Wheat (Triticum aestivum L.) and groundnut (Arachis hypogaea L.) are important winter (Rabi) and summer (Kharif) crops of Pothwar region of the Punjab province of Pakistan. Yield of these crops is low due to various limiting factors especially uncontrolled weeds. Weed control through herbicides is posing serious threats to natural environment. It is needed to decrease dependence on herbicides for weed control and sustainable environment management. Allelopathic crops have potential to reduce herbicide usage in agro ecosystem. Field experiments were conducted at Research Farm of Pir Mehr Ali Shah Arid Agriculture University Chakwal Road Rawalpindi to determine effects of allelopathic crops water extracts and their combinations with herbicides on wheat and groundnut crops under rainfed conditions during 2009-2011. Nine weed control treatments were arranged in randomized complete block design with four replications. Weed control treatments reduced total weeds density, fresh and dry weights of weeds during both years in wheat crop. Amongst treatments, allelopathic crops [Sorghum (Sorghum bicolor L.) and sunflower (Helianthus annuus L.)] water extracts alone and their mixture reduced total weeds density, fresh and dry weights by 30, 31 and 32%, respectively. Herbicide [Atlantis® 3.60 WG (mesosulfuron + iodosulfuron)] at recommended dose (14.4 g a.i. ha-1) and combinations of sorghum and sunflower water extracts with its lower rates (3.6, 7.2 and 10.8 g a.i. ha-1) reduced weeds dynamics between 66 to 70%. Hand weeding reduced weeds to higher extent (84-87%) but it was labour intensive and costly method. xxv Higher values of leaf area, leaf area index, total dry matter accumulation, crop growth rate, net assimilation rate and relative growth rate were recorded from combination of sorghum and sunflower water extract with Atlantis® @ 10.8 g a.i. ha-1 (75% of full dose) and Atlantis® @ 14.4 g a.i. ha-1 (full dose). These treatments also produced more number of fertile tillers per unit area, grains per spike and grains yield. Crop extracts mixed with 75% dose of herbicide improved wheat grain yields upto 46% which was comparable with herbicide at full dose and hand weeding. The maximum protein (15.32%) and starch contents (54.22%) were recorded from weedy check and hand weeding, respectively. Economic and marginal analyses revealed that crop extracts mixed with 75% rates of herbicide exhibited the highest net benefits. Allelopathic extracts mixed with lower rates of Atlantis® gave higher marginal rate of return (423-532%) while other treatments were dominated due to lower marginal net benefits. Different weed control treatments decreased weeds dynamics in groundnut during both seasons. Herbicide application at full rates (Haloxyfop 10.8 EC @ 108 g a.i. ha-1), allelopathic crops extracts [Barley (Hordeum vulgare L.) and brassica (Brassica campestris L.)] and their mixtures with reduced doses of haloxyfop decreased total weeds density in the range of 33-38%, 1-16% and 18-39%, total weeds fresh weight between 12-25%, 5-19% and 14-36% and total weeds dry weights ranging 13-26%, 6-20% and 14-38%, respectively. Combination of 75% dose of herbicide with allelopathic crops extracts reduced total weeds density, total weeds fresh and dry weights by 39, 36 and 38%, respectively. Although hand weeding controlled weeds biomass by 74% but it was a costly approach. xxvi Barley and brassica extracts combined with haloxyfop @ 81 g a.i. ha-1 (75% of full dose), full dose of haloxyfop (108 g a.i. ha-1) and hand weeding enhanced leaf area, leaf area index, total dry matter accumulation, number of pods per plant, kernels per pod and pods yield. The maximum pods yield was recorded from hand weeding (1526 kg ha-1) followed by crop extracts mixed with 75% dose of herbicide (1409 kg ha-1). Oil contents were not affected significantly by different weed control treatments. Economic and marginal analyses showed higher net returns from lower herbicide doses combined with allelopathic crops water extracts. These treatments gave 37-943% marginal rate of return while all other treatments including hand weeding were dominated due to less net benefits. The study concluded that allelopathic crop water extracts mixed with low rates of herbicides (50-75% rates of full herbicide dose) can be used for economical weed control and improvement of wheat and groundnut yields.