Investigation of allelopathic effects of umbrella sedge (Cyperus difformis L.) weed on germination and seedling stages of rice (Oryza sativa L.Tarommahalli)

Rice (Oryza sativa L.) is a member of Gramineae and umbrella sedge (Cyperus difformis L.) is one of the common weeds of the rice paddies. An experiment was set up in order to investigate the allelopathic effects of aqueous extracts obtained from root and shoot of umbrella sedge with 50% and 100% concentrations on seed germination and seedling stages of rice. The results showed that aqueous extracts reduced germination percentage, germination rate and total dry weight of rice compared with control (%72, 0.884seed/day and 0.322g respectively) and was significant (p≤0.05). At the seedling stage, the shoot length of the rice was reduced with all treatments and was not significant. Moreover, water content of seedling leaves was increased with all concentrations but with 50% root‘s extract (%50.90) compared with control (%53.07) was declined significant (p≤0.05). The fresh and dry weights of shoots increased in the all treatments in comparison with control (0.0764g and 0.0123g respectively) and difference were significant (p≤0.05). The fresh weight of root also increased with both extracts of root and shoot at 50% concentration but it was not significant. The results showed that seed germination stage of rice was significantly inhibited by all aqueous extracts of umbrella sedge (p≤0.05), but the aqueous extracts of umbrella sedge had different morphological and physiological effects on seedling stage that depended on organ type e.g. shoot length decline was not significant, but fresh and dry weights of shoot and water content of seedling leaves showed significant increase (p≤0.05) compared with control.