Screening of Onion Varieties Against Purple Blotch and Role of Soil Nutrient Factors Affecting Disease Development

An assessment of 16 onion varieties was conducted to evaluate their resistance to purple blotch disease, primarily caused by various Alternaria species, including Alternaria tenuissima. The findings revealed that none of the varieties exhibited complete resistance to the disease. The varieties were classified into three distinct categories based on their susceptibility levels. Eight varieties had a moderate resistance level, with an infection rate of 11?20% of the leaf area. These varieties, namely Ellora China King, Ellora Wonder 101, Onion Shyamla-111, Bhima Raj, Bhima Super, F1 Kalia, China Nashik Red, and Bhima Light Red, were promising. On the other hand, seven varieties, including Bhima Red, Bhima Shakti, Bhima Kiran, F1 AGNR 102, Bhima Shubhra, Panchaganga, and Bhima Dark Red, were categorized as moderately susceptible, showing infection in the range of 21?40% of the leaf area. Remarkably, Pune Fursungi stood out as the only variety entirely susceptible to the disease, with a significant 41?60% of the leaf area affected.. KEYWORDS :Alternaria tenuissima, Onion, Purple blotch disease, Resistance, Soil nutrients