Inibição do desenvolvimento de sclerotinia sclerotiorum em sementes de feijão com o uso de óleos essenciais e fungos antagonistas
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Data
2022-01-27
Autores
Chaga, Larissa Moreira
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Universidade Estadual Paulista (Unesp)
Resumo
O feijoeiro-comum é suscetível ao mofo branco, doença causada por Sclerotinia sclerotiorum e que resulta em redução da produtividade devido à morte das sementes e das plântulas, além de poder originar plantas infectadas. O seu controle envolve uma série de medidas integradas, incluindo o tratamento de sementes. A pesquisa teve como objetivo avaliar o efeito do tratamento sementes de feijão com os óleos essenciais (OE) de cravo–da–índia e pimenta–preta (Capítulo I) e com os antagonistas Clonostachys rósea e Trichoderma spp. (Capítulo II) sobre a incidência de S. sclerotiorum nas sementes e a qualidade fisiológica das sementes tratadas. No primeiro capítulo, inicialmente, os OE foram adicionados ao meio de cultura BDA para verificar o seu efeito in vitro sobre o desenvolvimento fúngico. BDA + fungicida tiofanato metílico + fluazinam e BDA puro constituíram os tratamentos testemunhas. O OE de cravo-da-índia promoveu 100% de inibição no crescimento fúngico, com desempenho igual ao do fungicida. O OE de pimenta-preta apresentou potencial de controle in vitro, porém com menor eficiência. Em seguida, as sementes foram tratadas com os OEs, para avaliar seus efeitos na qualidade sanitária e fisiológica das sementes. Sementes tratadas com tiofanato metílico + fluazinam (750 ppm), sementes não inoculadas e sementes inoculadas, ambas sem tratamento, foram incluídas no experimento. A sanidade foi avaliada pelo método do papel filtro. Não houve incidência do patógeno nas sementes tratadas com OE e fungicida. Para avaliar a qualidade fisiológica, foram realizados testes de germinação de vigor (primeira contagem de germinação - PCG). Para avaliar o efeito do tratamento de sementes no desevolvimento das plântulas, o índice de velocidade de emergência (IVE) em substrato e o comprimento e massa fresca e seca da parte aérea e radicular das plântulas foram avaliados em casa-de-vegetação. Não houve diferença entre as sementes inoculadas e não inoculadas, ambas sem tratamento, para todas as variáveis estudadas. Com exceção do OE de cravo a 0,75%, que interferiu negativamente na PCG e germinação, os demais tratamentos não tiverem efeito no potencial fisiológico das sementes. Com relação aos testes conduzidos em substrato, o OE de cravo-da-índia mostrou-se fitóxico nas concentrações avaliadas, impedindo a germinação das sementes. O OE de pimenta-preta interferiu negativamente no IVE, mas à concentração de 0,75%, proporcionou desenvolvimento de plântulas satisfatório. No segundo capítulo, o experimento de biocontrole foi iniciado por uma etapa in vitro, para avaliar a ação dos antagonistas sobre S. sclerotiorum. Os dois antagonistas tiveram efeito inibitório sobre o patógeno, com maior ação supressora de C. rosea. Em seguida, foi feito o tratamento de sementes com os antagonistas e o fungicida tiofanato metílico + fluazinam. Sementes inoculadas e não inoculadas, ambas sem tratamento, foram incluídas no experimento. Foram analisadas a sanidade e a qualidade fisiológica das sementes conforme descrito para os experimentos de OE. Os antagonistas não controlaram o patógeno nas sementes. De maneira geral, o tratamento biológico não interferiu na qualidade fisiológica das sementes e no desenvolvimento das plântulas. O OE de pimenta-preta mostrou potencial de uso no tratamento de sementes para controle de S. sclerotiorum, porém, mais estudos são necessários para melhorar a eficiência do tratamento no que diz respeito à qualidade fisiológica. Com relação ao tratamento biológico, apesar do efeito inibitório in vitro, os antagonistas não controlaram o patógeno nas sementes, sugerindo a necessidade de ajustes na aplicação do tratamento.
