Efficacy of pre- and post-emergence herbicide combinations on weed control in no-till mechanically transplanted rice

Abstract

No-till mechanized-transplanted rice was evaluated for different combinations of pre- and post-emergence herbicides to determine feasible, economically viable weed management options to control complex weed flora in rice fields. All pre-emergence herbicides significantly reduced the population of grassy weeds; of these, pendimethalin resulted in the greatest reductions (83%) at 15 days after transplanting (DAT). Among five post-emergence herbicide treatments, the combination of bispyribac-sodium (10%SP) + pyrazosulfuron (10%WP) was found to be the most effective in controlling all weed flora at both 35 and 55 DAT. The sequential application of pendimethalin (pre-emergence) followed bispyribac-sodium + pyrazosulfuron (post-emergence) resulted in significantly higher rice grain yield (4.4 t-ha⁻¹) and relative gross-margin (417 USD-ha⁻¹) than all other treatments. A strong negative correlation was observed between rice grain yield and weed biomass, and a strong positive correlation between rice grain yield and weed control efficiency. Our findings demonstrate the potential to combine pre- and post-emergence herbicides in no-till mechanized-transplanted rice; these findings have applications globally in regions where rice is established by no-till or mechanized transplanting.

Keywords:

• herbicide
• no-till or unpuddled
• mechanized transplanted rice
• weed biomass and density
• weed control efficiency

Acknowledgements

This research was conducted as part of the Sustainable and Resilient Farming Systems Intensification in the Eastern Gangetic Plains (SRFSI) project (CSE/2011/077) funded by the Australian government through the Australian Centre for International Agricultural Research and the Department of Foreign Affairs and Trade. We are grateful to Uttar Banga Krishi Viswavidyalaya for facilitating the field trials, laboratory analyses and providing support staff. Thoughtful comments from two anonymous reviewers improved this manuscript.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by the Australian Centre for International Agricultural Research [CSE/2011/077]; Department of Foreign Affairs and Trade, Australian Government [CSE/2011/077].