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Abstract(s)
A proteção dos solos na agricultura tem um papel crucial na mitigação das
alterações climáticas. Na prática da agricultura, sempre que possível, é essencial manter
uma cobertura permanente sobre o solo, utilizando plantas de cobertura. Portugal possui
um clima mediterrânico, com verões quentes e secos e invernos frios e chuvosos, tornando
a implementação de plantas de cobertura de inverno a mais adequada para proteger os
solos durante a estação chuvosa. Plantas do género Trifolium são ideais devido à sua
elevada capacidade de cobertura, resistência a invernos rigorosos e potencial para
adubação verde, realizando associações simbióticas com bactérias diazotróficas que
fixam azoto atmosférico. Este trabalho teve como objetivo avaliar a fixação biológica de
azoto de diferentes estirpes de bactérias fixadoras de azoto em três misturas de espécies
de trevos, visando promover o crescimento das plantas e melhorar a fertilidade do solo.
O ensaio foi conduzido durante 52 dias, em vaso, numa estufa da Escola Superior Agrária
do Instituto Politécnico de Bragança. Bactérias do género Rhizobium e Agrobacterium
foram bioprospetadas de nódulos de trevos do distrito de Bragança e inoculadas em
misturas de sementes de trevos, incluindo uma mistura de duas cultivares de trevo
subterrâneo (Trifolium subterraneum cv. Campeda e Trifolium subterraneum cv.
Woogenellup) e trevos de porte ereto (Trifolium vesiculosum e Trifolium incarnatum).
Foram avaliados o comprimento da parte aérea das plantas, massa seca, teores de
clorofilas e teor de N do solo. Os resultados não mostraram diferença estatística para
massa seca, comprimento da parte aérea e teor de N do solo. No entanto, houve uma
melhoria no teor de clorofila total nos tratamentos com misturas de trevos de porte ereto
inoculados, em comparação com a testemunha. Estes resultados podem ter sido
influenciados pela elevada infestação da planta daninha Chenopodium alba, que não foi
controlada para simular um ambiente de campo. Além disso, a eficiência das estirpes de
bactérias fixadoras de azoto pode variar dependendo das condições específicas do solo e
do clima, sugerindo a necessidade de mais estudos para otimizar a aplicação destas
práticas. É importante continuar a investigar a interação entre diferentes estirpes de
Rhizobium spp. e Agrobacterium spp. com várias espécies de trevos para maximizar a
fixação de azoto e, consequentemente, a saúde e produtividade do solo.
Soil protection is crucial for mitigating climate change in agriculture. For this practice, it is essential to maintain permanent soil cover using cover crops. Portugal has a mediterranean climate, with hot, dry summers and cold, rainy winters, making the implementation of winter cover crops the most suitable for soil protection during the rainy season. Plants of the genus Trifolium are ideal due to their high soil coverage capacity, resistance to harsh winters, and potential for green manuring, forming symbiotic associations with diazotrophic bacteria that fix atmospheric nitrogen. This study aimed to evaluate the nitrogen fixation of different strains of indigenous nitrogen-fixing bacteria in two mixtures of species of clover, aiming to promote plant growth and improve soil fertility. The experiment was conducted for 52 days in pots placed in a greenhouse at the Escola Superior Agrária of the Institute Polytechnic of Bragança. Bacteria of the genera Rhizobium and Agrobacterium were bioprospected from clover nodules in the Bragança district and inoculated into mixtures of clover seeds, including subterranean clover (Trifolium subterraneum cv. Campeda e Trifolium subterraneum cv. Woogenellup) and erect-growing clovers (Trifolium vesiculosum e Trifolium incarnatum). The length of the plant aerial parts, dry mass, chlorophyll content, and soil N content were evaluated. The results showed no statistical difference for dry mass, aerial part length, and soil N content. However, there was an improvement in total chlorophyll content in the surface clover mix treatments when inoculated compared to the control. These results may have been influenced by the high infestation of the weed Chenopodium alba, which was not controlled to simulate a field environment. Furthermore, the efficiency of nitrogen-fixing bacterial strains can vary depending on specific soil and climate conditions, suggesting the need for further studies to optimize the application of these practices. It is important to continue investigating the interaction between different strains of Rhizobium spp. and Agrobacterium spp. with various clover species to maximize nitrogen fixation and, consequently, soil health and productivity.
Soil protection is crucial for mitigating climate change in agriculture. For this practice, it is essential to maintain permanent soil cover using cover crops. Portugal has a mediterranean climate, with hot, dry summers and cold, rainy winters, making the implementation of winter cover crops the most suitable for soil protection during the rainy season. Plants of the genus Trifolium are ideal due to their high soil coverage capacity, resistance to harsh winters, and potential for green manuring, forming symbiotic associations with diazotrophic bacteria that fix atmospheric nitrogen. This study aimed to evaluate the nitrogen fixation of different strains of indigenous nitrogen-fixing bacteria in two mixtures of species of clover, aiming to promote plant growth and improve soil fertility. The experiment was conducted for 52 days in pots placed in a greenhouse at the Escola Superior Agrária of the Institute Polytechnic of Bragança. Bacteria of the genera Rhizobium and Agrobacterium were bioprospected from clover nodules in the Bragança district and inoculated into mixtures of clover seeds, including subterranean clover (Trifolium subterraneum cv. Campeda e Trifolium subterraneum cv. Woogenellup) and erect-growing clovers (Trifolium vesiculosum e Trifolium incarnatum). The length of the plant aerial parts, dry mass, chlorophyll content, and soil N content were evaluated. The results showed no statistical difference for dry mass, aerial part length, and soil N content. However, there was an improvement in total chlorophyll content in the surface clover mix treatments when inoculated compared to the control. These results may have been influenced by the high infestation of the weed Chenopodium alba, which was not controlled to simulate a field environment. Furthermore, the efficiency of nitrogen-fixing bacterial strains can vary depending on specific soil and climate conditions, suggesting the need for further studies to optimize the application of these practices. It is important to continue investigating the interaction between different strains of Rhizobium spp. and Agrobacterium spp. with various clover species to maximize nitrogen fixation and, consequently, soil health and productivity.
Description
Keywords
Rhizobium Agrobacterium Trevo Crescimento