Synergistic Effect of Abiotic Environment on Growth of Macrophomina phaseolina Causing Charcoal Rot Disease of Sesame [(Sesamum indicum L.) cv. Prachi]

Temperature plays major role in growth of fungus. Climate change response of the current biotic stresses, particularly fungi-related diseases in oilseeds is a major global issue. Macrophomina phaseolina is the causal agent of charcoal rot (stem and root rot/MSR) disease of sesame, resulting in large yield losses globally. Evaluation of physiological characteristics are very important to know the behaviour of the pathogen, which is helpful for it’s’ management.

Aim: The purpose of the current investigation was to evaluate the impact of temperature, pH and different culture media on the growth of Macrophomina phaseolina the disease causing pathogen of sesame

Methodology: In-vitro experiments conducted to investigate the physiological characteristics of the devastating pathogen of sesame M. phaseolina. Onefield survey was conducted and diseased samples collected from the predominant areas of Odisha. The fungus was isolated by using PDA medium and incubated at different range of temperatures to show the effect. The mycelial growth was also tested in different pH levels. The cultural characteristics were studied using three culture media i.e. potato dextrose agar, oat meal agar and host leaf extract agar.

Results: The results showed that there is no growth of pathogen or it is very negligible in 10–250C temperature in 24 and 48 hours. 25 - 350C temperature is the optimum temperature for the pathogen to grow and above 350C temperature the growth ceased. Similarly, in case of pH, 6.5 is the suitable pH for the M. phaseolina to grow the highest. Among the culture media the pathogen attains its highest growth rate within five days of isolation in potato dextrose agar and the oat meal agar showed better result for the morphological characters.

Conclusion: Physiological studies showed that, sesame stem and root rot pathogen Macrophomina phaseolina prefers high temperature i.e. 30-35oC and pH 6.5 grow significantly as well as for disease development. Also, the in-vitro study on different culture media showed the growth rate is high in PDA medium but the morphological characters showed better result in OMA medium.