Abstract
This study was conducted in the glasshouse in Biology Department \ College of Science\ Mosul University to study the effect of the crops (wheat, Barley, corn ,Sun flower) residues added to the soil at ratio (5%) W:W in seed germination and growth of four weeds includes (Silybum marianum L ., Lolium rigidum L., Sonchus oleraceus L., Panicum Spp.). The result showed inhibition in seed germination and growth of the weeds growing in the soil containing the crops residues compared with the plant (weeds) growing in control soil (without residues) showing significant difference between crop residues rather than weed species (using a multi-range Duncan test at a 5%) . It was found that the greatest inhibition in seed germination and shoot length of Silybum marianum L. effect by Wheat residues reaching 36.05% , 24.49% , respectively which was accompanied with reeducation in these stem diameter section 28.6% .in root growth was found that the greatest inhibition recorded 42.85% in Lolium rigidum L. that growth in soil content barley residues also Wheat residues caused the greatest inhibition root diameter section in sonchus oleraceus L. 59.13% ,While remarked increases in vascular calendar diameter for Lolium rigidum L. effect by corn residues accompanied increases in root length , that the greatest inhibition in leaf area of Lolium rigidum L. 83.27% effect by corn residues accompanied inhibition wider cell epidermis 62.88% ,in dry weight of Silybum marianum L. show the greatest inhibition effect by sunflower residues 70.46% .
