Overview
Background
Dr. Jhoana Opena, a seasoned researcher, joined The University of Queensland as a Postdoctoral Research Fellow in 2021. Dr. Opena has over 18 years of experience in research related to Integrated Pest Management (IPM) in vegetables and weed management within rice-based cropping systems across Australia, the Philippines, Cambodia, and Lao PDR. Previously, she worked as an Associate Scientist in the Weed Science group at the International Rice Research Institute and was appointed as an Adjunct Associate Professor at the University of the Philippines in Los Baños. She successfully completed her Doctor of Philosophy in Agriculture at Charles Sturt University in Wagga Wagga, Australia, in 2021. Currently, she is working on an ACIAR project entitled “Weed Management Techniques for Mechanized and Broadcast Lowland Crop Production Systems in Cambodia and Lao PDR.”
Availability
- Dr Jhoana Opena is:
- Available for supervision
Qualifications
- Bachelor, University of the Philippines Los Baños
- Masters (Coursework), University of the Philippines
- Doctor of Philosophy, Charles Sturt University
Research interests
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Weed management in rice and rice-based cropping systems
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Weed ecology
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Integrated weed management in direct seeded rice systems
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Weed population dynamics
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Allelopathy and its application for weed management
Research impacts
Through a five-year ACIAR program in Laos and Cambodia, our research co-designed and field-tested integrated weed management (IWM) for mechanised direct-seeded rice, working with partners across 14 villages. The packages (good seed, precise seeding, early water management, mechanical tools, mungbean intercropping, and judicious herbicides) reduced weed-seed contamination by ~90% (≈290 → ~30 seeds/kg) without reducing head-rice yield, improving grain quality and farm returns. Addressing baseline reliance on herbicides (≈43% of farmers in Laos; ~80% in Cambodia), we shifted practice toward safer, targeted use—including drone applications—while training 49 Master Trainers and delivering gender-responsive farmer training that increased women’s confidence in weed ID and safe handling. The work also informed draft national drone guidelines (Cambodia) and herbicide-use guidance (Laos), providing a scalable, gender-inclusive pathway to higher profitability, reduced chemical dependence, and more sustainable rice systems.
Works
Search Professor Jhoana Opena’s works on UQ eSpace
2023
Conference Publication
Unlocking women's potential for effective weed management in rainfed lowlands: A Cambodian perspective
Lim, Sophornthida, Chea, Sareth, Palaniappan, Gomathy, Opena, Jhoana and Mitchell, Jaquie (2023). Unlocking women's potential for effective weed management in rainfed lowlands: A Cambodian perspective. International Rice Congress 2023, Manila, Philippines, 16-19 October 2023. Zenodo. doi: 10.5281/zenodo.10398235
2023
Conference Publication
Promoting gender equality amongst rice farmers: Insights from ACIAR funded projects in Laos, Cambodia, and Vietnam
Palaniappan, Gomathy, Chea, Sareth, Lim, Sophornthida, Bouahom, Bounthanom, Nguyen, Minh Anh, Nguyen, Binh Thanh, Nguyen, Tin Hong, Opena, Jhoana and Mitchell, Jaquie (2023). Promoting gender equality amongst rice farmers: Insights from ACIAR funded projects in Laos, Cambodia, and Vietnam. International Rice Congress 2023, Manila, Philippines, 16-19 October 2023. Zenodo. doi: 10.5281/zenodo.10398686
2023
Conference Publication
Designing best weed management practices for mechanized rainfed and irrigated direct seeded rice systems in Cambodia and Lao PDR
Opena, Jhoana and Mitchell, Jaquie (2023). Designing best weed management practices for mechanized rainfed and irrigated direct seeded rice systems in Cambodia and Lao PDR. International Rice Congress 2023, Manila, Philippines, 16 - 19 October 2023. Zenodo. doi: 10.5281/zenodo.10398266
2023
Conference Publication
Allelopathic pasture legumes to manage barnyard grass in drill sown rice in temperate Australia
Opena, Jhoana, Pratley, Jim, McCormick, Jeffrey, Wu, Hanwen and Lemerle, Deirdre (2023). Allelopathic pasture legumes to manage barnyard grass in drill sown rice in temperate Australia. 28th Asian Pacific Weed Science Society Conference, Phuket, Thailand, 26-29 November 2023.
