Growth inhibitory effects of nutgrass (Cyperus rotundus) on rice (Oryza sativa) seedlings

Growth inhibitory effects of aqueous extracts and leachates of leaves and t ubers of Cyperus rotundus L. were investigated by using rice (Oryza sativa L.) seedling as a bioassay material. Both the extracts and leachates of Cyp erus were inhibitory to the growth of rice seedlings. Growth inhibition was more pronounced in the presence of aqueous extracts than the leachates. Th e extract and leachate of leaves had higher total phenolic contents than th ose of the tubers. Soil amendment with fresh leaves of Cyperus reduced plan t height, leaf area, and root and shoot weight of rice seedlings. Total phe nolic content was higher in soil amended with fresh Cyperus leaves than the unamended control soil. Nineteen compounds were tentatively identified fro m the aqueous extracts of leaves and tubers by ethyl acetate extraction fol lowed by gas chromatography-mass spectroscopy (GC-MS). Dicarboxylic, phenol ic, and fatty acids were the major compounds. Our results suggest that Cype rus may affect the growth and establishment of rice seedlings after sowing or transplanting, especially when Cyperus plants are mixed in soil during l and preparation by ploughing in rain-fed rice culture.