampling system was implemented, consisting of three fields, each comprising 100 plots, conducted in a corn field at the Faculty of Agricultural and Veterinary Sciences in Jaboticabal during the 1994/1995 growing season. The number of caterpillars per plant was counted on 16 sampling dates. The data obtained were fitted to the negative binomial, Poisson, and positive binomial distributions. The following aggregation indices were also studied: dispersion index (s/m), Morisita index, |d statistic, K parameter of the negative binomial distribution, and the b coefficient of Taylor’s law. The number of caterpillars per plant was counted on 16 sampling dates. The data obtained were fitted to negative binomial, Poisson, and positive binomial distributions. The following aggregation indices were also studied: dispersion index (s/m), Morisita index, |d statistic, K parameter of the negative binomial distribution, and the b coefficient of Taylor’s law. The studies revealed that the numbers of small caterpillars per plant fit the negative binomial distribution, while the numbers of large caterpillars exhibited a distribution tending toward randomness. The aggregation indices showed a marked tendency toward aggregated spatial distribution for small, large, and total S. frugiperda. Sequential sampling plans were constructed based on the number of caterpillars per plant and on the percentage of infested plants. Tue, 31 Mar 2026 00:00:00 GMT https://repositorio.ufra.edu.br/jspui/handle/riufra/2861 2026-03-31T00:00:00Z https://repositorio.ufra.edu.br/jspui/handle/riufra/2859 Título: Eficiência da adubação fosfatada e potássica na cultura da soja. Autor(es): ASSIS, Tatiana Castro de Abstract: Soybean (Glycine max) crops had spread in 70's due to increasing international demands and credit availability by the Brazilian government. Major soybean crops had establisted in Southern and Southeastern Brazil which, besides of having appropriate soil and climate conditions for soybean cultivation were closer to export shipping ports. In the past ten years, soybean crops have been expanding to low latitude regions of Brazil, reaching Amazon region. Those new extent a neas have led to the need of generating appropriate technologies and management for soybean cultivation in that new agricultural frontier. Howover application of fertilizer should be made based on the response of soybean varieties to fertilizers, in local conditions in order to maximize economical return per area unit. In the state of Para soybean cropping area have been increasing, especially in the Southern and Weastern Para. Researches on fertilization and mineral nutrition are incipient that in by fertilizer application has been recommended based on the results obtrined in other cropping areas in Brazil. The present research was carried out in order to establish response curves of soybean to phosphorus and potassium. The experiment were conducted at Embrapa Amazônia Oriental experimental fields. in Paragominas and Belterra counties using soybean. Sambaiba cultivar growin in representative soil type, for each area. Soil analysis were performed prior to the experiment istallation, soppling layers from 0 to 20 cm depth, for physical and chemical characterization. The experimental design was a randomized blocks with four replications, with the treatments arranged in a 4 x 4 factorial design, corresponding to four phosphorus levels (0, 80, 160 and 240 kg ha¹ P205) using simple superphosphate as P source and four potassium levels (0. 60. 120 and 180 kg ha K20) as potassium chloride were tested. Phosphorus fertilizer was applied once in planting groove while potassium was split in two dosis, one third applied at time of planting and two third in coverage, 30 days after germination. The fertilizer effects were recordes as plant height first legume insert, bending, days to flower onset. 100 seed weight. seed moisture, at harvest, yield. pests. diseases and chemical analysis at soil and plants. Data obtained were analysis by ANOVA and regression analyses. The results obtained have shown that the annual application of 80 kg.ha P₂Os and 60 kg.ha K₂O was enough to keep a good grouth and yield at about 90% of maximum productivity and to maintain the critical level phosphorus and potassium in the soil. Increases in potassium content resulted in drops of calcium and magnesium in content dry matter. Phosphorus and potassium contents in leaves were larger in Belterra than Paragominas. Nitrogen and potassium were the nutrients taken up in higher proportion, being followed, in decreasing order, by Ca, Mg, P and S in soybean dry matter. In soil Oxisol with low content of P and K after applied of 80 kg ha of P₂Os and 60 kg ha¹ of K₂O soybean cv. Sambaiba 3.600 kg ha", a good performance wher compared with Brazilian average. Wed, 25 Mar 2026 00:00:00 GMT https://repositorio.ufra.edu.br/jspui/handle/riufra/2859 2026-03-25T00:00:00Z https://repositorio.ufra.edu.br/jspui/handle/riufra/2857 Título: Danos foto-oxidativos e sistema de defesa antioxidante em dois híbridos de palma de óleo (Elaeis Guineensis jacq.) submetidos ao estresse salino. Autor(es): TEIXEIRA, Keila Beatriz Silva Abstract: Considering that oil palm plantations are generally not irrigated and that there is intensive use of fertilizers, it is possible to assume that, during the dry season, reduced water availability combined with the accumulation