Citronella essential oil in the control and activation of coffee plants defense response against rust and brown eye spot.

Ano: 2012 | Volume: 36 | Número: 4

Autores: Ricardo Borges Pereira, Gilvaine Ciavareli Lucas, Fabiano José Perina, Pedro Martins Ribeiro Júnior, Eduardo Alves

Palavras-chave: Hemileia vastatrix, Cercospora coffeicola, Cymbopogon nardus, induced resistance, alternative control of plant disease.

Resumo Português:

A ferrugem e a cercosporiose são as principais doenças de cafeeiro. Os prejuízos se devem a intensa desfolha das plantas que têm
sua produção e longevidade reduzidas. A cercosporiose também ocorre nos frutos, com reflexos negativos na qualidade da bebida. Alguns
óleos essenciais têm apresentado resultados promissores no controle de doenças em plantas, em alternativa ao uso de fungicidas. Neste
trabalho, objetivou-se avaliar o óleo essencial de citronela no controle da ferrugem e cercosporiose e na ativação de respostas de defesa
em cafeeiro. Plantas com 12 meses foram pulverizadas com o óleo de citronela 1.000 μL L-1, acibenzolar-S-metil 200 mg L-1 e fungicida
tebuconazole 200 mg L-1 e inoculadas com Hemileia vastatrix e Cercospora coffeicola sete dias após. Repetiu-se a aplicação após 30 dias.
Plantas com cinco meses foram pulverizadas com os mesmos tratamentos para avaliar as respostas de defesa induzidas. O óleo de
citronela controlou a ferrugem e a cercosporiose com eficácias de 47.2% e 29,7%, respectivamente, enquanto tebuconazole apresentou
controles de 96,5% e 90,5%, respectivamente. Acibenzolar-S-metil reduziram em 55,9% a cercosporiose da ferrugem e não apresentou
controle significativo da ferrugem. O óleo de citronela aumentou as atividades de peroxidase e quitinase em mudas de cafeeiro 336 e; 24
e 336 horas após pulverização, respectivamente. Acibenzolar-S-metil aumentou as atividades de peroxidase, quitinase e β -1,3-glucanase
192, 288 e 336 e; 24 e; 240 horas após pulverização, respectivamente. Os tratamentos não promoveram aumento de fenóis, mas aumento
significativo no teor de lignina foi observado em plantas pulverizadas com óleo de citronela.

Resumo Inglês:

The rust and brown eye spot are the main coffee diseases. The losses are due to intense defoliation of plants, which has
reduced its production and longevity. The brown eye spot also occurs in fruits, with negative effects on the beverage quality. Some
essential oils have presented promising results in the control of plant diseases, as an alternative to the use of fungicides. The objective
of this study was to evaluate citronella essential oil in the control of rust and brown eye spot and in the activation of coffee plants
defense responses. Twelve-month-old plants were sprayed with citronella oil 1000 μL L-1, acibenzolar-S-methyl 200 mg L-1 and
tebuconazole fungicide 200 mg L-1. Plants were inoculated with Hemileia vastatrix and Cercospora coffeicola seven days later. The
application was repeated after 30 days. Plants with five months were sprayed with the same treatments to assess the induced defense
responses. Citronella oil controlled rust and brown eye spot with efficiencies of 47.2% and 29.7%, respectively, while tebuconazole
presented control of 96.5% and 90.5%, respectively. Acibenzolar-S-methyl reduced brown eye spot by 55.9% and showed no
significant control of rust. Citronella oil increased peroxidase and chitinase activities in five months coffee plants 336, and 24 and 336
hours after spraying, respectively. Acibenzolar-S-methyl increased peroxidase, chitinase and β -1,3-glucanase activities 192, 288 and
336; 24 and; 240 hours after spraying, respectively. The treatments did not increase accumulation of phenols, but a significant
increase in lignin was observed in plants sprayed with citronella oil.