A set of three experiments were conducted in a completely randomized design with 10 replications/treatment aimed at evaluating inoculation methods, inoculum concentrations and seedling age to establish an effective methodology for evaluating papaya accesses for resistance to P. palmivora. In experiment 1, 60 days-old seedlings of three genotypes (Golden, Kapoho Solo and Calimosa) were inoculated using three methods - deposition of 1 mL of zoospore suspension around seedlings planted on wet (DSW) and dry substrate (DDS), and immersion of the seedling root system in 200 mL of the inoculum suspension for 20 minutes (IRS) - and five inoculum concentrations 5x10³, 10(4), 5x10(4), 10(5) and 5x10(5) zoospores/mL; in experiment two, two genotypes (Golden and Kapoho Solo), two inoculation methods (DSE and DSS) and three inoculum concentrations (10(4), 5x10(4) and 10(5)) were tested. Experiment three was aimed at selecting an adequate seedling age. Three papaya genotypes at ages of 45, 60, 75 and 90 days were inoculated through the DSS method using the inoculum concentration of 5x10(4) zoospores/mL and 25 seedlings/treatment. In all experiments the mean number of days of seedling survival after inoculation (days) was utilized for treatment comparisons using Tukey's statistical test (p>0,05). Results of the experiments have indicated that the DDS method of inoculation, the use of 60 day-old seedlings and application of a suspension of 10(5) or 5x10(4) zoospores/mL are adequate for accessing papaya seedling resistance against P. palmivora.
Carica papaya; Peronosporales; foot-and-fruit-rot; methodology of inoculation