Common bean is susceptible to white mold disease, which is caused by Sclerotinia sclerotiorum. White mold results in reduced yield due to seeds and seedlings death, besides originating infected plants. This disease control involves a series of integrated measures, including seed treatment. This research aimed to evaluate the effect of bean seeds treatment with clove and black pepper essential oils (EOs) (Chapter I), as well as Clonostachys rosea e Trichoderma spp. antagonists (Chapter II) on S. sclerotiorum incidence in the seeds and on their physiological quality. In the first chapter, EOs were added to the PDA culture medium to verify their in vitro effect on fungal development. PDA with thiophanate methyl + fluazinam fungicide and pure PDA constituted the control treatments. Clove EO inhibited 100% of fungal growth, which was similar to the fungicide performance. Black pepper EO showed in vitro control potential, but with lower efficiency. Then, the seeds were treated with EOs in order to evaluate their effects on the seeds sanitary and physiological qualities. Seeds treated with thiophanate methyl + fluazinam (750 ppm), untreated uninoculated seeds and untreated inoculated seeds were included in the experiment. Seed sanitary quality was evaluated with blotter test. There was no pathogen incidence in the seeds treated with EO and fungicide. Aiming to evaluate the seed physiological quality, germination and vigor (first germination count - PCG) tests were carried out. In order to evaluate the seed treatments effect on seedling development, emergence speed index (IVE), root and shoot length, as well as root and shoot fresh and dry mass were studied in greenhouse experiments There was no difference between untreated inoculated and untreated uninoculated seeds for all variables studied. Except for clove EO at 0.75%, which negatively interfered with PCG and germination, the other treatments had no effect on the seeds physiological quality. Regarding the tests carried out in substrate, clove EO proved to be phytotoxic at the concentrations evaluated, preventing seed germination. Black pepper EO had a negative effect on the IVE, however, at a concentration of 0.75%, it provided satisfactory seedling development. In the second chapter, the biocontrol experiment started with an in vitro phase, in order to evaluate the antagonists action on S. sclerotiorum development. Both antagonists had an inhibitory effect on the pathogen, on which C. rosea presented a higher suppressive action. Then, the seeds were treated with antagonists and thiophanate methyl + fluazinam fungicide. Untreated inoculated and untreated uninoculated seeds were included in the experiment. Seeds sanitary and physiological qualities were evaluated as previously described. The antagonists did not control the pathogen in the seeds. In general, the biological treatment did not interfere either seeds physiological quality or in the seedlings development. Black pepper EO showed promising use for seed treatment to control S. sclerotiorum. However, more studies are needed to improve this treatment efficiency regarding the physiological quality. Concerning the biological treatment, despite the antagonists in vitro inhibitory effect, they did not control the pathogen in the seeds, suggesting that adjustments in this treatment application are necessary.
Common bean is susceptible to white mold disease, which is caused by Sclerotinia sclerotiorum. White mold results in reduced yield due to seeds and seedlings death, besides originating infected plants. This disease control involves a series of integrated measures, including seed treatment. This research aimed to evaluate the effect of bean seeds treatment with clove and black pepper essential oils (EOs) (Chapter I), as well as Clonostachys rosea e Trichoderma spp. antagonists (Chapter II) on S. sclerotiorum incidence in the seeds and on their physiological quality. In the first chapter, EOs were added to the PDA culture medium to verify their in vitro effect on fungal development. PDA with thiophanate methyl + fluazinam fungicide and pure PDA constituted the control treatments. Clove EO inhibited 100% of fungal growth, which was similar to the fungicide performance. Black pepper EO showed in vitro control potential, but with lower efficiency. Then, the seeds were treated with EOs in order to evaluate their effects on the seeds sanitary and physiological qualities. Seeds treated with thiophanate methyl + fluazinam (750 ppm), untreated uninoculated seeds and untreated inoculated seeds were included in the experiment. Seed sanitary quality was evaluated with blotter test. There was no pathogen incidence in the seeds treated with EO and fungicide. Aiming to evaluate the seed physiological quality, germination and vigor (first germination count - PCG) tests were carried out. In order to evaluate the seed treatments effect on seedling development, emergence speed index (IVE), root and shoot length, as well as root and shoot fresh and dry mass were studied in greenhouse experiments There was no difference between untreated inoculated and untreated uninoculated seeds for all variables studied. Except for clove EO at 0.75%, which negatively interfered with PCG and germination, the other treatments had no effect on the seeds physiological quality. Regarding the tests carried out in substrate, clove EO proved to be phytotoxic at the concentrations evaluated, preventing seed germination. Black pepper EO had a negative effect on the IVE, however, at a concentration of 0.75%, it provided satisfactory seedling development. In the second chapter, the biocontrol experiment started with an in vitro phase, in order to evaluate the antagonists action on S. sclerotiorum development. Both antagonists had an inhibitory effect on the pathogen, on which C. rosea presented a higher suppressive action. Then, the seeds were treated with antagonists and thiophanate methyl + fluazinam fungicide. Untreated inoculated and untreated uninoculated seeds were included in the experiment. Seeds sanitary and physiological qualities were evaluated as previously described. The antagonists did not control the pathogen in the seeds. In general, the biological treatment did not interfere either seeds physiological quality or in the seedlings development. Black pepper EO showed promising use for seed treatment to control S. sclerotiorum. However, more studies are needed to improve this treatment efficiency regarding the physiological quality. Concerning the biological treatment, despite the antagonists in vitro inhibitory effect, they did not control the pathogen in the seeds, suggesting that adjustments in this treatment application are necessary.
Descrição
Palavras-chave
Controle alternativo, Controle biológico, Mofo branco do feijoeiro, Clonostachys rosea, Trichoderma spp., Patologia de sementes, Alternative control, Biological control, Bean white mold, Seed pathology