English
Rice brown spot disease, caused by Bipolaris oryzae, is a major constraint to rice production worldwide and has been exacerbated under climate change. Unlike many other foliar diseases, brown spot progresses rapidly, with visible symptoms developing within only three days under controlled conditions (31 °C, 100% relative humidity). This rapid onset makes it suitable for efficient pathogenicity assays but also presents challenges in disease quantification, as lesions are typically small and scattered, complicating manual assessment of lesion area. In this study, approximately 150 long-grain rice accessions were screened for resistance to brown spot disease, and a novel automated system was developed to measure lesion area percentage with high accuracy. The system demonstrated a precision of 90–100%, substantially improving reliability and throughput compared with manual scoring. This methodological advancement provides a robust framework for evaluating resistance to B. oryzae, enabling the rapid and accurate identification of resistant germplasm and supporting future rice breeding and disease management programs. [This work was supported by the Rural Development Administration of Korea (RS-2025-02214096)]
