The Dual Nature of Weedy Rice (Oryza sativa f. spontanea): From a Noxious Weed to an Important Genetic Resource for Rice Improvement

Authors

• Rica M. Rentino, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Vanessa Sernicula, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• May O. Palanog, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Roselyn G. Alfetche, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Dan Michael A. Angay, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Francis L. Tejada, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Dexter G. Balboa, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Shaireen M. Angay, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Fatima-Nasra A. Sahadain, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Teodora E. Mananghaya, Plant Breeding and Biotechnology Division, Philippine Rice Research Institute Central Experiment Station, Muńoz, Nueva Ecija
• Karl Vincent J. Jose, Genetic Resources Division, Philippine Rice Research Institute Central Experiment Station, Muńoz, Nueva Ecija
• Liezel C. Llanes, Genetic Resources Division, Philippine Rice Research Institute Central Experiment Station, Muńoz, Nueva Ecija
• Jonathan M. Niones, Genetic Resources Division, Philippine Rice Research Institute Central Experiment Station, Muńoz, Nueva Ecija
• Karla Mae R. Nonog, Plant Breeding and Biotechnology Division, Philippine Rice Research Institute Central Experiment Station, Muńoz, Nueva Ecija
• Frodie F. Waing, Plant Breeding and Biotechnology Division, Philippine Rice Research Institute Central Experiment Station, Muńoz, Nueva Ecija
• Leonilo Gramaje, Plant Breeding and Biotechnology Division, Philippine Rice Research Institute Central Experiment Station, Muńoz, Nueva Ecija
• Albert Christian S. Suner, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Ommal H. Abdulkadi, Philippine Rice Research Institute Negros Station, Murcia, Negros Occidental
• Norvie L. Manigbas, Plant Breeding and Biotechnology Division, Philippine Rice Research Institute Central Experiment Station, Muńoz, Nueva Ecija
• Jose E. Hernandez, University of the Philippines Los Bańos, College, Laguna
• Alvin D. Palanog, Philippine Rice Research Institute Negros Station, Murcia, Negros OccidentalFollow

Publication Date

3-1-2026

Abstract

Weedy rice (Oryza sativa f. spontanea) is becoming a serious threat to rice production in the Philippines, especially in direct-seeding rice areas, owing to its high competitiveness and its similarity to cultivated rice in morphology and ecological requirements. However, weedy rice can be considered both a threat that endangers rice production and an opportunity, as it offers a potential source of novel genes for rice improvement. This study evaluated the extent of weedy rice infestation in direct-seeding areas in the Visayas, measured the phenotypic and genotypic diversity of collected weedy rice ecotypes using simple sequence repeat (SSR) markers, and genotyped them with single nucleotide polymorphism (SNP) trait-based markers for bacterial leaf blight (BLB) and blast resistance genes. Quadrat sampling in major rice-producing areas showed a high to heavy infestation of weedy rice (2% to 14%/m2), possibly one of the primary reasons for low yields in these areas. Weedy rice ecotypes collected and characterized showed a very high phenotypic and genotypic diversity (He = 0.831, I = 1.976), which complicates the development of control measures. Furthermore, the presence of admixtures or ecotypes genetically similar to cultivated and wild rice entails a high adaptive potential of weedy rice that might be seriously considered in the future, especially in developing herbicide-resistant rice, since these ecotypes might serve as genetic bridges. However, identifying ecotypes that possess broad-spectrum resistance genes for BLB (xa5 and Xa23) and blast (Pi54 and Pikh) provides a promising opportunity for breeding durable resistant rice varieties. These findings provide valuable information that can help develop effective control management strategies for weedy rice and highlight its value as an important genetic resource.

Recommended Citation

Rentino, Rica M.; Sernicula, Vanessa; Palanog, May O.; Alfetche, Roselyn G.; Angay, Dan Michael A.; Tejada, Francis L.; Balboa, Dexter G.; Angay, Shaireen M.; Sahadain, Fatima-Nasra A.; Mananghaya, Teodora E.; Jose, Karl Vincent J.; Llanes, Liezel C.; Niones, Jonathan M.; Nonog, Karla Mae R.; Waing, Frodie F.; Gramaje, Leonilo; Suner, Albert Christian S.; Abdulkadi, Ommal H.; Manigbas, Norvie L.; Hernandez, Jose E.; and Palanog, Alvin D. (2026) "The Dual Nature of Weedy Rice (Oryza sativa f. spontanea): From a Noxious Weed to an Important Genetic Resource for Rice Improvement," The Philippine Agricultural Scientist: Vol. 109: No. 2, Article 10.
Available at: https://www.ukdr.uplb.edu.ph/pas/vol109/iss2/10