Allelopathic potential of Cyperus rotundus L. I. Interference with crops

The root exudates of C. rotundus significantly reduced the root and shoot growth of tomato and cucumber plants, while, its residues incorporated at 3 and 6 g per kg soil inhibited the seedling growth of sorghum, soybean and cowpea and the reduction increased with the increased rates of residues. The volatile compounds released from its shoot and tubers significantly reduced the seedling growth of mungbean. In soil the toxicity of C. rotundus residues started 2- weeks after incorporation and continued for 8-weeks and then declined. Thus allelopathy was the causative factor for the reduction in growth of test crops by C. rotundus with competition probably accentuating its effect.