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The Scientific World Journal
Volume 2012 (2012), Article ID 603043, 10 pages
Research Article

Critical Period of Weed Control in Aerobic Rice

1Institute of Tropical Agriculture, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
2Department of Agronomy, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
3Department of Crop Science, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
4Rice and Industrial Crops Research Centre, Malaysian Agricultural Research and Development Institute, Kuala Lumpur 50774, Malaysia

Received 7 March 2012; Accepted 14 April 2012

Academic Editors: C. Dell, H. A. Torbert, and M. Tsubo

Copyright © 2012 M. P. Anwar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return.