An Overview of Weeds and Weed Management in Rice of South Asia

Rao, A N and Wani, S P and Ahmed, S and Haider Ali, H and Marambe, B (2017) An Overview of Weeds and Weed Management in Rice of South Asia. In: Weed management in rice in the Asian-Pacific region. Asian-Pacific Weed Science Society (APWSS), Hyderabad, pp. 247-281. ISBN 978-81-931978-4-4

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South Asia produces slightly above 225 million tons of rice (30.7% of global production) on 60 million hectares (37.6% of the global area). India and Bangladesh are the major rice-growing countries. India contributes around a quarter of global production from 43 million hectares (the largest rice cultivating area). In South Asia, manually transplanting rice seedlings into flooded soil (TPR) is the common method of rice establishment. But direct-seeded rice (DSR) is gaining importance due to shortage and increased cost of resources. In Sri Lanka 93% of rice is cultivated as wet-seeded rice. However, the weeds are major constraints in DSR causing higher (14 to 100%) than in TPR (7 to 80%). Major rice weeds in South Asia include: Echinochloa crus-galli (L.) P. Beauv., Echinochloa colona (L.) Link., Cyperus rotundus L., Cyperus iria Linn., Cyperus difformis L., red rice (Oryza sativa L.), Leptochloa chinensis (L.) Nees, Ischaemum rugosum Salisb., Paspalum distichum L., Dactyloctenium aegyptium (L.) Willd., Cynodon dactylon (L.) Pers., Echinochloa crus-galli (L.) P. Beauv., Eleusine indica (L.) Pers., and Fimbristylis miliacea (L.) Vahl. Weeds flora was reported to vary with location, method of rice establishment, cultural practices used and associated environment. The small-holders’ traditional weed control method is hand weeding by hand-held hoe and hand pulling. Hand weeding is still a major method of weed control. However, the herbicide use is increasing due to non-availability and increased cost of labour in several of the South Asian countries. Mechanical weeders are being used by farmers as they reduce labor use and cost of weeding (72 to 74%). Tillage, mulching, crop rotation, allelopathic competitive crop cultivars, intercropping, balanced nutrient and water management and preventive measures have proven to be effective as a component of integrated weed management in rice of South Asian countries. Herbicide resistance among weeds in rice was not reported in India, Bangladesh, Nepal and Pakistan. Herbicide resistant biotypes of E. crus-galli, I. rugosum and C. iria were reported in Sri Lanka. In South Asia, herbicide tolerant rice is yet to be made available to farming community. Weed management research must be focused on identifying location specific effective, environment friendly, economically viable integrated weed management strategies.

Item Type: Book Section
Divisions: Research Program : Asia
Uncontrolled Keywords: South Asia, rice, weed management, herbicides, herbicide resistant weeds, herbicide tolerant rice
Subjects: Others > Cereals
Others > Rice
Others > Weed Science
Others > Asia
Depositing User: Mr Ramesh K
Date Deposited: 16 Oct 2017 09:04
Last Modified: 16 Oct 2017 09:05
Acknowledgement: A.N. Rao extends his thanks to Government of Karnataka, India, (Bhoosamrudhi); Government of Andhra Pradesh, India; IRRI and ICRISAT for financial support.
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