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Abstract(s)
O estudo de técnicas agrícolas sustentáveis tornou-se fundamental face ao aumento da população e ao crescente desgaste dos recursos naturais. Assim, esta tese visa a integração de leguminosas num contexto de agricultura sustentável a nível europeu, utilizando para tal uma série de estudos de caso nos quais o papel da ervilha, da soja e da fava foi avaliado. O primeiro estudo de caso analisou culturas intercalares de cevada e ervilha e de que forma estas últimas podem afetar a nutrição da cevada, bem como que consequência traz a limitação de ferro (Fe) no caso da ervilha. Na cevada, destaca-se o aumento significativo (p<0.05) da concentração de Fe, magnésio (Mg), fósforo (P), cálcio (Ca) e zinco (Zn), quando intercalada com ervilha. Posteriormente, a limitação de Fe induzida durante o crescimento hidropónico da ervilha gerou o aumento (p<0.05) da concentração de Fe ao nível da parte aérea da planta enquanto que a concentração de Fe (p<0.0001), boro (B) (p<0.01) e Mg (p<0.05) diminuiu ao nível da raíz. Nas mesmas condições de limitação, a expressão da enzima Fe redutase foi de 0.022 μmol Fe/g FW-1 h-1, diminuindo 67% relativamente a uma situação de administração normal de Fe (100 μM Fe3+-EDDHA). Mais ainda, o gene nitrito redutase 1 (NIR1) aumentou (p<0.05) a sua expressão ao nível da raíz e da parte aérea da planta em situação de carência. O segundo estudo permitiu a análise do conteúdo mineral de favas previamente selecionadas pela sua maior percentagem de azoto (N), tendo em conta propriedades morfológicas do grão e parâmetros de rendimento. As variedades de fava com teor de N mais elevadas não foram indicativas de um perfil mineral melhorado e apresentaram-se heterogéneas dentro da mesma variedade. O terceiro incluiu a caraterização de estirpes de bactérias presentes em três inóculos comerciais destinados à produção de soja (Euralis, LegTech, RhizLiq), bem como avaliou o impacto da sua aplicação. A identificação molecular das estirpes Bradyrhizobium japonicum e Bradyrhizobium diazoefficiens nos inóculos testados mostrou que a sua dupla combinação com micorriza arbuscular é a mais eficaz para a maximização dos efeitos da inoculação na soja. Por último, o quarto estudo compreendeu a análise quantitativa da produção de hormona vegetal ácido 3-índole-acético (IAA) por parte de isolados de Rhizobium leguminosarum bv. viciae, relacionando a referida produção com a biomassa da ervilha de onde surgiram os isolados. Foi ainda efetuada uma análise qualitativa em placa da solubilização de fosfato nas mesmas amostras. As análises funcionais de rhizobia de ervilha demonstraram uma relação não significativa (R2=0,1324) entre a produção de hormona vegetal e a biomassa de cada uma das amostras, assim como também não ocorreu solubilização de fosfato na maioria dos casos. Globalmente, estes estudos contribuem para o desenvolvimento da literatura científica nesta área, confirmando o papel das leguminosas em técnicas agrícolas sustentáveis de melhoria da qualidade nutricional e agronómica das culturas.
