Abstract
AbstractIn Bangladesh, weeds in transplanted rice are largely controlled by labor-intensive and costly manual weeding, resulting in inadequate and untimely weed control. Labor scarcity coupled with intensive rice production has triggered increased use of herbicides. These factors warrant a cost-effective and strategic integrated weed management (IWM) approach. On-farm trials with transplanted rice were conducted during monsoon (‘Aman’) season in 2016 and 2017 and winter (‘Boro’) season in 2016 to 2017 in agroecological zones 11 and 12 with ten treatments—seven herbicide-based IWM options, one mechanical weed control-based option, and two checks (farmers’ current weed control practice and weed-free)—to assess effects on weed control, grain yield, labor use, and profitability. Compared to farmers’ practice, herbicide-based IWM options with mefenacet + bensulfuron-methyl as preemergence followed by (fb) either bispyribac-sodium or penoxsulam as postemergence fb one hand-weeding were the most profitable alternatives, with reductions in labor requirement by 11 to 25 person-days ha–1 and in total weed control cost by US$44 to 94 ha–1, resulting in net returns increases by US$54 to 77 ha–1 without compromising on grain yield. In contrast, IWM options with bispyrbac-sodium or penoxsulam as postemergence application fb one hand-weeding reduced yields by 12% to 13% and profits by US$71 to 190 ha–1. The nonchemical option with mechanical weeding fb one hand-weeding performed similarly to farmers’ practice on yield and profitability. We suggest additional research to develop feasible herbicide-free approaches to weed management in transplanted rice that can offer competitive advantages to current practices.
Highlights
Bangladesh, with a current population of 165 million, is largely self-sufficient in rice production, but to sustain self-sufficiency by 2030 and to feed a projected population of 186 million people, an increase of 20% in rice production will be necessary (Timsina et al 2018)
Rice is cultivated throughout the year with three distinct growing seasons popularly known as pre-monsoon or ‘Aus’ rice grown from April to August, monsoon or ‘Aman’ rice from June to November, and winter or ‘Boro’ rice from December to May, covering 9%, 49%, and 42% of total rice area, respectively (BBS 2017)
We evaluated herbicides that are approved in the Pesticide Evaluation Report and Safer-Use Action Plan (PERSUAP) in different combinations with different MOAs, applied as preemergence, postemergence, or both pre- and postemergence, or used as mixtures by integrating manual and mechanical weeding to identify effective, affordable, and safer options for weed control in PTR as compared to farmers’ current weed management practices
Summary
Bangladesh, with a current population of 165 million, is largely self-sufficient in rice production, but to sustain self-sufficiency by 2030 and to feed a projected population of 186 million people, an increase of 20% in rice production will be necessary (Timsina et al 2018). In Bangladesh and much of tropical and subtropical Asia, rice is predominantly established under wet-tilled or “puddled” soil conditions followed by transplanting of seedlings (PTR). Weeds are among the main biological constraints to realizing attainable rice yield potential. They significantly reduce profitability (Ahmed et al 2014; BRRI 2018; Chauhan 2012; Kumar et al 2013). In tropical Asia, yield losses due to weeds in lowland rice range from 10% to 20% (Savary et al 2012). In Bangladesh, the climate and edaphic conditions are highly favorable for weed growth IP address: 54.89.244.222, on 19 Jan 2022 at 10:05:43, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms.
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