Morphological and pathological variations in rapeseed and mustard isolates of Sclerotinia sclerotiorum from Rajasthan

摘要

The studies were conducted to compare the morphological and pathological variations among 38 isolates of Sclerotinia sclerotiorum, derived from single lesion / sclerotium oon rapeseed and mustard, collected from different locations of 14 districts of Rajasthan. All the isolates showed variation in their morphological traits ie., colony colour and shape, and sclerotial number, size,position and pattern when grown on PDA. According similarities, they put in a group and thus 9 groups (G1 to G9) of 38 isolates were established. Pathogenic variability of these isolates (representative of each group) was evaluated by inoculation at 30 days after sowing on 10 different rapeseed and mustard genotypes in potted conditions. Subsequently, disease incidence was recorded up to the survival of the crop. All the groups were virulent on all the 10 genotypes tested for virulence, except G2 on GM-1 and G9 on RN-393, Rohini and SEJ-2. Among these groups, G6 was the most virulent causing maximum disease incidence (82.44%)followed by G1 (77.50%) and G8 (75.01%) while G9 had minimum average disease incidence (11.08%).