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Controlo biológico de doenças do solo em plantas cultivadas, através da utilização de compostos de resíduos orgânicos enriquecidos com antagonistas
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Abstract(s)
A compostagem valoriza resíduos orgânicos transformando-os em compostados ou compostos, com importantes aplicações agrícolas. Durante a compostagem, a presença de quitina - o principal componente da parede celular dos fungos - favorece a ocorrência de microrganismos com capacidade de a degradar, desenvolvendo a capacidade de controlo de doenças causadas por fungos do solo - capacidade supressiva - observada pelo uso desses compostos.
Para avaliar a influência da quitina na capacidade supressiva produziram-se dois compostos com resíduos agroindustriais: P1 (laranja, bagaço de uva e aparas de relva) e P2 (os mesmos que P1, acrescidos de resíduos da produção de cogumelos), em três compostagens realizadas em anos sucessivos. Os microrganismos isolados nos compostos foram identificados morfológica e molecularmente, e testou-se a sua capacidade antagonista contra doenças do solo, in vitro. Os compostos obtidos foram testados in vivo, em Agrostis stolonifera L. e em Stevia rebaudiana Bertoni, cultivadas nos compostos e em turfa comercial (P). Nos compostos obtidos foram isoladas 190 espécies de fungos, 31 das quais manifestaram capacidade antagonista, 14 espécies em P1 e 17 em P2. Nos ensaios in vitro contra Sclerotium rolfsii, Clarireedia spp. e Rhizoctonia solani, T. atroviride foi o antagonista com maior taxa de inibição. Nos ensaios in vivo usando os compostos como substratos, o controlo de Clarireedia spp. foi mais eficaz com P1, enquanto o controlo de R. solani e S. rolfsii foi mais eficaz com P2. Amostras dos substratos (P1, P2 e P) foram submetidas a tratamento térmico (P1t, P2t e Pt) e enriquecimento (E) com o antagonista mais eficiente identificado in vitro: T. atroviride (P1E, P2E, P1tE, P2tE, PE e PtE). A capacidade supressiva dos diferentes substratos foi testada logo após a sua obtenção e depois de 6 e 12 meses de armazenamento.
Na relva, obteve-se um maior controlo das doenças utilizando compostos enriquecidos, sendo P1E o mais eficaz contra Clarireedia spp. e P2E contra R. solani. Os compostos mantiveram a capacidade supressiva ao longo do tempo, sobretudo os enriquecidos, os quais proporcionaram os melhores resultados de proteção após 6 meses de armazenamento.
Neste trabalho, verificou-se que resíduos agroindustriais podem ser transformados em produtos com capacidade de reduzir a aplicação de fitofármacos sintéticos, mantendo esta capacidade por algum tempo e contribuindo para uma maior sustentabilidade e circularidade na agricultura.
Composting is a process by which we increase the value of organic wastes by transforming them into compost, which has important agricultural applications. During composting, the presence of chitin favours the occurrence of microorganisms capable of degrading it, developing the ability to control diseases caused by soil fungi - suppressive capacity - observed using these composts. To evaluate the influence of chitin on the suppressive capacity, two composts were produced with agro-industrial residues: P1 (orange fruit waste, grape marc and grass clippings) and P2 (P1 with added residues from mushroom production), with three composting processes in three successive years. The microorganisms isolated in the composts were identified both morphologically and molecularly, and their antagonistic capacity against soil diseases, in vitro. The obtained composts were tested in vivo, in Agrostis stolonifera L. and in Stevia rebaudiana Bertoni, cultivated in composts and in a commercial peat (P). In the composts, 190 species of fungi were isolated, 31 of which had antagonist capacity, 14 species in P1 and 17 in P2. During in vitro testing against Sclerotium rolfsii, Clarireedia spp. and Rhizoctonia solani, the antagonist with the highest inhibition rate was T. atroviride. During in vivo testing, control of Clarireedia spp. was more effective with P1, while that of R. solani and S. rolfsii was more effective with P2. Substrate samples (P, P1 and P2) were subjected to heat treatment (P1t, P2t and Pt) and enrichment (E) with the most efficient antagonist in vitro: T. atroviride (P1E, P2E, PE, P1tE, P2tE and PtE). The suppressive capacity of the different substrats was tested after 0, 6 and 12 months of storage. In turfgrass, greater disease control was obtained with enriched composts, with P1E being the most effective against Clarireedia spp. and P2E against R. solani. The composts maintained their suppressive capacity over time, especially the enriched ones, providing the best results after 6 months of storage. In this work, it was found it is possible to convert agro-industrial residues into products capable of reducing the application of synthetic phytopharmaceuticals and the suppressive capacity is kept for some time, contributing to sustainability and circularity of agriculture.
Composting is a process by which we increase the value of organic wastes by transforming them into compost, which has important agricultural applications. During composting, the presence of chitin favours the occurrence of microorganisms capable of degrading it, developing the ability to control diseases caused by soil fungi - suppressive capacity - observed using these composts. To evaluate the influence of chitin on the suppressive capacity, two composts were produced with agro-industrial residues: P1 (orange fruit waste, grape marc and grass clippings) and P2 (P1 with added residues from mushroom production), with three composting processes in three successive years. The microorganisms isolated in the composts were identified both morphologically and molecularly, and their antagonistic capacity against soil diseases, in vitro. The obtained composts were tested in vivo, in Agrostis stolonifera L. and in Stevia rebaudiana Bertoni, cultivated in composts and in a commercial peat (P). In the composts, 190 species of fungi were isolated, 31 of which had antagonist capacity, 14 species in P1 and 17 in P2. During in vitro testing against Sclerotium rolfsii, Clarireedia spp. and Rhizoctonia solani, the antagonist with the highest inhibition rate was T. atroviride. During in vivo testing, control of Clarireedia spp. was more effective with P1, while that of R. solani and S. rolfsii was more effective with P2. Substrate samples (P, P1 and P2) were subjected to heat treatment (P1t, P2t and Pt) and enrichment (E) with the most efficient antagonist in vitro: T. atroviride (P1E, P2E, PE, P1tE, P2tE and PtE). The suppressive capacity of the different substrats was tested after 0, 6 and 12 months of storage. In turfgrass, greater disease control was obtained with enriched composts, with P1E being the most effective against Clarireedia spp. and P2E against R. solani. The composts maintained their suppressive capacity over time, especially the enriched ones, providing the best results after 6 months of storage. In this work, it was found it is possible to convert agro-industrial residues into products capable of reducing the application of synthetic phytopharmaceuticals and the suppressive capacity is kept for some time, contributing to sustainability and circularity of agriculture.
Description
Keywords
Compostagem Supressividade Agrostis stolonifera Trichoderma atroviride Rhizoctonia solani Clarireedia spp. Sclerotium rolfsii