Laboratory and field experiments were conducted to study interference and weed control in direct-seeded rice. The effect of root, shoot, leaf, seed and whole plant water extracts of Trianthema portulacastrum, Dactyloctenium aegyptium and Eleusine indica on germination and seedling growth of rice was studied in Petri dish bioassays. The seed germination was recorded daily for sixteen days. Rice seeds were also sown in sand culture to assess the seedling growth of rice with same water extracts. The maximum reduction in rice germination was observed with leaf extract of T. portulacastrum. Significantly lower root and shoot length of rice seedlings was observed where rice seeds were treated with water extracts of leaf and whole plant of T. portulacastrum. Germination and early growth of rice was affected the most by application of leaf extract of T. portulacastrum to rice before sowing compared with extracts of other weeds. A laboratory experiment was also conducted to evaluate the allelopathic effects of water extracts of sunflower and sorghum alone and in combination on the germination and early growth of rice and weeds viz: Trianthema portulacastrum, Dactyloctenium aegyptium and Eleusine indica. Sunflower and sorghum water extracts when applied in combination caused the maximum inhibitory effects on germination of E. indica and T. portulacastrum than when applied separately. Sorghum water extract caused maximum reduction in germination percentage of seeds of T. portulacastrum. Whereas, sunflower water extract caused maximum inhibitory effects on mean germination time of D. aegyptium seeds. Water extracts of sorghum, sunflower when applied alone and in combination increased the root, shoot length and the seedling biomass of rice over control. Combined application of sorghum and sunflower water extracts resulted in greatest root length reduction in T. portulacastrum. It was concluded that the combined application of sorghum and sunflower water extracts is overall more inhibitory to the germination of rice, T. portulacastrum, D. aegyptium and E. indica than when applied separately. However, the sorghum and sunflower mixture promoted the seedling growth of rice. Two field experiments were conducted to determine the most suitable sowing time, the critical period of weed-crop competition, and most effective methods of controlling weeds in direct-seeded rice. These experiments were laid out in a randomized complete block