Tomato evaluating resistance against pathogenic isolates of the fungus Alternaria alternata f.sp. lycopersici disease agent stem canker

In this study the reaction of 27 tomato cultivars available in the country with isolates of Alternaria alternata f.sp. lycopersici collected from different regions were evaluated. For this purpose, to collect isolates from different regions and the pathogenicity of tomato varieties Pete Early-CH (susceptible to stem canker) was used. To identify the pathogen measurements were carried out in both macroscopic and microscopic. In this way, the color of the Colony and other macroscopic properties of the medium were examined under a microscope to examine the treatment of fungal spores and conidiophores and 100 were measured for each isolate was determined as the average. Other specifications, such as number of walls, length, width and color were investigated. A sample collected for testing of isolates susceptible cultivar was selected based on disease severity index. Selected varieties of seedlings after planting and transferred to pots in a greenhouse with suspension isolates of the fungus were inoculated in separate tests to measure disease incidence (Disease severity index) on the stem, after the elapse of the incubation period and the rise . Results of the evaluation showed that three varieties of stem canker Ps 550 and Xamen and Super Set in evaluating the area under the curve progression of the disease in stem cultivars, showed the lowest levels of development and were identified as resistant varieties. In order to study the fungus producing extracellular compounds and their role in the disorder, disease-causing bacteria in the PDB (infantry, dextrose liquid culture medium potatoes) Potato Dextrose Broth were killed. Tomato seedlings and leaflets for susceptibility to extracellular secretions (toxins) were evaluated. .