2023
Conference Publication
Integrated weed management in direct seeded rice using stale seedbed techniques and pre-emergence herbicide under rainfed lowland rice in Cambodia
Lim, Vanndy, Touch, Veasna, Vial, Leigh, Sodany, Srom, Phoeun, Chetra, Sun, Chanketya, Opena, Jhoana and Mitchell, Jaquie (2023). Integrated weed management in direct seeded rice using stale seedbed techniques and pre-emergence herbicide under rainfed lowland rice in Cambodia. 28th Asian Pacific Weed Science Society Conference, Phuket, Thailand, 26-29 November 2023.
2023
Conference Publication
Magnitude of weed problems in direct-seeded rice systems in Lao PDR
Manivong, Phatsalakone, Xangsayasane, Phetmanyseng, Opena, Jhoana, Lemerle, Deirdre and Mitchell, Jaquie (2023). Magnitude of weed problems in direct-seeded rice systems in Lao PDR. 28th Asian Pacific Weed Science Society Conference, Phuket, Thailand, 26-29 November 2023.
2023
Conference Publication
Current and integrated weed management prospects in Cambodia’s direct seeded rice production
Pel, Dora, Lim, Sophornthida, Chea, Sareth, Palaniappan, Gomathy, Opena, Jhoana and Mitchell, Jaquie (2023). Current and integrated weed management prospects in Cambodia’s direct seeded rice production. 28th Asian Pacific Weed Science Society Conference, Phuket, Thailand, 26-29 November 2023.
2023
Conference Publication
Baseline weed seedbank survey in direct-seeded rice systems in Lao PDR
Lovanxay, Douangsavanh, Xangsayasane, Phetmanyseng, Opena, Jhoana, Lemerle, Deirdre and Mitchell, Jaquie (2023). Baseline weed seedbank survey in direct-seeded rice systems in Lao PDR. 28th Asian Pacific Weed Science Society Conference, Phuket, Thailand, 26-29 November 2023.
2023
Conference Publication
Weed seed contamination of rice from a drill-seeded intercropping demonstration compared with farmers’ broadcast rice in Lao PDR
Vongxayya, Khamtay, Opena, Jhoana, Xangsayasane, Phetmanyseng, Lemerle, Deirdre and Mitchell, Jaquie (2023). Weed seed contamination of rice from a drill-seeded intercropping demonstration compared with farmers’ broadcast rice in Lao PDR. 28th Asian Pacific Weed Science Society Conference, Phuket, Thailand, 26-29 November 2023.
2023
Conference Publication
Genetic variability for rice tolerance to anaerobic germination in the Laos gene bank
Homsengchanh, Laeh, Xangsayasane, Phetmanyseng, Opena, Jhoana and Mitchell, Jaquie (2023). Genetic variability for rice tolerance to anaerobic germination in the Laos gene bank. International Rice Congress 2023, Manila, Philippines, 16-19 October 2023.
2023
Conference Publication
Weed seedbank in direct-seeded rice systems in Cambodia
Sokvisal, Kong, Sathya, Khay, Opena, Jhoana, Lemerle, Deirdre and Mitchell, Jaquie (2023). Weed seedbank in direct-seeded rice systems in Cambodia. 28th Asian Pacific Weed Science Society Conference, Phuket, Thailand, 26-29 November 2023.
2022
Conference Publication
Current weed management practices and obstacles in rainfed lowland direct seeded rice systems in Southern Cambodia
Lim, Sophornthida, Chea, Sareth, Palaniappan, Gomathy, Opena, Jhoana and Mitchell, Jaquie (2022). Current weed management practices and obstacles in rainfed lowland direct seeded rice systems in Southern Cambodia. 8th International Weed Science Congress, Bangkok, Thailand, 4-9 December 2022.
