Morphological Variability in Alternaria brassicae Isolates of Indian Mustard, Brassica juncea L. Czern. & Coss.

Variation in morphological characteristics among six isolates of Alternaria brassicae, the causal agent of Alternaria blight of rapeseed-mustard, was studied. All the isolates showed high level of variability in vitro in respect of radial growth, conidia length, width, beak length and number of septa. These samples were isolated and purified by single spore technique to studied thse morphological and radial growth behaviour on PDA at 25±1°C. Radial growth varied from 70.70 to 90.00 mm. The average conidial length ranged from 105.75 to 136.73 μm and width from 11.13 to 15.70 μm. The conidial beak length varied from 50.00 to 71.08 μm. Number of transverse and longitudinal septa ranged from 6.00 to 8.00 and 0.25 to 2.75 respectively.