Root exudates, along with dead root hairs, epidermal cells, and root caps, are a source of energy for the microbial community in the rhizoplane and rhizosphere. They aid in the mineralization of organic matter, nutrient cycling, and trace gas (CH4, N2O, etc.) production (Aulakh et al 2001). MacRae and Castro (1966), Marathe (1970), and Waschutza et al (1992) have identified raffinose, glucose, fructose, arabinose, ribose, and xylose in rice exudates. Glucose is the most abundant of all sugar exudates of plants in general (Boureau 1977). With growth of rice, the exudation of organic acids such as oxalic, succinic, aconitic, citric, malic, tartaric, and lactic acids substitutes for the exudation of sugars (Aulakh et al 2001, Boureau 1977). Root and shoot biomass was positively correlated with carbon exudation, suggesting that it is driven by plant biomass (Aulakh et al 2001). A decrease in exudation was observed by Vancura et al (1977) when the source of seedling nutrition shifted from stored substances in the seeds and the endosperm to photosynthesizing leaves. As the nutrient supply from the leaves increases, root exudation increases again and maintains a rising trend up to the time of flowering.