Allelopathic Effect of Powdered Russian Knapweed (Acroptilon repens L.) on the Growth Parameters of Redroot Amaranth (Amaranthus retroflexus L.)

To evaluate probable allelopathic effect of different parts of Russian knapweed (Acroptilon repens L.) on the growth of redroot amaranth (Amaranthus retroflexus L.) seedling, a factorial experiment was conducted based on randomized complete block design with three replications at the Faculty of Agriculture, Urmia University in 2012 (Iran). In this experiment, treatments were different parts of Russian knapweed (aerial part, flower and root) in different amounts (1, 2, 3 and 4 g/pot). Pots included 300 g of soil. Results showed the significant effect of Russian knapweed plant parts on the seedling emergence percent, root length, ratio of root/shoot length, seedling length, seedling fresh weight, and the significant effect of plant material amounts on the seedling emergence percent, seedling fresh weight and seedling dry weight. Interaction effect between plant material type and amount on the shoot length, root length, ratio of root/shoot length, seedling length was significant, too. The longest shoot (3.51 cm), root (1.75 cm), the highest ratio of root/shoot length (0.49) and seedling length (5.26 cm) belonged to control treatment. The highest seedling emergence percent of Amaranthus retroflexus (34.73%) and seedling fresh weight (0.176 g) were occurred at pots treated by Russian knapweed aerial part. The lowest seedling emergence percent (21.94 %) and seedling fresh weight (0.111 g) were obtained from application of Acroptilon repens powdered root. The maximum seedling dry (0.0126 g) and fresh (0.177 g) weight of Amaranthus retroflexus were obtained from control treatment.