ABSTRACT
Comparative study of disease tolerance on six rice varieties against bacterial leaf blight and bacterial panicle blight

Fatma Azwani Abdul Aziz1*, Azimah Hamidon1, Mohd As’wad Abdul Wahab2, Norida Mazlan1, 2, Siti Izera Ismail1, 2, and Nor Azura Husin3
 
Rice (Oryza sativa L.) production is significantly threatened by bacterial leaf and panicle blight, which can cause yield losses of up to 70% and 50%, respectively. Several rice cultivars (Putra 1, Putra 2, IS21, CL2, Siraj 297, MRQ 76) were evaluated for tolerance to bacterial leaf blight (BLB) and bacterial panicle blight (BPB) under inoculations with Xanthomonas oryzae pv. oryzae (BLB), Burkholderia glumae (BPB), a combination of both, and a control. Key parameters, including plant height, number of tillers, leaf and lesion length, disease incidence, and disease severity, were measured at intervals from 10 to 60 d after transplanting (DAT). Results indicated significant variability in disease tolerance. ‘Putra 2’ recorded the tallest plant height (79.1 cm under BLB), while ‘IS21’ showed the shortest lesion lengths (13.0 cm under BLB). Conversely, ‘Siraj 297’ and ‘MRQ 76’ recorded the longest lesions (24.0 cm and 23.3 cm, respectively) and the highest disease incidence (> 38% under BLB). Disease severity peaked in ‘Siraj 297’ (score 3.6), whereas ‘Putra 1’ and ‘IS21’ remained lower (2.0-2.3). ‘CL2’ exhibited moderate lesion development but recorded the lowest incidence under BPB (16.6%). Overall, ‘Putra 1’, ‘Putra 2’ and ‘IS21’ showed greater resilience with minimal growth changes and shorter lesion lengths, while ‘Siraj 297’ and ‘MRQ 76’ were more susceptible. These findings emphasize the importance of selecting suitable cultivars for disease-prone regions to minimize losses, while providing agronomists and farmers with practical insights for variety selection and disease management. It also highlights the need for continued cultivar development to improve resistance and sustain productivity.
Keywords: Bacterial leaf blight, bacterial panicle blight, BLB, BPB, Burkholderia glumae, disease tolerance, Oryza sativa, Xanthomonas oryzae pv. oryzae.
1Universiti Putra Malaysia, Institute of Tropical Agriculture and Food Security, 43400 UPM Serdang, Selangor, Malaysia.
2Universiti Putra Malaysia, Faculty of Agriculture, 43400 UPM Serdang, Selangor, Malaysia.
3Universiti Putra Malaysia, Faculty of Computer Science and Information Technology, 43400 UPM Serdang, Selangor, Malaysia.
*Corresponding author (fatma@upm.edu.my)