Investigations on the morphocultural variability and virulence behaviour of Rhizoctonia solani infecting rice in Bihar, India

This study investigates the morphocultural variability and virulence behaviour of R. solani isolates infecting rice in Bihar. Variability in sclerotial characteristics was also recorded. The colony colour ranged from creamy white to yellowish brown, and the growth type ranged from profuse to sparse. Eight of the isolates exhibited faster growth and covered 90 mm in 48 h. The isolates produced sclerotia in 3 to 4 days in different sizes ranging from 1.10 to 2.70 mm in diameter. Diverse results were observed in relation to the number of sclerotia/plates among the isolates, ranging from 19 to 101.7 per plate. Significant variation in virulence was observed within the study isolates with relevance to relative lesion height and disease severity. The isolate RSBR22 was most virulent, with the highest relative lesion height of 73.6 and disease rating scale of 9 in the cultivar Rajendra Sweta.