Variation in cultural characteristics, mycelial compatibility and pathogenic potentiality among the isolates of Sclerotinia sclerotiorum (Lib.) De Bary the causal agents of stem rot of mustard ( Brassica spp.)

摘要

Variability among 15 isolates of Sclerotinia sclerotiorum (Lib.) de Bary isolated from stem rot of mustard (Brassica spp.) collected from five mustard growing areas of Bangladesh was studied. The isolates varied in colony morphology, mycelial growth rate and number of sclerotia formation. Variation of mycelial compatibility among the isolates was also observed and recorded. Different isolates of same district showed compatible reactions and the sclerotia produced in a regular circle of culture plate. But different isolates of different districts showed incompatible reaction line, even sclerotia formation and showed difference in zone circle. The pathogenic aggressiveness of different isolates were also studied and found isolates of Joypurhat (Joy1, Joy2 and Joy3) were virulent, produced symptom (27.69 - 29.69 mm) in extent on leaves of a susceptible variety Brassica rapa (BARI shorisha-14) within 72 hrs of inoculation. The isolates obtained from different districts showed variability in their pathogenic potentiality and produced symptom within 3 - 4 days of inoculation. Isolates of S. sclerotiorum obtained from samples of Habiganj district (H1, H2 and H3) were less pathogenic compared to other isolates of the fungus and produced symptom after 7 days of inoculation which was very small (10.67 - 12.33 mm).