Comportamento in vitro de Chalara paradoxa sob diferentes condições de cultivo

Abstract

The black rot of pineapple fruits (Ananas comosus L.), caused by the Chalara paradoxa, is considered the main post harvest disease of this crop, causing high losses in fruit for the fresh market and industry. Studies are scarce regarding the knowledge and nutritional morphophysiological best conditions of this pathogen involving different culture conditions, such as culture media, temperatures and luminosities, which are key factors in determining the behavior of the pathogen. Therefore, the objective of this work was to evaluate the in vitro behavior of C. paradoxa in different growing conditions, mycelial growth, sporulation and germination while information that can support the management of the pathogen under field conditions. The culture media used was (potato - dextrose agar, oat dextrose agar, dextrose agar pineapple and coconut milk dextrose agar), at 15, 25 and 35 ° C and different luminosities (continuous light, continuous dark and alternating light) in BOD. Mycelial growth was assessed daily by measuring in two diametrically opposite directions for five days, during which fungal growth has completed entire length of the Petri dish. It was evaluated the rate of germination and sporulation of conidia suspension by the addition of 2 mL of distilled water in plates containing the fungal colonies, and observed in hemacytometer. The experimental design was completely randomized with five replications in a factorial design (4 x 3 x 3). Data were subjected to analysis of variance and means were compared by Tukey test at 5% probability. The results showed that the best conditions for in vitro cultivation of C. paradoxa for mycelial growth, sporulation and germination were obtained at 25 °C, for OAT and PDA in alternating light and PDA with continuous dark regime.