A Ready Reckoner for Rice Weeds

Abstract

Rice (Oryza sativa) is the staple food of Southeast Asian population. Rice is the source of livelihood for hundreds of millions of house holds around the Globe. Several Asian and African countries are highly dependent on rice as a source of food and foreign exchange and government revenue (www.fao.org). Global rice production must increase by 36% by 2025 to feed an estimated 4 billion rice consumers (Pinstrup Anderson et al., 1997). Water scarcity prevails in rice growing areas (Tuong et al., 2005) and societal demands for water from the urban and commercial sectors will continue to increase. In response to rising production costs; especially for labor and water resources, farmers are shifting the methods of crop establishment from traditional transplanting to direct seeding. But direct seeding of rice faces severe challenges from weeds which are a major deterrent in increasing the rice production and productivity. Integrating preventive and interventional methods are essential to manage the weed communities. (Raoet. al., 2007) and improved weed management will be quite crucial. Over 1800 plant species have been reported as weeds of rice in South and South east Asia (Moody 1989) and there is an enormous diversity of taxa considered to be weeds of rice (Soerjani et. al., 1987) Since rice is grown over a wide range of agro ecosystems, such as flooded fully or partially (irrigated) uplands which are highly prove for weed Infestation. In many developing countries, rice farming relies on manual labour and weed control is inefficient leading to their persistence. Weeds compete with the rice plants for nutrients, moisture, sunlight and space, causing a quantitative reduction in the potential yield of rice.