Weed Management in Direct‐Seeded Rice
Section snippets
INTRODUCTION
Over 1800 plant species have been reported as weeds of rice in South and Southeast Asia (Moody, 1989), and there is an enormous diversity of taxa considered to be weeds of rice (Soerjani et al., 1987). There are two major reasons for this. The first is that rice is grown over a range of agroecosystems, characterized by the presence or absence of water (from dry land to fully flooded land) for all or parts of its growing season, which generates highly diverse weed floras. The second is that, in
OCCURRENCE OF MAJOR WEEDS IN DIFFERENT METHODS OF DIRECT‐SEEDING ACROSS THE WORLD
Globally, weed communities of DSR are floristically diverse because they (1) span temperate and tropical regions, (2) reflect different agroecosystems in a region, (3) may vary in relation to seasonal crop management patterns at the farm level, and (4) may differ because of spatial heterogeneity that is often linked to patterns of flooding and drainage and soil nutrition at the field level (Moody 1995, Mortimer and Johnson, 2005). They can vary further in relation to the efficacy of weed
INTEGRATING WEED MANAGEMENT PRACTICES IN DIRECT‐SEEDED RICE
The traditional practice of puddling soil to kill existing weeds and aid water retention, transplanting rice seedlings into standing water to achieve an optimum stand density, and maintaining standing water to suppress weeds, followed by one or several periods of manual weeding, is a well‐established example of integrated weed management (IWM). It is integrated in the sense that it involves preventive actions followed by precise interventions as a response to the consequences of suites of
FUTURE RESEARCH NEEDS
Weed infestation is a major threat to yield and further expansion of DSR throughout the world. In most developed nations, direct‐seeding is the sole method of rice establishment and is reliant on mechanization and close attention to weed management. While shortage of labor in Asian agriculture is encouraging the adoption of direct‐seeding, so too is the need to improve water productivity (Tuong et al., 2005). “Aerobic” rice (Bouman, 2003) may reduce water consumption by up to 50% (Yang
ACKNOWLEDGMENTS
The authors are grateful to Cropnosis Limited for providing data on herbicide sales; Drs. Y. Singh, M. M. Kyu, H. Pane, and A. Abeysekera for their advice on the distribution of weed species; Professor Robert E. L. Naylor, University of Aberdeen, UK; Drs. N. T. Yaduraju and H. Pathak, Indian Agricultural Research Institute, India for providing critical and constructive comments on the chapter; and Dr. Bill Hardy, Senior editor, IRRI for editing the chapter.
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