Phenotypic screening of advanced breeding lines against bacterial blight (BB) disease in rice

Rice is an important staple crop globally, particularly in Bangladesh, which is vital in ensuring food security. Biotic challenges pose a significant risk to the cultivation of rice. However, rice cultivation in Bangladesh faces significant challenges due to 32 different diseases affecting the rice yield. Among them, bacterial leaf blight caused by Xanthomonas oryzae pv oryzae (Xoo) is significant diseases responsible for substantial yield losses. Despite extensive efforts, effective control measures for bacterial blight diseases have not been identified. Therefore, developing disease-resistant rice varieties represents the most efficient and environmentally friendly approach to combat these diseases. In order to assess the physical impact, an experiment was carried out at the experimental plot (23°59'27.5"N 90°24'18.3"E) (on station) of Plant Pathology Division, BRRI, Gazipur, Bangladesh. A total of 295 breeding lines were examined by introducing Bacterial leaf blight culture with most virulence isolate (BXo822) through the leaf clipping technique. To identify new resistant source(s) against BB, 295 materials including resistant, susceptible and standard checks (BRRI dhan63 & BRRI dhan81) were screened against bacterial blight pathogen in Aman 2022 and Boro 2022-23. In Aman 2022, at first 14 days after inoculation among 295 breeding lines 168 advanced breeding lines are found as resistant, 75 advanced breeding lines are found as moderately resistant and 40 as moderately susceptible against bacterial blight disease. Other genotypes were found as susceptible to highly susceptible to bacterial blight disease. In Boro 2022-23, at first 14 days after inoculation among 295 breeding lines 41 advanced breeding lines are found as highly resistant, 74 advanced breeding lines are found as resistant, 16 advanced breeding lines are found as moderately resistant and 19 as moderately susceptible against bacterial blight disease. Other genotypes were found as susceptible to highly susceptible to bacterial blight disease. The resistant lines identified in this study could be recommended as bacterial blight resistant varieties or be utilized as donor parents for future resistant breeding program. Also perform better in the field trials and further in the farmers fields with the good level of bacterial blight resistance.