Health beneficial properties of soybean [Glycine max (L.) Merr.] isoflavones are well known. The objectives of this study were to determine and compare the isoflavone composition and concentrations of soybean varieties grown in different cultivated regions of Vietnam (i.e., upland and lowland). Total and individual isoflavone composition and concentrations were determined by high-performance liquid chromatography (HPLC). Total isoflavone concentrations varied from 1153 to 6604~mug~;g-1 and averaging 3354~mug~;g-1 across environments and varieties. In the lowland region, the highest total isoflavones concentration was observed in M103 cultivar (5653~mug~;g-1 ) and the lowest in VX9-3 (1153~mug~;g-1 ), whereas in the upland region the highest and lowest concentrations were in M103 (6604~mug~;g-1 ) and DT93 (1938~mug~;g-1 ), respectively. Across varieties, average total isoflavones concentration was higher in the upland than lowland region (3728 vs. 2980~mug~;g-1 ). The malonylglucosides and acetylglucosides concentrations in upland soybean varieties were higher than those from the lowland region. Despite the presence of Genotype (G) x Environment (E) interactions, varieties with consistently high (M103) and low (VX9-3, DT93) isoflavone concentrations across environments were identified. This is the first report of isoflavones in Vietnamese soybean varieties, revealing large variation in isoflavones concentration and profile among different varieties and cultivated regions. Results will be useful in selecting high-isoflavones soybean varieties for growth in tropical regions.

The objective of this study was to determine the role of storing years with the variation of total phenol and individual phenolic compounds in soybean (Glycine max L.) seeds. The total phenol content varied from 0.36 to 0.42% over four years, with the highest value (0.42%) found at storage for two and three years. Among the nine soybean varieties examined, Daweonkong had the highest total average phenol content (0.58%). The total content of 11 phenolics varied from 730.0 to 1812.8 ~mu~textrmg~;~textrmg-1 over storage for four years, and the highest concentration (1812.8 ~mu~textrmg~;~textrmg-1 ) was found at storage for two years. Myeongjunamulkong (1465.4 ~mu~textrmg~;~textrmg-1 ) had the highest mean content among the nine soybean varieties. The total content of 11 phenolic compounds measured in this study occupied from 20.96 to 47.73% of the total phenol contents. The highest total phenol contents were in seeds with black coats (5279.4 ~mu~textrmg~;~textrmg-1 ), while the highest concentration of individual phenolic compounds were in seeds with green coats (1419.5 ~mu~textrmg~;~textrmg-1 ). Our study suggests that it may be feasible to improve soybean varieties with high functional substances such as phenolic compounds.

Effects of ambient and elevated ~textrmCO2 and high temperature, and their interactions with zero and applied nitrogen supply (NN-no nitrogen and AN-applied nitrogen) were studied on soybean (Glycine max L.) in 2001. In this experiment, elevated ~textrmCO2 (650 ~mu~textrmmol.~textrmmol-1 ) and temperature (+5~circ ) increased total dry mass at final harvest by 125% and 119% and seed weight per plant by 57% and 105% for NN and AN plants, respectively. Although the influence of temperature and temperature x ~textrmCO2 were not significant, the influences of ~textrmCO2 concentration and temperature x ~textrmCO2 concentration were significant on total dry weight and seed weight, respectively. In particular, seed weight per plant was increased, while weight per one hundred seed weight was decreased with elevated ~textrmCO2 and temperature. The N supply increased biomass and seed weight per soybean plants. The results of this study suggest that the long-term adaptation of soybean growth at an elevated ~textrmCO2 concentration and high temperature might potentially result in a increase in dry matter production and yield.

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.

Sixty local soybean cultivars were evaluated on the antioxidative activity by superoxide dismutase (SOD), 1, 1-diphenyl-2-picrylhydrazyl (DPPH), thiobarbituric acid(TBA), and chemiluminescence using the FI-CL system. Soybean were collected throughout the country, and were grown over two years (1997 and 1998) for measuring antioxidative activity in soybean seeds. There were differences in antioxidative activity depen-ding on the method of measurement and variation of the crop year. Soybeans from Kwangyang-shi-1 (76.78%) in 1997 and Kangjin-gun-3(79.14%) in 1998 showed the highest SOD activity, whereas those from Hwasoon-gun (80.43%) in 1997 and Kangjin-gun-2 (49.82 %) in 1998 exhibited the highest DPPH activity. Soybeans from Chongup-gun-2 (75.77%) in 1997 and from Yochon-shi-5 (69.17%) in 1998 exhibited the highest TBA activity, and those from Jinahn-gun (48.99%) in 1997 and Kohung-gun (49.73%) in 1998 exhibited the highest activity using the chemiluminescence method. These results suggest that it may be possible to develop soybean varieties with higher antioxidative activity

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 experiment was designed to assess changes in yield difference between waxy (IWR) and non-waxy (INWR) near isogenic rice by evaluating the translocation and accumulation of assimilates in different parts of the rice plants after heading stage under different fertilizer application. Nitrogen content of culm in both IWR and INWR decreased rapidly from 35 days before heading to flowering time and after then it was maintained constantly, while the nitrogen content of leaf blade was continually reduced. Sugar content of leaf blade in IWR decreased steadly by 10 days after heading, but that in INWR increased 20 days after heading. There was no difference in starch content of culum between IWR and INWR from 35days before heading to heading, but that of culm of IWR increased again after heading. Dry weight of IWR plant was less reduced during ripening as compared with INWR. The dry weight of culm was not significantly different between two isogenic lines.