O presente trabalho teve como objetivo avaliar o potencial de produtos à base de fosfitos de potássio, cobre e manganês, na ativação da Resistência Sistêmica Adquirida (RSA) em plantas de soja. O delineamento foi inteiramente casualizado, com 5 tratamentos constituídos de fosfito de potássio 0,002%, fosfito de manganês 0,002%, fosfito de cobre 0,002%, Acibenzolar-S-Metil (0,005%) e a testemunha (água destilada), em quatro repetições. O experimento foi realizado na Universidade Tecnológica Federal do Paraná (UTFPR), Campus Dois Vizinhos, em casa de vegetação. A cultivar de soja foi a Nidera 5909, semeada em vasos com capacidade de 10 litros, e as plantas conduzidas até o estádio fenológico R1 (Início do florescimento) momento onde ocorreu os tratamentos. Antes da aplicação dos tratamentos (tempo inicial) e após a aplicação dos tratamentos, em intervalos de 24, 48, 96 e 192 horas, foram realizadas coletas de materiais vegetais para as análises bioquímicas, onde quantificou-se a atividade de enzimas relacionadas à ativação da RSA, sendo a fenilalanina amônia-liase, quitinase e ?-1,3 glucanase. A inoculação dos esporos da ferrugem asiática foi realizada em 48 horas após a aplicação dos tratamentos. Os resultados demonstraram que os fosfitos a base de potássio, cobre, manganês e o ASM, possuem capacidade de ativar enzimas relacionadas à patogenicidade, demonstrando a ativação da Resistência Sistêmica Adquirida em plantas de soja. Tais ativações apresentam especificidade de ação, bem como atuam em mecanismos distintos de defesa.
Ganoderma lucidum is a medicinal mushroom widely used in Eastern countries and currently in global scale. Its fruiting body and mycelium are composed by polysaccharides, triterpenes and more than 200 secondary metabolites. These compounds exhibit a range of bioactivities, such as anti-inflammatory, antitumorigenic, antibacterial and antifungal action. Several scientific publications have demonstrated the potential and performance of G. lucidum compounds in the control of diseases in animals and humans. However, there is a lack of information on the effect of their compounds on the phytopathogens control, whether directly or by activating plant defense mechanisms. In the search of new molecules that has induced activity and disease control, this study was aimed to evaluate the bioactive compounds produced by G. lucidum through liquid culture under elicitation to control powdery mildew (Erysiphe diffusa) in soybean plants. The compounds tested were: C01-distilled water, C02-copper oxychloride (1 L ha-1), FC01-filtered mycelial growth of G. lucidum without elicitation, FC02-G. lucidum filtration of lignin elicitation and FC03-G. lucidum filtration from SA elicitation. The upper part of the plant was sprayed at 20 % (v/v) concentration and 10 mL per plant were applied. All data were analyzed using R® software. The Ganoderma filtrates have shown the induction of resistance potential in soybean plants by the activation of phytoalexins, activation of the enzyme phenylalanine ammonia-lyase, increase of phenolic compounds, peroxidases and chitinase activity, such induction has specificity in relation to time activation and association with elicitors. New studies should be considered, seeking to identify and isolate the active principles present in the filtrates, as well as to evaluate the action of these substances in other pathosystems of agricultural interest.
In recent years, it has been observed a significant expansion of the organic market. In this context, the main phytosanitary problem of soybean in the organic system is Asian rust (Phakopsora pachyrhizi), for which it is difficult to control, considering the restriction of products authorized for use in the organic system and the limitation of research related to this management system. The objective of this study was to evaluate the effect of alternative products on the germination of uredospores, on the severity of soybean rust on detached leaves and the control of the disease under greenhouse and field conditions. The alternative treatments were calcium silicate, lime sulphur, bordeaux mixture, and copper oxychloride. The variables analyzed were uredospores germination, disease severity, defoliation level, area under the disease progress curve (AUDPC), a thousand grain mass and productivity. The results obtained indicate that there is a possibility of using copper oxychloride to manage the Asian rust in organic production systems. Copper oxychloride had reduced the germination of uredospores and when evaluated under controlled conditions using detached leaves and greenhouse, it had reduced the severity of the disease. In field conditions, copper oxychloride at the doses of 588 and 882 g ha-1 reduced severity and AUDPC, in addition to increasing productivity at 1434 kg ha-1 in relation to the control. It is concluded that copper oxychloride can be used as a tool in the management of Asian rust in organic systems of soy production.
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