Allelopathic Effect of Plantago psyllium on Germination and Growth Stages of Four Weed Species

Field observations suggested that French psyllium (Plantago psyllium) probably exerts allelopathic effects, although there was no evidence in the literature to support this assumption. The main objectives of this study were to determine whether P. psyllium affects the germination and growth of some weeds by allelopathic function. To explore allelopathic responses of P. psyllium upon germination and growth stages of redroot pigweed (Amaranthus retroflexus ), wild barley (Hordeum leporinum), black mustard (Brassica nigra), Lambsquarters (Chenopodioum album L.), a laboratory bioassay and three greenhouse experiments including root and above ground residues of P. psyllium effects and simultaneous growth of P. psyllium with weeds on target plants were conducted. Results showed that aqueous shoot extract, shoot residue and simultaneous growth of P. psyllium displayed the most consistent negative effects on germination and dry matter of target plants, respectively. Shoot residue and simultaneous growth significantly decreased height and dry matter of all target species except for wild barley. On the other hand, there were no significant effects of root residue of Corresponence to: Asghar Rahimi, Rahimiasg@yahoo.com A.Rahimi et al 14 P.psyllium on dry matter and height of target plants. Results also showed that P. psyllium can decrease the ability of weeds to germinate, grow and survive especially in drought-prone environments and where water resources are limited.