بررسی حساسیت ارقام و لاین های سیب زمینی به بیماری شانکر رایزوکتونیای ساقه

Canker and black scurf disease of potato with Rhizoctonia solani fungal agent is one of the most important potato diseases Most of the cultivation areas of this product are that which greatly reduces the amount of the product. This fungus has a wide host range. To access sources of resistance, research was done on potato cultivars and lines to stem canker disease in the Faridan region (Isfahan). The studied cultivars and lines were prepared from the reserves of the Isfahan Seedling and Seed Research Department. 48 genotypes in this study were investigated in fields with a history of high contamination in the Faridan region )Isfahan) and as a completely randomized block design and in 3 replications. The characteristics studied included a percentage of contamination and severity and index of the disease. To determine the amount of contamination with the disease Rhizoctonia stem canker, 10 plants were randomly sampled from each repetition. To determine the severity of the disease, Based on the descriptive model of the British National Institute of Botany known as (NIAB) and the samples in 6 scales Zero, 10, 25, 50, 75, and 100% pollution were categorized. The number of infected plants in each spectrum was multiplied by the corresponding numbers and Their sum was obtained and then divided by the total number of plants sampled and the average contamination in each replicate was calculated. Statistical analysis with Duncan's multi-domain test and SPSS software were used. The study showed that based on the analysis tables Variance and Duncan's test, there was a high level of pollution in the area, and the investigated lines showed different levels of pollution to each other.The results of the analysis of variance in field conditions in Isfahan for the intensity of infection with Rhizoctonia fungus showed that there is a significant difference at the level of 1% between the genotypes. The results show that line 8707/137 with 55.5% contamination, 4/33/R1 line with 47%, and 21/33/R2 line with 46.83% have the highest average contamination percentage so they are evaluated as the most sensitive genotype in the Isfahan region. Also, the 8708/87 line with 24.5%, Line 8708/2 with 23.6%, and Line 31/33/R2 with 21.7% showed the lowest level of contamination and therefore the most resistant genotypes were identified. Also, genotypes 8707/29, 8707/26 and 28/33/R3 are tolerant genotypes. Other genotypes are relatively "resistant" and relatively "sensitive". Cluster analysis grouped cultivars and lines into 5 categories differently, which were closely similar to the results of Duncan's test. Most of the rhizoctonian isolates from these regions were confirmed as AG3.