The study of sustainable agricultural techniques has become essential with the emergence of population growth and the depletion of natural resources. In this way, this thesis aims to integrate legumes in a context of sustainable agriculture at a european level, using for that purpose a set of case studies in which the role of pea, soybean and faba bean was evaluated. The first case study examined the intercrop of barley and pea and how the latter can affect barley nutrition, as well as the consequence of limiting iron (Fe) in the case of pea. A significant increase (p<0.05) in the concentration of Fe, magnesium (Mg), phosphorus (P), calcium (Ca) and zinc (Zn) was observed in barley when intercropped with pea. The Fe limitation induced during hydroponic growth of pea increased Fe concentration (p<0.05) in the shoot, while the concentration of Fe (p<0.0001), boron (B) (p<0.01) and Mg (p<0.05) decreased at the root level. Under the same limiting conditions, the Fe reductase enzyme expression was of 0.022 μmol Fe/g FW-1 h-1, which was decreased 67% when compared to standard Fe administration (100 μM Fe3+-EDDHA). Moreover, the expression of the gene nitrite reductase 1 (NIR1) increased (p<0.05) in the root and shoot of the plants in Fe deficiency. The second study allowed the mineral content analysis of previously selected faba beans by their higher percentage of nitrogen (N), considering the grain morphological properties and yield parameters. The faba varieties with higher N content were not indicative of an improved mineral profile and were heterogeneous within the same variety. The third included the characterization of bacterial strains present in three commercial inoculums destined to soybean production (Euralis, LegTech, RhizLiq), as well as the impact of its application. Molecular identification of the strains Bradyrhizobium japonicum and Bradyrhizobium diazoefficiens in the inoculums tested showed that their double combination with arbuscular mycorrhiza is the most effective for maximizing the effects of soybean inoculation. Finally, the fourth study comprised the quantitative analysis of the production of 3-indole-acetic acid (IAA) hormone by Rhizobium leguminosarum bv. viciae isolates, relating this production to the pea biomass. A qualitative plate analysis of the phosphate solubilization of the previous isolates was also carried out. Functional analyses of pea rhizobia showed a non-significant relationship (R2=0.1324) between the hormone production and the samples biomass, as well as it did not occur phosphate solubilization in most cases. Globally, these studies contribute to the development of scientific literature in this area, confirming the role of legumes in sustainable agricultural techniques for improving the nutritional and agronomic quality of crops.
The study of sustainable agricultural techniques has become essential with the emergence of population growth and the depletion of natural resources. In this way, this thesis aims to integrate legumes in a context of sustainable agriculture at a european level, using for that purpose a set of case studies in which the role of pea, soybean and faba bean was evaluated. The first case study examined the intercrop of barley and pea and how the latter can affect barley nutrition, as well as the consequence of limiting iron (Fe) in the case of pea. A significant increase (p<0.05) in the concentration of Fe, magnesium (Mg), phosphorus (P), calcium (Ca) and zinc (Zn) was observed in barley when intercropped with pea. The Fe limitation induced during hydroponic growth of pea increased Fe concentration (p<0.05) in the shoot, while the concentration of Fe (p<0.0001), boron (B) (p<0.01) and Mg (p<0.05) decreased at the root level. Under the same limiting conditions, the Fe reductase enzyme expression was of 0.022 μmol Fe/g FW-1 h-1, which was decreased 67% when compared to standard Fe administration (100 μM Fe3+-EDDHA). Moreover, the expression of the gene nitrite reductase 1 (NIR1) increased (p<0.05) in the root and shoot of the plants in Fe deficiency. The second study allowed the mineral content analysis of previously selected faba beans by their higher percentage of nitrogen (N), considering the grain morphological properties and yield parameters. The faba varieties with higher N content were not indicative of an improved mineral profile and were heterogeneous within the same variety. The third included the characterization of bacterial strains present in three commercial inoculums destined to soybean production (Euralis, LegTech, RhizLiq), as well as the impact of its application. Molecular identification of the strains Bradyrhizobium japonicum and Bradyrhizobium diazoefficiens in the inoculums tested showed that their double combination with arbuscular mycorrhiza is the most effective for maximizing the effects of soybean inoculation. Finally, the fourth study comprised the quantitative analysis of the production of 3-indole-acetic acid (IAA) hormone by Rhizobium leguminosarum bv. viciae isolates, relating this production to the pea biomass. A qualitative plate analysis of the phosphate solubilization of the previous isolates was also carried out. Functional analyses of pea rhizobia showed a non-significant relationship (R2=0.1324) between the hormone production and the samples biomass, as well as it did not occur phosphate solubilization in most cases. Globally, these studies contribute to the development of scientific literature in this area, confirming the role of legumes in sustainable agricultural techniques for improving the nutritional and agronomic quality of crops.
Description
Keywords
Bactérias promotoras de crescimento vegetal (BPCV) Culturas intercalares Inoculantes Leguminosas Nutrição Rhizobia Inoculants Intercrop Legumes Nutrition Plant growth promoting rhizobia (PGPR)