Cultural and morphological variability of isolates of Sclerotium rolfsii causing stem and pod rot of groundnut

摘要

Eighty isolates of Sclerotium rolfsii collected from viz., Raichur, Ballari, Koppal, Gadag, Tumkur, Chitradurga, Kalburgi and Yaadgir districts of Karnataka were used to study cultural and morphological variability based on their radial growth, colonymorphology, sclerotial production, pattern of production of sclerotial bodies, number of days taken to produce sclerotial bodies, number of sclerotial bodies produced per plate, colour, size and texture of sclerotial bodies. Significant variability withreference to mycelial and sclerotial characters across isolates of S. rolfsii isolated from different locations of Karnataka was observed. Out of eighty isolates, 73 isolates were fast growing with an average growth rate 75-90 mm, five intermediate growing isolates 60-75 mm and two isolates slow growing with an average growth rate of 45-60 mm. With respect to colony morphology, fifteen isolates showed compact growth while sixty five isolates showed fluffy growth and sixty four isolates produced sclerotial bodies scattered all over the plate, thirteen isolates which produced sclerotial bodies at the periphery region whereas, isolate Sr33 and Sr34 produced sclerotial bodies at the centre of plate. Further, all eighty isolates produced sclerotial bodiesexcept Sr77 which did not produce sclerotial bodies. Most of the isolates produced sclerotial bodies within 11-14 days except Sr60 which took 19 days and the isolate SM5 recorded the production of more than 300 sclerotial bodies per plate.