Morphological and Pathogenic Variability in Alternaria solani Causing Early Blight Disease in Tomato (Lycopersicon esculentum Mill.) in Chhattisgarh, India

The variability is a well-known phenomenon in genus Alternaria solani and may be noticed as changes in etiology, growth and sporulation and pathogenicity. Therefore, present investigation was carried out on ‘morphological and pathogenic variability of Alternaria solani causing early blight in Tomato (Lycopersicon esculentum Mill.) in Chhattisgarh (India)’. Seven isolates of Alternaria solani were collected from different district of Chhattisgarh and studied on morphological and pathogenic variations among the isolates of Alternaria solani. Longest conidia with beak (39.17–74.35µm) were observed in isolate AS-6, while smallest conidia (28.12–58.35µm) were recorded in isolate AS-3. However, width of conidia was maximum (8.82–24.23µm) in isolate AS-3 and thin conidia (8.13 – 19.48µm width) in isolate AS-7. Maximum beak length (7.64–14.78µm) was observed in isolate AS-4 and minimum beak length was recorded in isolate AS-3 (4.18–7.62µm). Highest vertical septa 2–11 was recorded in isolate AS-7 followed by AS-2. Whereas, maximum horizontal septa were recorded in isolate AS-6 followed by isolate AS-3 and AS-4. Pathogenic variability test was performed to analyze the virulence of different isolates of Alternaria solani on Pusa Ruby variety of tomato under pot culture. Most virulent isolate was found AS-6 which exhibited maximum PDI (88.89%) and AUDPC (2302.22) followed by AS-5 and AS-7, while AS-1 was found least virulent which showed minimum PDI (40.00%) and AUDPC (995.56).