Comportamento in Vitro Do Agente Etiológico Da Fusariose E Avaliação De Métodos De Inoculação Em Abacaxizeiro

Abstract

RESUMO -O presente estudo objetivou avaliar o comportamento in vitro do fungo Fusarium guttiforme em condições de temperatura e luminosidade distintas e determinar o método de inoculação mais eficiente para a avaliação da resistência de abacaxizeiro à fusariose. Para a determinação do comportamento in vitro foram realizados dois experimentos utilizando para cada o delineamento inteiramente casualizado, em esquema fatorial 3x3 (três temperaturas e três regimes de luminosidade), com cinco repetições para avaliação do índice de crescimento micelial e produção de conídios. As avaliações dos métodos de inoculação foram realizadas em delineamento inteiramente casualizado, com arranjo fatorial 3x4 (métodos x distância de inoculação) a partir de folhas "D" de abacaxizeiro da cv. Pérola, inoculadas a 2, 5, 8 e 11 centímetros da base pelos métodos palito infestado com estruturas do patógeno, disco de micélio sem ferimento e disco de micélio com ferimento na folha. Não houve diferença significativa no comportamento in vitro dos isolados analisados. A temperatura e fotoperí-odo recomendadas para a multiplicação de F. guttiforme foram de 25°C e 12 horas, respectivamente, por apresentar maior índice de crescimento micelial e produção conídios. O método indicado para avaliação de resistên-cia à fusariose do abacaxizeiro por meio de inoculação foi o palito infestado com estruturas do patógeno, a uma distância de 2 a 11 cm da base da folha. Para que ocorra infecção do patógeno F. guttiforme faz-se necessário a realização de ferimento no local a ser inoculado.Palavras-chave: Fusarium guttiforme. Ananas comosus var. Comosus. Resistência. BEHAVIOR IN VITRO OF THE FUSARIUM GUTTIFORM AND EVALUATION OF THE INOCULATION METHODS IN THE LEAVES OF PINEAPPLEABSTRACT -This study aimed to evaluate the in vitro behavior of the fungus Fusarium guttiform in different conditions of temperature and luminosity and determine the most efficient inoculation method for evaluating the resistance of pineapple to fusariosis. To determine the in vitro behavior, two experiments was performed, with the same design, conduction, and evaluation. It was used a completely randomized experimental design in a factorial arrangement of 3x3 (three temperatures and three light regimes), with five replications. The evaluations of inoculation methods were conducted in a completely randomized design with factorial arrangement 3x4 (methods x distance of inoculation). D leaves of pineapple, cultivar Pearl, were inoculated at two, five, eight and eleven centimeters from the base by the methods of infected toothpick, mycelium disc without injury and mycelium disc with injury on the leaf. There was no significant difference on in vitro behavior of the isolates analyzed. The indicated temperature and luminosity for the multiplication of F. guttiform were 25°C and 12 hours, respectively, since they showed significant my celial growth and increased production of reproductive structures. The indicated method for evaluation of resistance to fusariosis in pineapple was the inoculati...

METHODS FOR INOCULATION WITH Fusarium guttiforme AND GENETIC RESISTANCE OF PINEAPPLE (Ananas comosus var. comosus)

“…, with a 12-hour photoperiod, and in test tubes with sand, stored in a refrigerator at 4°C±2°C (GARCIA et al, 2015). …”

“…The Petri dishes with toothpicks were maintained in a BOD incubator at 25°C, with a 12-hour photoperiod for 10 days. The pathogen was inoculated by the toothpick inoculation method, inserting toothpicks with pathogen structures in the leaves (B, D and F) at five centimeters from the leaf base (SANTOS; MATOS; CABRAL, 2001a;GARCIA et al, 2015). Non-infected toothpicks were dipped in sterile distilled water and used as negative control.…”

“…Some inoculation methods in incubation conditions have already been successfully used to identify genetic resistance sources in pineapple (OLIVEIRA; LEITE; PEREIRA, 2011). Giacomelli, Roessing and Teófilo Sobrinho (1969) conducted the first studies regarding pineapple resistance to fusariosis, assessing the pathogen incidence in fruits. Although efficient, this method is slow, since the crop cycle lasts on average 18 months.…”