Emergence of Nigrospora Leaf Blight as Major Biotic Stress in South Eastern Coastal Region of India

Background: Nigrospora is one of the diversified pathogens with wide host range. Endophytic nature of Nigrospora oryzae has been reported previously. Daily variations in the climate led to the emergence of virulent infections from previously expressed weak ones. Nigrospora oryzae infestation comes as a major biotic stress under this present investigation. Methods: A study was conducted to examine the variability of Nigrospora oryzae by collecting isolates from various locations in the south coastal region of Odisha. The level of virulence was assessed and analyzed between 2021 and 2023 to anticipate the emergence and progression of disease. The pathogen was identified using molecular techniques through ITS-r DNA sequencing method. Result: Disease incidence was observed as a critical blast-like appearance, but greater in size, distinguishing it from blast. In the experiment, incomplete filling of grains was highest in MTU-7029 (39.73 plant-1) followed by Niranjana and Gobindobhog; disease incidence was recorded to be highest in Niranjana (60.03%) followed by MTU-7029 and Barsha; and grain yield plant-1 was observed to be highly affected in Gobindobhog (14.58 g plant-1 followed by MTU-7029 and Niranjana. Molecular confirmation was established by ITS-rDNA sequencing, resulted sequence NO 9 (528 bp)- OP592217 and NO 15 (519 bp)- OP592218, exactly matches gene bank accession numbers- MH748173 (India) and ON514037 (India) of Nigrospora database, with 99% accuracy.