Effect of different Media, pH Levels and Temperature on Growth and Sporulation of Microdochium sorghi causing Zonate Leaf Spot of Sorghum

Author: Banothu Chandrashekar, Yogendra Singh, B.K. Namriboi, Senthil Kumar S. and Marjit Chandam

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Abstract

Sorghum (Sorghum bicolor L. Moench) is the 5th major cereal crop, used as a food, feed, fiber, and bioenergy production. Among the diseases affecting sorghum, Zonate leaf spot caused by Microdochium sorghi has been considered a minor issue in recent decades. However, due to the impact of climate change, this pathogen has begun to cause economic damage to both forage and grain sorghum crops. To develop effective management strategies against this disease, it is crucial to understand the cultural characteristics of the pathogen and how it responds to various physiological and temperature conditions. This study investigates the in vitro effects of different culture media, pH levels, and temperature on the mycelial growth and sporulation of M. sorghi. Among the 10culture media examined, the pathogen displayed the highest mycelial growth on Oat Meal Agar (with a diameter of 90mm), followed by Potato Dextrose Agar (85.3 mm), Rye Agar Type-A (82.1 mm), and Corn Meal Agar (77.3 mm) while the least growth was observed on L- Asparagine Media (31.6mm). Furthermore, experiments were conducted using Oat Meal Agar to evaluate the influence of different temperature (15°C, 20°C, 25°C and 30°C) and pH levels (5.0, 5.5, 6.0, 6.5, 7.0, 7.5 and 8.0). The most optimum condition for promoting M. sorghi growth (90mm) were identified at pH 6.5 and pH 7.0 both at temperature 30°C. Notably, these conditions were also associated with a significant enhancement in sporulation.

Keywords

Media, Microdochium sorghi, pH, Sorghum, Sporulation, Temperature, Zonate

Conclusion

Microdochium sorghi isolated from diseased sorghum leaves exhibited varying growth responses to different culture media, pH levels and temperature. Oat Meal Agar (OMA) emerged as the most suitable medium for M. sorghi growth, yielding a substantial colony diameter of 90.0 mm. Remarkably, OMA also provided the most conducive conditions for sporulation. Furthermore, experiments on OMA highlighted that pH levels of 6.0 and 6.5, combined with a temperature of 30°C, were optimal for achieving a maximum colony diameter of 90.0 mm. Deviations from this pH range with extreme acidity and alkalinity, as well as temperatures below 30°C were unfavorable for M. sorghi growth and sporulation. These findings will provide valuable insights into the culturing and management of M. sorghi.

References

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How to cite this article

Banothu Chandrashekar, Yogendra Singh, B.K. Namriboi, Senthil Kumar S. and Marjit Chandam (2023). Effect of different Media, pH Levels and Temperature on Growth and Sporulation of Microdochium sorghi causing Zonate Leaf Spot of Sorghum. Biological Forum – An International Journal, 15(9): 1074-1077.