Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Long-term Sustainability in Weed Management for Direct Seeding of Rainfed Rice

A. M. Mortimer
School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, UK

M. A. Mazid
Bangladesh Rice Research Institute, Regional Station, Rangpur, Bangladesh

C. R. Riches
Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK.

Abstract/ Executive Summary:

Successful weed management for direct-seeded rice depends on herbicide use to protect crop yields from weed competition. In irrigated cropping environments, this has a tendency to lead to progressive changes in the weed flora toward intransigent competitive rice weeds. A four-year comparative study of direct seeding and transplanting in the Barind indicated that the weed flora was responsive to an alteration in crop establishment method but that the composition of the target weed community under all methods had significant similarities. This is argued to be a consequence of seasonal variation in rainfall and flooding regimes. The implications for developing sustainable weed management practices with the use of early postemergence herbicides are discussed.

Keywords: Weed, Weed flora, Weed relation to crop, Weed management.

Location: In Bangladesh

Start Date: 00-00-2001

End Date: 00-00-2004

Program Area: Pest Management

Commodity: Weed management, Rainfed rice

Objectives:

To Identifying the factors determining the composition and size of this weed flora in relation to crop and weed management.

Methodology:

As described elsewhere (Mazid et al 2006; this volume), an experimental comparison of rice establishment methods on rice yields and weed responses was made in successive years from 2001 to 2004. These methods were (1) transplanted rice—soil puddled prior to transplanting and plots hand-weeded twice at 30 and 45 days after transplanting (DAT); (2) direct-seeded rice (DSRm)—soil plowed prior to dry seeding (2001 and 2004) or plowed and puddled before direct seeding of pregerminated seed (2002 and 2003) in rows by hand with hand weeding at 21, 33, and 45 days after sowing; and (3) direct-seeded rice with chemical weed control (DSRh)—as above but with oxadiazon (375 g a.i. ha–1) applied 2–4 days after seeding with one hand weeding at 33 days after sowing (DAS). With failure in the development of the monsoon in 2003, transplanting was delayed substantially until September and the crop was established only for experimental purposes. Data from this experiment are discussed only for the 2002 and 2004 seasons. Measurements of the water table began in the field experiment in relation to the intensity of the onset of the monsoon with the use of fixed pizometers that extended 20 mm above ground. No standing water was observed prior to the first recorded measurement in each season. Four nutrient regimes were applied in factorial combination with other treatments in the field experiment. These were (kg ha–1) (1) single superphosphate, 40 P + 40 K; (2) compound, 60 N + 40 P + 40 K; (3) farmyard manure (FYM) + inorganic fertilizer totaling 60 N + 50 P + 50 K; and (4) diammonium phosphate (18% N) + Guti slow-release urea (45% N) totaling 43 N + 40 P + 40 K. At the conclusion of the experiment, bulk soil samples were taken from individual plots to a depth of 20 cm and soil nutrient analysis was completed for total organic matter (combustion), potassium (Olsen method, atomic absorption), total N (Kjeldahl), and phosphorus, sulfur, boron, and zinc (spectrophotometrically following acid digestion). Three replicate soil samples (each 1,000 cm3) were taken from individual plots on each of two occasions, after rice cropping in 2000 and 2002. Soil was then dried and samples pooled according to plot treatment with thorough mixing. Soil from the 2000 field sampling was stored until 2003. Samples (1 kg) of mixed soil for each sample year were then spread according to plot treatments in shallow trays that were watered to either permanently maintain saturated or aerobic conditions. Emerging seedlings were identified by species, counted, and removed. Soil was then stirred to promote a second and third flush. Data were pooled at the plot level to provide an overall estimate of the size of the seed bank for each recorded species.

Source of Information: International Rice Research Institute (IRRI), 2008. ISBN 978-971-22-0229-2

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The weed flora in the study region was typically diverse, including grass, sedge, and broadleaf species. These included ubiquitous major weeds of rice such as Cyperus rotundus, C. iria, C. diffusa, Ischaemum rugosum, Echinochloa colona, E. crus-galli, and Monochoria vaginalis. In irrigated cropping environments, this has a tendency to lead to progressive changes in the weed flora toward intransigent competitive rice weeds. A four-year comparative study of direct seeding and transplanting in the Barind indicated that the weed flora was responsive to an alteration in crop establishment method but that the composition of the target weed community under all methods had a significant similarity. This is argued to be a consequence of seasonal variation in rainfall and flooding regimes. The implications for developing sustainable weed management practices with the use of early postemergence herbicides are discussed.

Knowledge Management: Report/Proceedings