RIBEIRO JÃNIOR, Pedro Martins. Phosphites for the protection and induction of resistance in coffee plants against Hemileia vastatrix and Cercospora coffeicola. 2008. 105p. Thesis (Doctorate in Phytopathology) â Federal University of Lavras, Lavras. / âFosfitos na proteÃÃo e na induÃÃo de resistÃncia do cafeeiro contra Hemileia vastatrix e Cercospora coffeicolaâ

AUTOR(ES)

Pedro Martins Ribeiro JÃnior

DATA DE PUBLICAÇÃO

2008

RESUMO

The present work was aimed at evaluating the effect of the application of potassium, manganese and zinc phosphites on the control of rust and brown eye spot of coffee plants in the field; to verify the protective effect of these products and of acibenzolar-S-methyl (ASM) against brown eye spot on coffee seedlings and to study the mechanisms involved in the defense response of coffee seedlings against brown eye spot. To fulfill these objectives, three experiments were carried out. The first experiment was carried in a coffee plantation with a four year old Topazio cultivar, assessing rust and brown eye spot during two consecutive years (2006 and 2007). The second and third experiments were carried in a greenhouse with âMundo Novoâ cultivar, inoculating Cercospora coffeicola. The phosphites provided, on average, smaller indices of rust and brown eye spot on coffee plants in the field, if compared to the control, and higher indices of these diseases compared to the fungicide, during two years of evaluation. In greenhouse, phosphites and ASM provided protection of coffee seedlings, therefore lower number of lesions per leaf and lower incidence of brown eye spot were evidenced. Plants sprayed with potassium and manganese phosphites had higher activity of peroxidase, chitinase and β 1,3-glucanase. The highest enzymatic activities were observed mainly at the last evaluations, from 7 up to 21 days, except for β 1,3-glucanase, which had its activity increased in the first hours for treatments with ASM and manganese phosphite. No effect of the treatments on the content of soluble lignin was observed until 21 days after spraying. Treatments with phosphites increased soluble phenolic content compared to ASM and to the control. The effect of phosphites on the control of brown eye spot and rust of coffee plants, is probably due to both, their direct toxic effect associated with their effect on the induction of resistance.

ASSUNTO(S)

glucanase brown eye spot ferrugem glucanases cercosporiose quitinases coffea arabica peroxidase fitopatologia coffea arabica leaf rust peroxidases lignin lignina chitinase

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