2022
Conference Publication
Rice weed seed contamination of farmers retained and certified seeds in Lao PDR
Vongxayya, Khamtay, Opena, Jhoana, Xangsayasane, Phetmanyseng, Lemerle, Deirdre and Mitchell, Jaquie (2022). Rice weed seed contamination of farmers retained and certified seeds in Lao PDR. 8th International Weed Science Congress, Bangkok, Thailand, 4-9 December 2022.
2022
Conference Publication
Screening of rice genotypes for their weed competitiveness in Lao PDR
Homsengchanh, Laeh, Xangsayasane, Phetmanyseng, Opena, Jhoana, Lemerle, Deirdre and Mitchell, Jaquie (2022). Screening of rice genotypes for their weed competitiveness in Lao PDR. 8th International Weed Science Congress, Bangkok, Thailand, 4-9 December 2022.
2022
Conference Publication
Weed management in lowland rice cropping systems in Cambodia and Lao PDR
Opena, Jhoana and Mitchell, Jaquie (2022). Weed management in lowland rice cropping systems in Cambodia and Lao PDR. TropAg International Agriculture Conference, Brisbane, QLD Australia, 31 October - 2 November 2022.
2022
Conference Publication
Weed management and gender roles in lowland rice production systems in Lao PDR
Bouahom, Bounthanom, Palaniappan, Gomathy, Abdul Aziz, Ammar, Opena, Jhoana, Xangsayasane, Phetmanyseng and Mitchell, Jaquie (2022). Weed management and gender roles in lowland rice production systems in Lao PDR. 8th International Weed Science Congress, Bangkok, Thailand, 4-9 December 2022.
2022
Conference Publication
Light and temperature affect the germination of barnyard grass in drill sown rice in Australia
Opena, Jhoana, Pratley, Jim, McCormick, Jeffrey, Wu, Hanwen and Lemerle, Deirdre (2022). Light and temperature affect the germination of barnyard grass in drill sown rice in Australia. 8th International Weed Science Congress, Bangkok, Thailand, 4-9 December 2022.
2021
Journal Article
Potential of winter pasture legume in rice rotations to mitigate barnyard grass (Echinocloa crus-galli) impacts in temperate Australia
Opena, Jhoana, Pratley, James, Lemerle, Deirdre, Wu, Hanwen and McCormick, Jeffrey (2021). Potential of winter pasture legume in rice rotations to mitigate barnyard grass (Echinocloa crus-galli) impacts in temperate Australia. Agricultural Science, 79-91.
2021
Other Outputs
Impacts of pasture legume phase on the seed bank of barnyard grass in drill sown rice
Opena, Jhoana, Pratley, James, Lemerle, Deirdre, Wu, Hanwen and McCormick, Jeffrey (2021). Impacts of pasture legume phase on the seed bank of barnyard grass in drill sown rice. Wagga Wagga, NSW, Australia: AgriFutures Australia.
2021
Other Outputs
Impacts of pasture legume phase on the seed bank, establishment and growth of barnyard grass (Echinochloa crus-galli) in drill sown rice
Opena, Jhoana (2021). Impacts of pasture legume phase on the seed bank, establishment and growth of barnyard grass (Echinochloa crus-galli) in drill sown rice. PhD Thesis, School of Agricutural, Environmental and Veterinary Sciences, Charles Sturt University.
Supervision
Availability
- Dr Jhoana Opena is:
- Available for supervision
Looking for a supervisor? Read our advice on how to choose a supervisor.
Available projects
Supervision history
Current supervision
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Doctor Philosophy
Impact of pesticide residues on food safety and soil quality in direct seeded rice systems
Associate Advisor
Other advisors: Dr Dara Daygon, Professor Jaquie Mitchell
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Doctor Philosophy
GIS and remote sensing for improved weed management in direct seeded rice
Associate Advisor
Other advisors: Professor Jaquie Mitchell, Professor Ammar Abdul Aziz, Dr Md. Ali Akber
Media
Enquiries
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