Exploration of Resistance Level Against Black Scurf Caused by Rhizoctonia Solani in Different Cultivars of Potato

Black Scurf is one of the destructive fungal diseases of potato crops caused by fungus Rhizoctonia solani. Cultural practices and fungicide applications are insufficient in effectively combating the pathogen, while utilizing resistant cultivars has become one of the most economical and effective way to control disease. About ten commercial potato varieties were screened out against the disease by artificially inoculating the plants with R. solani and these potato varieties were grouped based on disease incidence and disease severity. Four varieties (Ronoldo, Rubi, Challenge, and Sadaf) were grouped as resistant, three varieties (SH-5, Sante and Astrex) as moderately susceptible and three varieties (Karoda, Mosica and Simply red) as susceptible with significantly highest disease incidence (P ≤ 0.05). Disease also reduced number and size of tubers, while the disease incidence showed negative (P < 0.001) correlation with chlorophyll and protein contents, and activities of catalase (CAT), peroxidase (POX) and polyphenol oxidase (PPO) enzymes. It was concluded that a combination of phenotypic and physiological indices could be used to identify black scurf resistance in potatoes.