Níquel no controle do oídio (Erysiphe diffusa) e ferrugem asiática (Phakopsora pachyrhizi) na cultura da soja
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Data
2016-07-14
Autores
Barcelos, Jéssica Pigatto de Queiroz [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O níquel (Ni) é um micronutriente para as plantas por ser componente estrutural da urease, enzima que catalisa a degradação da ureia em dióxido de carbono e amônia, além disso, tanto Ni quanto a urease desempenham importante papel no metabolismo antioxidante da planta e no controle de doenças fungicas. Assim, objetivou-se com este trabalho avaliar o efeito da aplicação foliar de doses de Ni associado ou não à fungicidas do grupo das estrobilurinas em plantas de soja sobre o controle de doenças fungicas, a atividade de enzimas antioxidantes, a produtividade e sobre a qualidade de sementes. Foram realizados três experimentos sendo o primeiro na Chapadão do Sul – MS utilizando a molécula Piraclostrobina (75 g i.a. ha-1), o segundo em Selviria – MS utilizando as moléculas Fluxapiroxade + Piraclostrobina (300 mL p.c. ha-1), e o terceiro experimento foi realizando em Londrina – PR utilizando as moléculas Picoxistrobina + Ciproconazole (300 mL p.c. ha-1). Os três experimentos foram realizados em delineamento de blocos ao acaso, em esquema fatorial 7 x 2, sendo sete doses de Ni (0; 10; 20; 40; 60; 80 e 100 g ha-1) associadas ou não aos fungicidas, e quatro repetições totalizando 56 parcelas, os tratamentos foram aplicados no estágio fenológico R1 em todos os experimentos, e apenas no experimento III foi realizada uma segunda aplicação em R4. Junto do experimento III também foi realizado um experimento em placas de petri para avaliar o efeito do Ni sobre a germinação de urediniósporos de Phakopsora phachyrhizi com os seguintes tratamentos Picoxistrobina + Ciproconazole 100 mL L-1 como controle; (0; 0,1; 0,2; 0,3; 0,5; 0,8; 1,0; 2,0; 2,5; 3,0; 3,5; 5,0 g L-1 de Ni) com seis repetições. No experimento I houve aumento nos teores de nitrogênio e de índice SPAD, e nas menores doses de Ni houve aumento de produtividade. Em relação a qualidade fisiológica de sementes, a porcentagem de germinação e a taxa de emergência aumentaram linearmente com o aumento das doses de Ni sem fungicida. Porém, quando o Ni foi associado a piraclostrobina a porcentagem de germinação apresentou ajuste quadrático, com aumento da germinação até a dose de 40 g ha-1 de Ni. No experimento II houve a ocorrência natural de oídio (Erysiphe diffusa), e a aplicação de 60 g ha-1 de Ni associado a 300 mL p.c. ha-1 do fungicida reduziu a severidade do oídio a 99%, foram observadas atividades máximas das enzimas urease, superóxido dismutase (SOD), catalase (CAT) e peroxidase (POD). No experimento III no ensaio de placas, a aplicação de Ni controlou a germinação de urediniósporos de P. pachyrhizi, no campo entretanto o Ni não foi eficiente no controle da ferrugem asiática, e não houve diferença significativa para produtividade. A combinação de doses de Ni e fungicida aumentou a concentração de peróxido de hidrogênio e peroxidação lipídica, indicando a formação de espécies reativas de oxigênio no tecido foliar. Em todos os experimentos houve aumentou os teores de Ni nas folhas e nos grãos Houve efeito sinérgico dos fungicidas sobre a atividade da urease nas menores doses.
