Optimization of Cultural Conditions for Cochliobolus heterostrophus Isolates from Infected Maize Plants from Different Agricultural Zones of Pakistan
Iffat Naz *
Department of Microbiology, Quaid-i-Azam University, Islamabad 45320, Pakistan and National Agricultural Research Centre, Islamabad 45320, Pakistan
Shama Sehar
Department of Microbiology, Quaid-i-Azam University, Islamabad 45320, Pakistan
Irum Perveen
Department of Microbiology, Quaid-i-Azam University, Islamabad 45320, Pakistan
Abdul Rehman
Department of Microbiology, Quaid-i-Azam University, Islamabad 45320, Pakistan
Amber Hameed
Department of Microbiology, Quaid-i-Azam University, Islamabad 45320, Pakistan
Yasmin Ahmad
National Agricultural Research Centre, Islamabad 45320, Pakistan
Safia Ahmed
Department of Microbiology, Quaid-i-Azam University, Islamabad 45320, Pakistan
*Author to whom correspondence should be addressed.
Abstract
Southern corn leaf blight caused by Cochliobolus heterostrophus is a major foliar disease of maize crop in Pakistan. The disease affects leaves, leaf sheaths, ears and maize grains. Suitable physiological conditions which include different nutrient media, temperature, pH, carbon and nitrogen sources were determined for growth and reproduction of the pathogen. Among all media used viz, the best supporting medium was found to be Richard’s agar for the growth of pathogen after 7 days of incubation. Different temperatures (20, 25, 30 and 35ºC) were selected for mycelia growth of the pathogen, among which maximum growth was found to be at 30ºC (80 mm colony size) and minimum at 35ºC (35 mm). Maximum radial colony growth of the pathogen was observed at neutral pH (80 mm). Sucrose and potassium nitrate (KNO3) were found to be the most appropriate sources of carbon and nitrogen respectively.
Keywords: Cochliobolus heterostrophus, southern corn leaf blight, pathogenicity test, maize