Abstract
Bell Pepper, Capsicum annuum is one of the most important vegetable products with valuable food ingredients which is used almost anywhere in the world. One of the most important diseases of root and crown rot of pepper is Phytophthora capsici in Iran and around the world. Resistant sources play a major role in disease management. Therefore, in this study, the susceptibility of bell pepper genotypes to root and crown rot, Ph. capsici were assessed. The experiments were carried out under laboratory and greenhouse conditions in a completely randomized design with 14 genotypes including Ganga, Lirika, Arunica, Helsinki, Hora, Zamboni, Bachata, Paleo, Phogo, Siroosi, Horen, PS, Hot Chili and Syrna in 15 replications. All the pepper genotypes were imported from RIJK ZWAAN Co., and was provided by Sepahan Royesh Company in Isfahan. The inoculum was prepared in the petri dishes with agar containing 10 days old pure culture of Ph. inoculated at seedlings stage in the pots containing sterile soil by 2-3 pieces of 5 mm in diameters around the crown of each plant. This method of inoculation was repeated in three stages of plant growth, seedling, flowering and maturity. Following inoculation, a total of 8 stages of the plants were evaluated a weekly, and the status of damping off per replicate and for each variety of bell pepper were counted separately. Variance on mortality rate of pepper plants at different stages of development for varieties was analyzed by SAS software separately and in combined at 1% probability level, and the means with using Duncan's multiple range test, DMRT and T test, and cluster analysis was performed by drawing a dendrogram and genotyping by software (SPSS, SAS). The results indicating that the cultivars showed a significantly different reaction to the Ph. capsici pathogenicity tests and were divided into five distinct groups. Finally, the Helsinki cultivar with Horne cultivar with 15 plant infections were the most susceptible one followed by Lirika with 14.5, Arunica 14.33, Syrena 14.33, Zombine 14.14 and PS with 14.16 infected plants in the next category. Hora cultivar with an infection rate of 7.16 plants followed by Paleo with 10.5 infected plants showing the least infected cultivars, respectively. Other cultivars with significant effect were included in the related statistical groups.