Evaluation in greenhouse of the response of two Musa cultivar to Black Sigatoka by artificial inoculation of conidial suspension of Pseudocercospora fijiensis

Abstract

For evaluating the resistance of Black sigatoka in genotypes from breeding programmes different methods have been used, the artificial inoculation of pathogens reproduction structures is one of them. Nevertheless, is necessary the standardization of condition for it in vitro production and to know the response of cultivars to the diseases in greenhouse. It will permit to establish methods for evaluating and selecting the new resistant genotypes. This work was carried out with the objectives to evaluate different culture media and incubation conditions for obtaining P. fijiensis conidia and for evaluating the response of two cultivars to the artificial inoculation with conidial suspensions of this fungus. Different culture media and incubation conditions for obtaining the conidia and the cultivars Grande naine (susceptible) and FHIA-18 (partially resistant) were used. The conidia of P. fijiensis could be obtained in vitro at 20ºC and constant light from 10 days of incubation in culture media Potato Carrot Agar, modified V-8 Agar and Potato Dextrose Agar. However, the greatest concentration was reached in Potato Dextrose Agar after 20 days of incubation at 20ºC under continuous white fluorescent light. The artificial inoculation of conidial suspensions of P. fijiensis allowed to evaluate the response of Grande Naine and FHIA-18 cultivars in greenhouse. By the use of qualitative scale of symptoms stages and the quantitative variables symptoms evolution time and disease development time was possible to differentiate both cultivars. They maintained in greenhouse similar response to the disease that in the field. Key words: conidia, culture medium, FHIA-18, Grande naine, sporulation