Allelopatic Effect of Bermudagrass (Cynodon dactylon L.) Extract and Residues onWheat (Triticumaestivum L.)

With regards to the importance and frequency of bermuda-grass (Cynodon dactylon L.) in wheat fields an experiment was conducted using factorial design in three replicates to evaluate allelopathic effects of different parts extract and residues of bermuda-grass in different concentrations on wh eat germination and yield in 2008. Five levels of organ extracts as control, leaf, shoot, root and intact plant extract of bermuda-grass in four concentrations as 20, 10, 7, and 5 % were used. All extracts decreased germination and its components in wheat. The highest decreasing effect was belonged to the root and intact plant extract. In glasshouse, increasing extract concentration from 5 to 20% decreased all attributes significantly. Decrease in seed number per plant, 100-kernel weight and yield in 20% was 89, 769 and 96% less than control, respectively. Field trial confirmed glasshouse results. Generally, root and intact plant extract and residual had higher growth restriction than shoot and leaf residuals and extract on wheat attributes. In field condition, applying bermuda-grass extract decreased 71% and residual 81% of wheat yield. It may be depends on gradual leaching of allelochemicals from residuals of bermuda-grass in growth period that affect growth and yield of wheat.