https://repositorio.ufu.br/handle/123456789/18943 Wed, 15 Jul 2026 22:46:08 GMT 2026-07-15T22:46:08Z https://repositorio.ufu.br/handle/123456789/48806 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. Wed, 03 Jun 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48806 2026-06-03T00:00:00Z https://repositorio.ufu.br/handle/123456789/48768 Title: Parâmetros genéticos e seleção de populações F2 provenientes de cruzamentos simples e duplos de alfaces biofortificadas e tropicalizadas Abstract: Lettuce is one of the most widely consumed leafy vegetables worldwide, with continuous cultivation throughout the year. In Brazil, its performance is limited by tropical conditions, especially high temperatures that induce early bolting, compromising commercial and nutritional quality. At the same time, the demand for functional foods is increasing, driving research focused on the biofortification of lettuce with bioactive compounds through genetic improvement. This study aimed to estimate genetic parameters in F2 populations derived from single and double hybrids of biofortified and tropicalized lettuces, with the goal of selecting outstanding populations. Fifteen F2 populations and three commercial cultivars were evaluated for agronomic traits and bioactive compound content. The hybrid populations showed superior performance compared to the controls, particularly in number of leaves, delayed bolting, and higher levels of chlorophyll, carotenoids, and anthocyanins, with bioactive compounds exhibiting medium to high heritability. Genetic analysis revealed CVG/CVA values close to 1 for Chlorophyll a (0.93), Carotenoids (0.74), and Anthocyanins (0.70), indicating the feasibility of genetic selection. The results confirmed that bioactive compound content in lettuce is determined by genetic factors, enabling the identification and selection of populations for biofortification and tropicalization, contributing to the development of cultivars adapted to Brazilian edaphoclimatic conditions. Fri, 26 Sep 2025 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48768 2025-09-26T00:00:00Z https://repositorio.ufu.br/handle/123456789/48756 Title: Parâmetros genéticos, estratégias de seleção e diversidade genética em genótipos de soja Abstract: This thesis is divided into three chapters. In the first chapter, the objective was to study the combinatorial capacity of three parental lines through diallel crosses, using Griffing's method I (1956). Additive effects were more significant than non-additive effects for all traits evaluated. The TMG 801 parent contributed to an increase in most of traits evaluated, while the BRSGO 7560 parent contributed to a decrease in those traits. The most promising cross for shortening the growing season was BRSGO 7560 x TMG 801, while the cross UFUS 7415 x TMG 801 stood out for increasing grain yield. The combination that presented the most favorable values for cycle reduction and increased grain production was TMG 801 x BRSGO 7560. In the second chapter, the objective was to develop three soybean populations and estimate genetic parameters and breeding gains, with the aim of shortening the growing season and increasing grain yield, through the analysis of generations. Overall, for each cross, the means for agronomic and production traits in the F2, RC1, and RC2 generations were intermediate between those of their parents, and the values for the backcrosses were close to those of their respective parent. The heritability estimates (%) for the BRSGO 7560 x TMG 801 cross were: NDF (114.66%), NNTo (78.92%), NTV (102.21%), and PG (69.02%); in the combination TMG 7161 RR x UFUS 7415 they were: NNTo (107.2%), NTV (94.06%), and PG (104.91%); and in the combination TMG 801 x UFUS 7415 they were: NDF (94.84%), NDM (168.40%), NTV (71.05%), and PG (70.69%). The greatest gains per selection for cycle reduction (NDM) were obtained in the TMG 801 x UFUS 7415 cross (-21.09%), while, for increased grain production (g), the greatest gains were observed in the TMG 7161 RR x UFUS 7415 cross (97.88%). In the third chapter, the objective was to evaluate different strategies for selecting early-cycle, high-grain-yielding progenies using direct and indirect selection indices, as well as to conduct studies of genetic diversity using different clustering techniques, with the aim to identify divergent parents. Thirty progenies, F6-F7 and F7-F8, were evaluated in two growing seasons, in addition to four control lines (UFUS 7415, UFUS Tupi, UFUS 7910, and UFUS MLX). Genetic variability was detected among the evaluated progenies at a 1% or 5% probability level using the F-test for all evaluated traits. Direct and indirect selection provided the greatest genetic gains. Among the selection índices, the highest total genetic gain were obtained using the Mulamba and Mock indices. The NDM and NDF traits contributed most to determining genetic diversity. The Tocher, UPGMA, and canonical variable analysis methods clusteres the genotypes in a similar manner, forming five groups in the summer crop and four groups in the winter crop. The S128P3 and S128P4 progenies presented short cycle and high yield, desirable characteristics for use in crossbreeding with divergent genotypes. Wed, 25 Feb 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48756 2026-02-25T00:00:00Z https://repositorio.ufu.br/handle/123456789/48432 Title: Análise dialélica de genitores de soja visando precocidade, produtividade e teores de proteína e óleo Abstract: The careful selection of parents through combining ability methods, as well as the estimation of genetic parameters and correlations, constitute fundamental tools in breeding programs to identify segregating populations with high genetic potential and to ensure the development of superior soybean cultivars. This thesis was divided into three chapters in the article format. The first chapter aimed to evaluate the combining ability of five soybean parents for agronomic traits and protein and oil contents, with the objective of identifying promising combinations for the extraction of superior lines. The trials were conducted in Uberlândia (MG) in the 2022/23 (F3 generation) and 2023/24 (F4 generation) growing seasons, involving the parents UFUS 7010, UFUS 7101, IAC Foscarin-31, TMG 803, and BRS 511. Through diallel analysis, it was concluded that the parents IAC Foscarin-31 and BRS 511 contribute to earlier maturity and higher protein content, while TMG 803 favors productivity, and UFUS 7101 increases oil content. The most promising combinations for earliness and grain yield were TMG 803 × BRS 511 and IAC Foscarin-31 × TMG 803, whereas the combination IAC Foscarin-31 × BRS 511 stood out for increasing protein content. The second chapter aimed to estimate the combining ability of nine soybean parents through a partial diallel and to identify promising segregating combinations for agronomic traits. The trials were conducted in Uberlândia-MG in the 2023/24 (F2) and 2024/25 (F3) growing seasons, using a partial diallel between five elite genotypes (UFUS 7010, UFUS 7101, UFUS 7201, UFUS 7910, and UFUS 8401) and four genotypes serving as sources of resistance to the soybean cyst nematode (TMG 2381 IPRO, TMG 4182, BRS 7380 RR, and BRS 7581 RR). Additive gene effects predominated, indicating that the parents UFUS 7201, UFUS 8401, TMG 2381 IPRO, and TMG 4182 provided the greatest gains for yield and number of pods. The most promising combinations for obtaining superior genotypes with high productive potential were UFUS 7101 × TMG 2381 IPRO, UFUS 7910 × TMG 2381 IPRO, and UFUS 7910 × TMG 4182. The third chapter aimed to estimate genetic parameters in segregating populations and to select those with the highest potential for earliness, grain yield, and protein and oil content. Eight segregating populations and six parents were evaluated in the early generations (F2, F3, and F4), conducted in Uberlândia (MG) between the 2021/22 and 2023/24 growing seasons. The analyses showed significant genetic variability and high-magnitude heritabilities for cycle and biochemical quality. The populations UFUS 4 (for earliness and oil), UFUS 7 (for protein), and UFUS 8 (for productivity, medium cycle, and oil) stood out as the most promising for the extraction of superior genotypes. In all experiments, phenological, agronomic, yield components, and grain biochemical quality traits were evaluated. Fri, 13 Feb 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48432 2026-02-13T00:00:00Z