Physiological variability of Macrophomina phaseolina (Tassi) Goid. Isolates causing root rot of castor

Abstract

The fungus Macrophomina phaseolina is the devastating fungus of many crops. For this study, infected maize samples were collected from castor growing areas of Gujarat. Twenty-five isolates of M. phaseolina were isolated from infected castor samples and their growth was evaluated at 20, 25, 30, 35 and 40°C as well as at 5.0, 5.5, 6.0, 6.5, 7.0, 7.5 and 8.0 pH. The growth of fungal isolates was significantly affected by different levels of temperature and pH. Among different five temperature levels, significantly maximum mean growth (89.53 mm) was observed at 35 ºС temperature followed by 30 ºС(82.46 mm) after four days of incubation on PDA medium. Among different seven pH levels, significantly maximum mean growth of dry mycelial (352.42 mg) was recorded at pH 7.0 followed by pH 6.5 (313.70 mg) and pH 6.0 (311.02 mg), however pH 6.5 and pH 6.0 were statistically at par with each other. Among different seven pH levels, significantly maximum mean growth of dry mycelial (352.42 mg) was recorded at pH 7.0 followed by pH 6.5 (313.70 mg) and pH 6.0 (311.02 mg), clearly indicated the preference of isolates to particular range of pH. Mean dry mycelial weight was increased with increase in pH and temperature.