Jayne Deboni da Veiga

Soybean is one of the most important commodities in the world, and is affected by several phytopathogens, such as the fungus Macrophomina phaseolina , which can occur at all stages of development, causing significant losses in production. The use of different cultural, chemical and genetic control strategies has shown low efficiency against this phytopathogen. Thus, the objective of this study was to evaluate the use of Trichoderma asperellum , T. endophyticum and T. harzianum in seed treatment to control M. phaseolina and promote plant growth. Healthy seeds inoculated with M. phaseolina were treated with the three Trichoderma species, the plant growth regulator Stimulate®, an insecticide based on Thiamethoxam and combinations of Trichoderma species with Stimulate® or Thiamethoxam. The antagonistic capacity of Trichoderma species against M. phaseolina and their compatibility with Stimulate® and Thiamethoxam, germination and seedling vigor, growth and dry biomass of plants were evaluated. Trichoderma species showed antagonism against M. phaseolina , especially T. endophyticum . In vitro , Stimulate® reduced the growth of T. endophyticum and T. harzianum , while Thiamethoxam reduced the growth of T. harzianum . M. phaseolina reduced approximately 80% of soybean seed germination. The three Trichoderma species increased germination and vigor of infected seeds. In healthy seeds, T. harzianum reduced germination, while T. endophyticum combined with Stimulate® increased seedling vigor. These results show that T. endophyticum , T. harzianum and T. asperellum are effective in treating seeds infected with M. phaseolina , and the use of T. harzianum isolate CCT 7589 is not recommended for the treatment of healthy soybean seeds.

Soybean is one of the main agricultural commodities, and its productivity is limited by several diseases, such as anthracnose, which is caused by a complex of fungal species, with Colletotrichum truncatum being the most prevalent. Management is mainly carried out through chemical seed treatment. However, a reduction in the sensitivity of C. truncatum to fungicides was observed. Therefore, it is extremely important to search for products that are effective in controlling the disease. The objectives of this study were to evaluate the efficacy of commercial formulations of copper, potassium, manganese, and zinc phosphites in the treatment of soybean seeds infected by C. truncatum, as well as their direct fungitoxicity and ability to induce soybean defense mechanisms. For this purpose, seeds inoculated with C. truncatum were subjected to phosphites and a fungicide (carbendazim + thiram). The seeds were exposed to germination, health, and vigor tests. Fungal toxicity and the ability of phosphites to induce defense through the activities of catalase, peroxidase, and superoxide dismutase enzymes, as well as the levels of lignin and total soluble phenols, were also evaluated. Mn and Zn phosphites showed direct toxicity to C. truncatum and were as effective as the fungicide (carbendazim + thiram) in treating soybean seeds infected by the fungus. Mn phosphite induced the production of catalase (CAT), peroxidase (POX) and lignin, while Zn phosphite increased the production of CAT and POX. These results demonstrate the efficacy of Mn and Zn phosphites in controlling C. truncatum in infected soybean seeds, their direct toxic action, and their ability to induce resistance.

Soybean is one of the main agricultural commodities, and its productivity is limited by several diseases, such as anthracnose, which is caused by a complex of fungal species, with Colletotrichum truncatum being the most prevalent. Management is mainly carried out through chemical seed treatment. However, a reduction in the sensitivity of C. truncatum to fungicides was observed. Therefore, it is extremely important to search for products that are effective in controlling the disease. The objectives of this study were to evaluate the efficacy of commercial formulations of Cu, K, Mn and Zn phosphites in the treatment of soybean seeds infected by C. truncatum and their ability to induce defense mechanisms against the fungus. For this purpose, seeds inoculated with C. truncatum were treated with phosphites and a fungicide (carbendazim + thiram). The seeds were subjected to germination, health and vigor tests. Fungal toxicity and the ability of phosphites to induce defense through the activities of catalase, peroxidase and superoxide dismutase enzymes, as well as the levels of lignin and total soluble phenols, were also evaluated. Mn and Zn phosphites were toxic to C. truncatum and effective in controlling anthracnose in infected soybean seeds, showing no difference in relation to the fungicide. Mn phosphite induced the production of CAT, POX and lignin, while Zn phosphite increased the production of CAT and POX. These results demonstrate the effectiveness of Mn and Zn phosphites in controlling anthracnose in infected soybean seeds, their direct toxic action and their ability to induce defense mechanisms.

A termoterapia é uma medida de controle utilizada para erradicação de patógenos em sementes, no entanto, é capaz de ocasionar danos ao vigor e germinação das sementes. Com isso, através deste estudo, objetivou-se avaliar a germinação e vigor e a incidência de patógenos de sementes salvas de arroz, submetidas a termoterapia, via calor seco pelo método da tindalização. O delineamento experimental utilizado foi inteiramente casualizado (DIC), com quatro tratamentos em oito repetições. Os tratamentos consistiram na submissão de um lote de sementes salvas de arroz sob 45ºC em períodos de exposição de 0 (testemunha), 6, 8 e 10 dias, e 1 dia em temperatura ambiente (20oC). As variáveis avaliadas foram: germinação e vigor (índice de velocidade, tempo médio e velocidade média de germinação, comprimento e massa parcialmente seca do sistema radicular e parte aérea de plântulas e envelhecimento acelerado) e patologia de sementes. A aplicação dos tratamentos pré-germinativos não afetou negativamente a germinação. A aplicação da termoterapia pelo período de oito dias resultou na maior germinabilidade das sementes submetidas ao envelhecimento acelerado. Maiores períodos de exposição a temperatura de 45ºC, resultaram em um menor índice de velocidade, menor velocidade média e maior tempo médio de germinação, em relação a testemunha. Na massa parcialmente seca e comprimento das raízes, os maiores períodos de exposição reduziram as variáveis, enquanto na parte aérea ocorreu o aumento, em relação à testemunha. No teste de envelhecimento acelerado quanto maior o período de exposição a 45ºC, maior a germinação das sementes. A alta qualidade fisiológica das sementes amenizou os possíveis danos ocasionados pela termoterapia. Conclui-se que o tratamento térmico nas sementes de arroz quando submetidas sob temperaturas controladas resulta em índices superiores no desempenho germinativo das sementes.

O feijão-comum (Phaseolus vulgaris L.), representa um componente fundamental na alimentação global, desempenhando um papel de destaque como fonte significativa de proteínas e fibras. Contudo, a produção de feijão-comum está suscetível a incidência de diversas doenças que podem comprometer o rendimento da cultura, entre as quais destaca-se a antracnose, cuja etiologia está associada à infecção provocada pelo patógeno Colletotrichum lindemuthianum. Diante disso, o trabalho teve como objetivo avaliar a reação de diferentes cultivares de feijão-comum (Veloz, Tuiuiu, Uiapuru, Urutau e Esteio) à antracnose através do método da folha destacada. Os dados de índice de severidade foram integralizados pela área abaixo da curva de progresso da severidade (AACPS), os valores obtidos foram submetidos à análise de variância e a comparação das médias foi realizada pelo Teste de Tukey ao nível de 5% de probabilidade. A maior severidade da doença foi observada nas cultivares Uiapuru, Urutau e Veloz. Por outro lado, nas cultivares Tuiuiu e Esteio os sintomas foram reduzidos.