Effects of Different Culture Media, pH, Carbon, and Nitrogen Sources on the Growth of Helminthosporium oryzae, Causing Brown Spots on Rice

Background and Objective: In order to study the fungus growth, pathogenicity, and development of control methods, it is essential to cultivate it in a controlled setting using nutritional media and different favorable sources. Helminthosporium oryzae, the causative agent of rice brown spot, was assessed in relation to different nutrient media, pH, nitrogen, and carbon sources. Materials and Methods: The bio-efficacy of the nutritional media against the fungus was evaluated using potato dextrose agar, cornmeal agar, carrot sucrose-agar, and rice polish agar. The growth of the brown spot pathogen was examined in relation to several pH levels (4, 5, 6, 7, 8, and 9), glucose, sucrose, maltose, fructose, lactose, and mannitol as carbon sources, and sodium nitrate, barium nitrate, lead nitrate, potassium nitrate, and ammonium nitrate as nitrogen sources. The laboratory study employed a Completely Randomized Design (CRD) to examine the experimental data. The one-way ANOVA test was used to evaluate the means’ significance. Data analysis was conducted using the Statistical Analytical System (SAS) version 9.4 on the computer. Results: According to the study, the best media for mycelial development were potato dextrose agar and rice polished agar. The pathogen’s growth was evaluated at different pH levels, and the results indicated that mycelial growth was most supported by pH values between 6 and 7, while pH 4 hindered mycelial growth seven days after inoculation. The best nitrogen and carbon sources that were determined to be appropriate for the mycelial growth were potassium nitrate and sucrose. Conclusion: These findings will help to improve the understanding of the pathogen’s basic physiology and pave the way for the development of efficient methods for managing rice brown spot.