Assessment of Allelopathic Potentiality and Identification of Allelopathic Compounds on Korean Local Rice Varieties

This study was conducted to assess the allelopathic potentiality of Korea traditional seventy-nine rice (Oryza sativa L.) cultivars on barnyardgrass (Echinochloa crus-galli P. Beauv. var. oryzicola Ohwi) and to identify possible allelopathic compounds from selected rice cultivars, such as Seogandodobyeo, Huadobyeo and Heugbalbyeo. In the straw mixture, Seogandodobyeo showed the greatest inhibition (67.07%) on total emergence percentage. The greatest inhibition on total seedling length and dry weight of barnyardgrass occurred in Huadobyeo (58.32 %) and Heugbalbyeo (81.20%), respectively. An HPLC analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compound depend upon the cultivars. Four compounds including Ο-coumaric acid in Seogandodobyeo extracts, four compounds including p-coumaric acid in Huadobyeo extracts, and seven compounds including Ο-coumaric acid in Heugbalbyeo were detected, respectively. Ο-coumaric acid (0.97 mg/g) in Seogandodobyeo, p-coumaric acid (0.92mg/g) in Huadobyeo and Ο-coumaric acid (1.02 mg/g) in Heugbalbyeo was detected as the highest amounts, respectively. The preliminary identification by HPLC analysis resulted in peaks with retention times close to those of standards which were confirmed with EI/MS. The mass spectra of p-coumaric, and Ο-coumaric acids showed molecular ions (m/z) at 164 and 164, and their base peaks (m/z) at 164 and 118, respectively.