of salts in the soil can lead to salinization. This condition can affect the physiology and growth of palm trees, as salt stress triggers metabolic changes, including the excessive production of reactive oxygen species. Therefore, the study aimed to evaluate a possible differential response to photooxidative damage to photosystem II and the ability of these plants to adjust antioxidant enzymes (superoxide dismutase, SOD; ascorbate peroxidase, APX; and catalase, CAT) as a primary cellular defense mechanism. To this end, two oil palm hybrids—Tenera and BRS Manicoré—were subjected to saline stress induced by daily irrigation with a NaCl solution, the concentration of which was gradually increased until reaching 400 mM. The experiment was conducted in a 2 × 2 factorial design with four replicates, involving a combination of the two hybrids and two salinity conditions (control, without NaCl addition; and saline stress, with NaCl addition). To evaluate stress tolerance, several parameters were analyzed, such as pre-morning water potential (Ψam), maximum photochemical efficiency of photosystem II (Fv/Fm), maximum photochemical efficiency of photosystem II in the presence of light (F’v/F’m), the ratio of initial fluorescence in the dark to variable fluorescence in the light (F0/F’v), and non-photochemical dissipation coefficient (NPQ), photochemical dissipation coefficient (qP), effective quantum efficiency (ΦPSII), quantification of pigments such as chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophylls (Chl a+b) and chlorophyll a to b ratio (Chl a/b), xanthophylls, carotenoids and anthocyanins were also evaluated. In addition, the levels of malonic aldehyde and hydrogen peroxide were evaluated, and to evaluate the antioxidant system, the activities of SOD, APX and CAT were estimated. Salt stress significantly reduced the water potential in both hybrids, to the same extent. A reduction in the values of Fv/Fm, F'v/F'm and FPSI were also observed, in addition to an increase in qP in both genotypes. The degradation of chloroplast pigments was significant only in the Tenera hybrid. In BRS Manicoré, the non-photochemical dissipation coefficient (NPQ) increased sixfold compared to the control. Regarding oxidative stress markers, malonic aldehyde levels increased in both hybrids. Hydrogen peroxide levels increased in BRS Manicoré but decreased in Tenera. SOD activity increased in both hybrids under stress, while APX and CAT activities were reduced, with this reduction being more significant in Tenera. It is concluded that BRS Manicoré demonstrated greater tolerance to substrate salinity, presenting less damage to the photosynthetic apparatus and greater superoxide dismutase activity, which may be advantageous under prolonged salt stress conditions. Fri, 27 Mar 2026 00:00:00 GMT https://repositorio.ufra.edu.br/jspui/handle/riufra/2857 2026-03-27T00:00:00Z https://repositorio.ufra.edu.br/jspui/handle/riufra/2849 Título: Respostas ecofisiológicas de pimenta longa (piper hispidinervum c.dc.) submetida a diferentes condições de manejo no município de Igarapé-Açu, PA. Autor(es): SILVA, Enilson Solano Albuquerque Abstract: Aiming to address appropriate management in the cultivation, it was studied, between May/98 and March/99, in field conditions, in the Municipal district of Igarapé-Açu, PA, the water relations, the biochemical responses, biomass production and allocation, and essential oil production in plants of pimenta longa cultivated with and without irrigation. The treatments were: T1 - irrigated and nonfertilized; T2 - irrigated and fertilized; T3 - non-irrigated and non-fertilized; T4 - non-irrigated and fertilized. Starting from the 6" day without the rainfall, alterations were observed on the biophysical variables. In the 15" day of water stress, in the treatments without irrigation, it was observed the largest impact on the variables, where the pre-dawn water potential was reduced from -0.05 MPa to -0,5 MPa, the stomatal resistance increased from approximately 0.3 s.cm” to more than 5.0 s.cm'', at 9:00h a.m, and net photosynthesis was reduced from 20 umol.m?.s", to values around 1.4 umol.m?.s*. After the periods of defiícits, the plants showed recovery capacity, displaying values close to the ones observed in the plants without water stress. lt was observed that in the driest months, there was a reduction in the chlorophyll content, independent of the treatment, being chlorophyll a, more affected. Water stress reduced the contents of total soluble sugars and of potassium, while the protein and phosphorus contents stayed practically constant, during the observation period. In the irrigated plants, potassium contents increased with plants age. Water deficiency affected dry mass production of all plant parts, and it also reduced the number of plants in approximately 30%. Biomass and essential oil productions were reduced by 50%, compared to the irrigated treatments, until the 7" month after planting, when changes in the biomass allocation pattern were noticed in the irrigated treatments. In the 9"" month, with the re-establishment of the rainfall, recovery of plant growth was observed in the non-irrigated treatment. Thus, water deficiency in any phase of the plant development, affects the production of essential oil. Tue, 17 Mar 2026 00:00:00 GMT https://repositorio.ufra.edu.br/jspui/handle/riufra/2849 2026-03-17T00:00:00Z