Weed Management in Aerobic Rice in Northwestern Indo-Gangetic Plains

Abstract

Aerobic rice systems, wherein the crop is established via direct seeding in non-puddled, non-flooded fields, are among the most promising approaches for saving water and labor. However, aerobic systems are subject to much higher weed pressure than conventionally puddled transplanted rice (CPTR). Experiments were conducted for two years to develop effective and economical methods for managing weeds in aerobic rice grown by direct seeding rather than by conventional transplanting method. The proportion of mean grass-weed dry matter was 28.3% more in aerobic direct-seeded rice (ADSR) as compared to CPTR. Both weed density and dry weight were negatively correlated with rice grain yield. ADSR treatment produced yield similar to CPTR treatment when weeds were controlled effectively. Post-emergence application of bispyribac Na 25 g/ha and penoxsulam 25 g/ha could effectively control all the weeds in ADSR. Irrigation water productivity remained statistically the same in both ADSR and CPTR under the weed-free situation or when bispyribac Na herbicide was applied as post-emergence because of effective weed control in ADSR. The variation in net profitability between the ADSR and CPTR decreased with herbicide treatments, viz., Bispyribac Na, followed by penoxsulam and sequential application of pretilachlor and metsulfuron.

Weed dynamics as influenced by tillage system, sowing time and weed competition duration in dry-seeded rice

“…In the present study, the contribution of D. aegyptium, E. colona, and E. crus-galli to total weed density was higher than other grasses. The proportion of grasses was 19% higher during second year of DSR at Ludhiana, India (Mahajan et al, 2009). Jaya Suria et al (2011) from their field trials at Penang, Malaysia, concluded that grasses were the most dominant category of weeds in DSR constituting approximately 80% of the weed community.…”

Weed control in dry direct-seeded rice using tank mixtures of herbicides in South Asia

“…Sometimes, farmers missed the optimum application time of preemergence herbicides due to onset of erratic rains at that time or due to other reasons. Weed flora in DSR is very complex and a single use of a pre-or post-emergence herbicide does not provide effective weed control in DSR (Mahajan et al, 2009). The use of herbicide combinations, whether the herbicides are applied simultaneously (tank-mixed) or sequentially, generally improves weed control compared with a single herbicide application .…”

“…In the north-west India, due to ordinances (not to transplant paddy before 1st June) passed by some states, the window period (10e30th June) for rice planting has become narrow and there is a scarcity of labour because of huge demand, particularly at the time of transplanting. Delayed transplanting of rice in July not only causes reductions in rice yield (Mahajan et al, 2009) but also become an obstacle for the timely sowing of the subsequent wheat (Triticum aestivum L.) crop. This led to high wage rates at the time of rice transplanting because of limited labour availability.…”

“…Despite several advantages of DSR, it is subjected to much higher weed pressure than the conventional puddled transplanted rice systems (Chauhan, 2012), in which weeds are suppressed by standing water and transplanted rice seedlings, which have a "headstart" over germinating weed seedlings (Moody, 1983). Aerobic soil conditions and alternate wetting and drying in DSR are conducive to the germination and growth of weeds, causing grain yield losses of up to 80% (Mahajan et al, 2009). Thus, an efficient and timely weed control is crucial for the success of DSR.…”

Weed management through herbicide application in direct-seeded rice and yield modeling by artificial neural network

“…Pre-emergence application of pendimethalin followed by post-emergence application of bispyribac-sodium at 15 days after sowing (DAS) was most effective for controlling weeds in DSR (Mahajan et al, 2009). In another study, application of oxadiazon at 2 DAS followed by fenoxaprop + ethoxysulfuron applied at 28 DAS fetched the best result in DSR (Chauhan & Opena, 2013).…”