Influence of culturing conditions on growth and sporulation of Drechslera hawaiiensis, the foliar blight pathogen of Marsilea minuta,/i> L.
Drechslera hawaiiensis is responsible for foliar blight disease in Marsilea minuta L., a common weed of rice. Experiments were conducted for the determination of nutritional and climatic requirements of this pathogen. Five culture media viz. malt extract agar, potato dextrose agar, Richard’s agar, water agar and Czapek Dox agar were used. Potato dextrose agar was found to be the best medium for culturing D. hawaiiensis. Sporulation of D. hawaiiensis was the best on potato dextrose agar medium followed by malt extract agar at 20 to 30°C. All the three pH levels viz. 6, 7 and 8 were found suitable for fungal growth and sporulation. However, the suitability of a particular pH was associated with temperature, culture medium and photoperiod. Both growth and sporulation were affected by photoperiod to which fungal colonies were exposed during incubation. In general, the effect of light on sporulation was more pronounced than the effect on fungal vegetative growth. On water agar and Richard’s agar media, continuous darkness enhanced sporulation. Conversely, on potato dextrose agar and malt extract agar media, 12 h photoperiod was found to be the most suitable for abundant sporulation as compared to continuous dark or continuous light treatments. On Czapek dox agar medium, both continuous darkness and 12 h photoperiod were found to be equally effective for better sporulation. Presently, the interaction of temperature and light had a marked effect on sporulation in D. hawaiiensis. Under complete darkness, 25°C and under 12 h photoperiod, both 25 and 30°C were found to be most suitable for best sporulation in this species.
Keywords: Drechslera hawaiiensis, growth media, light, Marsilea minuta, pH, temperature.