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INTRODUCTION
Crop plants suffers stress caused by unwanted weeds through competition for water, light nutrients and space. Stress created by weed plants results in an increasing mortality of whole crop plant, reduced growth, decreases in output and quality (Gallandt and Weiner, 2001). Reduction in wheat yield from 20 - 60% due to weed infestations (Turk and Tawaha, 2002). Loses in different crops due to weeds infestation in Pakistan are 20 to 30%. In cereal crops, the losses due to weed infestations are approximately 30, 40, 4 and 5 billion rupees for wheat, rice, gram and maize, respectively (Anonymous, 2005).Therefore, it is necessary to control the weeds before critical competition period to enhance the yield of crop (Macias et al., 2002).
Different methods are used to control weeds such as biological, chemical, mechanical, and cultural weed control (Melander et al., 2005). In modern agriculture production system weeds efficiently controlled by use of chemical herbicides (Bajwa, 2014). The use of chemical for effective weed control result in low quality of product, weed resistance, environmental pollution (Macias et al., 2002). Extreme and continuous application of same type of herbicides has resulted in resilient weed populations and this phenomenon urged upon the misuse of allelopathic possible of crop plants (Ferreira and Reinhardt, 2010). Allelochemicals could be used as tool to control weeds and resistance (Jabranet al., 2015). Allelopathic plants have ability to inhibit the initial weeds growth (Chung et al., 2006).
Opium (P. somniferum) a common medicinal plant, belonging to family Papaveraceae. (Labancaet et al., 2018). Many researchers reported that opium crop release different allelochemicals at maturity which inhibit growth of various plants including crops and weeds. According to Alam and Islam (2002) water extract of some weeds might have promotry or inhibitory effect on germination and initial seedling growth of target weed. Different plants have different potential on target weed or crop plant.Water extract of wild onion leaves produced inhibitory impact on wheat crop germination and initial growth of seedling (Baber et al., 2009).
Opium is most important dominant and competitive broad-leaves weed in winter cereals reported to have allelopathic effect, the water extracts from fresh plant parts of opium significantly inhibit germination of both barley and wheat crop (Ravlicet al., 2012). Ghodake et al., (2012) reported that...