Evaluation of the emergence of imidazolinone resistant weedy rice (Oryza Sativa l.) In Malaysia

• Main Authors: Bzour, M., Zuki, F. M., Mispan, Muhamad Shakirin
• Format: Article
• Published: Corvinus Univ Budapest 2020
• Subjects: TD Environmental technology. Sanitary engineering
• Online Access: http://eprints.um.edu.my/28897/
• Institution: Universiti Malaya

The Clearfield (R) Rice Production System (CPS) technology successfully manages weedy rice infestation and increases rice production in Malaysia. However, there were concerns on the recurring presence of weedy rice in the CPS fields in recent years, suspecting that weedy rice has become resistant to the imidazolinone (IMI) herbicide. This research was designed to evaluate the occurrence of herbicide resistant weedy rice in the CPS fields. A total of 17 weedy rice biotypes were collected and assessed for resistance to IMI (imazapic + imazapyr) during germination and vegetative stages using different herbicide concentrations. Different dosages of IMI herbicide only reduced germination rate by similar to 30% but significantly decreased the weedy rice seedlings' viability. Low viability rate for commercial (13.9 +/- 13.8%) and double (7.3 +/- 4.1%) herbicide dose indicated application of IMI herbicide as pre-emergence herbicide was effective to control weedy rice. The application of IMI herbicide at later stage after the recommended period increased weedy rice escape potential in the CPS fields by 64.7% to 76.5% for one- and two-dose applications, respectively. There is a possibility that weedy rice in Malaysia has developed certain levels of resistance towards IMI herbicide. Stringent ecological risk evaluation of CPS is needed to mitigate the development of herbicide resistant weedy rice in the future.