Nickel (Ni) is a micronutrient for the plants to be structural component of urease, an enzyme that catalyzes the degradation of urea to ammonia and carbon dioxide, in addition, both Ni and urease plays an important role in antioxidant metabolism of the plant and control of fungal diseases. Thus, the aim of this study was to evaluate the effect of foliar application of Ni doses with or without group of fungicides of the strobilurin in soybean plants under the control of fungal diseases, the activity of antioxidant enzymes, productivity and the quality seeds. Three experiments were conducted being the first in Chapadãodo Sul - MS using Pyraclostrobin molecule (75g a.i. ha-1), the second Selvíria - MS using the Fluxapyroxad + Pyraclostrobin molecules (300ml c.p. ha-1) and the third experiment was performing in Londrina - PR using the Picoxystrobin + Cyproconazole molecules (300ml pc ha-1). The three experiments were performed in design of randomized blocks in a factorial 7 x 2, seven Ni doses (0; 10; 20; 40; 60; 80 e 100 g ha-1) associated or not to fungicides, and four replications totaling 56 plots, the treatments were applied at the phenological stage R1 in all experiments, and only in the experiment III was carried out a second application in R4. Along III experiment was also performed an experiment in petri plates to evaluate the effect of Ni on the germination of Phakopsora uredospores phachyrhizi with the following Picoxystrobin Cyproconazole + 100 mL L-1 treatment as a control; (0; 0.1; 0.2; 0.3; 0.5; 0.8; 1.0; 2.0; 2.5; 3.0; 3.5; 5.0 g L-1 Ni) with six replications. In the first experiment there was an increase in nitrogen content and SPAD index, and the smaller Ni doses there was an increase in productivity. Regarding the physiological quality of seeds, germination and emergence rate increased linearly with increasing Ni doses without fungicide. However, when Ni was associated with pyraclostrobin the germination percentage showed a quadratic fit with increased germination to the dose of 40 g ha-1 Ni. In the second experiment there was the naturally occurring powdery mildew (Erysiphe diffusa), and the application of Ni 60 g ha-1 associated with 300ml c.p. ha-1 fungicide reduced the severity of powdery mildew than 99%, maximum activity of the enzymes urease, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were observed. In the third experiment in the ‘in vitro’ test, the application of Ni controlled urediniospores of Phakopsora pachyrhizi germination, however in the field Ni was not effective in controlling asian soybean rust, and there was no significant difference in productivity. The combination of Ni and fungicide doses increased the concentration of hydrogen peroxide and lipid peroxidation, indicating the formation of reactive oxygen species in the leaf tissue. In all experiments was increased Ni content in the leaves and grains.There was synergistic effect of fungicides on the urease activity in smaller doses.
Nickel (Ni) is a micronutrient for the plants to be structural component of urease, an enzyme that catalyzes the degradation of urea to ammonia and carbon dioxide, in addition, both Ni and urease plays an important role in antioxidant metabolism of the plant and control of fungal diseases. Thus, the aim of this study was to evaluate the effect of foliar application of Ni doses with or without group of fungicides of the strobilurin in soybean plants under the control of fungal diseases, the activity of antioxidant enzymes, productivity and the quality seeds. Three experiments were conducted being the first in Chapadãodo Sul - MS using Pyraclostrobin molecule (75g a.i. ha-1), the second Selvíria - MS using the Fluxapyroxad + Pyraclostrobin molecules (300ml c.p. ha-1) and the third experiment was performing in Londrina - PR using the Picoxystrobin + Cyproconazole molecules (300ml pc ha-1). The three experiments were performed in design of randomized blocks in a factorial 7 x 2, seven Ni doses (0; 10; 20; 40; 60; 80 e 100 g ha-1) associated or not to fungicides, and four replications totaling 56 plots, the treatments were applied at the phenological stage R1 in all experiments, and only in the experiment III was carried out a second application in R4. Along III experiment was also performed an experiment in petri plates to evaluate the effect of Ni on the germination of Phakopsora uredospores phachyrhizi with the following Picoxystrobin Cyproconazole + 100 mL L-1 treatment as a control; (0; 0.1; 0.2; 0.3; 0.5; 0.8; 1.0; 2.0; 2.5; 3.0; 3.5; 5.0 g L-1 Ni) with six replications. In the first experiment there was an increase in nitrogen content and SPAD index, and the smaller Ni doses there was an increase in productivity. Regarding the physiological quality of seeds, germination and emergence rate increased linearly with increasing Ni doses without fungicide. However, when Ni was associated with pyraclostrobin the germination percentage showed a quadratic fit with increased germination to the dose of 40 g ha-1 Ni. In the second experiment there was the naturally occurring powdery mildew (Erysiphe diffusa), and the application of Ni 60 g ha-1 associated with 300ml c.p. ha-1 fungicide reduced the severity of powdery mildew than 99%, maximum activity of the enzymes urease, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were observed. In the third experiment in the ‘in vitro’ test, the application of Ni controlled urediniospores of Phakopsora pachyrhizi germination, however in the field Ni was not effective in controlling asian soybean rust, and there was no significant difference in productivity. The combination of Ni and fungicide doses increased the concentration of hydrogen peroxide and lipid peroxidation, indicating the formation of reactive oxygen species in the leaf tissue. In all experiments was increased Ni content in the leaves and grains.There was synergistic effect of fungicides on the urease activity in smaller doses.
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Palavras-chave
Ureia, Controle de doenças, Glycine max, Enzimas antioxidates, Urea, Disease control, Soybean, Antioxidant enzymes