Fifty-four Korean native and 28 foreign rice varieties harvested in 1998 and 1999 were examined for antioxidative activity that is measured to a chemiluminescence and superoxide radical intensity, by the flow injection chemiluminescence (FI-CL) system and an electron spin resonance (ESR) spectrophotometer, respectively. In the chemiluminescence measurement by FI-CL, radical scavenger activity did not differ significantly among rice varieties between origin types of rice varieties, and between storage periods. GinSun and Hongchoengdo, colored rice exhibited high electron scavenging effect by ESR. Therefore, these results indicate that the pigments of rice varieties may play important antioxidative roles and that it may be possible to breed rice varieties with higher antioxidative potentials.

Fifty-four Korean native and 28 foreign varieties harvested in 1998 and 1999 were examined for superoxide dismutase (SOD) and peroxidase (POD) activities. The SOD and POD activities of leaves extracts in Korean native and foreign rice varieties showed variation at the heading stage. The activities of SOD and POD changed with growth stage. In comparison of storage duration, the SOD and POD activities of the extract from three months stored seeds in Korean native (CV=53.3%) and foreign rice (CV=57.9%) varieties were higher than that of stored rices for a year in seed extracts although the activities among varieties did not show significant variation. Also, the averaged activity of foreign rice varieties (SOD=12.9%) was relatively higher than that of korean native rice varieties (SOD=10.7%). The test of activity at the enzymatic level related to antioxidative activity suggests that the rice varieties with higher antioxidative potentials can be developed and also may provide information with rice breeder to breed rice variety with a high antioxidative activity

This study was to investigate antioxidative activity of rice grain using 1, 1-Diphenyl-2-picrylhydrazyl(DPPH) and thiobarbituric acid (TBA) method and germination ability for screening rice varieties with high antioxidative activities on korean native and foreign rice varieties harvested in 1998 and 1999. The average antioxidative activity of foreign rice varieties (DPPH 63.5% and TBA 55.2%) was significantly higher than that of native rice varieties (DPPH 47.2% and TBA 45.6%) on varieties harvested in 1999. The promptness index (PI) of native rice varieties was higher in stored rices for three months (mean PI=160.7) than that of stored rices for a year (mean PI=141.6). On the other hand, the PI of foreign rice varieties was higher in stored rices stored for a year (mean PI=176.7) than that of stored rices for three months (mean PI=157.5). Varieties with high redness of hulled rice (a-value) showed significant lipid peroxidation inhibitory activity to DPPH in a stored rices for a year (r=0.5744** ) and stored rices for three months (r=0.5630** ) . These results indicate that the pigments of hulled rice varieties may play important antioxidative roles and colored rice varieties with higher antioxidative potentials can be developed and also may provide information with rice breeder to breed rice variety with a high antioxidative activity for a rapid screening of a small amounts of a large number of samples using color value.

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.

본 실험은 포장에서 주로 발생하는 velvetleaf등을 비롯하여 7종류의 잡초를 마른 상태와 생체상태로 각각 수확하여 지상부와 지하부로 나누어 물질을 추출 이들을 alfalfa 종자 발아와 생육정도 검정에 사용하여 지상부와 지하부의 생육억제정도를 비교하였으며 이 중 억제효과가 제일 큰 velvet-leaf의 추출물은 여러 농도로 silica sand와 혼합하여 alfalfa에 대한 타감작용을 검토하였다. 1. 7종류 잡초의 지상부와 지하부의 추출물 처리는 alfalfa의 발아율, 발아세, 유근의 길이, 무게 등을 억제시켰다. 지상부와 지하부의 억제효과를 비교하면 지상부의 추출물이 지하부의 추출물 보다 더 큰 타감작용을 보였으며, 이 중에서 velvetleaf 추출물이 가장 억제적이었고, crab-grass 추출물은 가장 낮은 억제 정도를 보였다. 또 alfalfa 발아와 유근의 생육에 대한 velvetleaf의 건조 추출물과 생체 추출물을 비교하면 건조 추출물이 더 억제적이었다. 2. 농도에 따르는 velvetleaf 추출물 처리에서는 농도가 증가할수록 alfalfa 발아율, 유근의 길이, 무게 등이 대조구와 비교하여 상대적으로 더 억제되었다. 3. 건조된 velvetleaf 잔기를 silica sand와 혼합처리에서 잔기의 비율이 증가 될수록 alfalfa의 출현율과 생존율이 더 억제되었으며 그 정도는 잔기 비율 1%에서 가장 억제적이었다. 4. 잡초의 추출물과 잔기의 처리는 alfalfa의 발아와 생육에 억제적으로 작용 하여 타감작용이 인정되었다.