This study was carried out to investigate the proper interval of water exchange according to nitrogen fertilizer level at medium saline soil which are 0.3 or more soil salinity in southwestern reclaimed saline land. The nitrogen fertilizer level were 14, 17, 20kg per 10a, and the interval of water exchange were every 3, 6, 9 days after transplanting. The summarized experimental results are as follows. The salinity were maintained as low when the interval of water exchange were every 3 or 6 days after transplanting, but salinity was highest at rooting stage, and decreased from that, so salinity were about 0.3 at panicle initiation stage or ripening stage when the interval of water exchange was every 9 days after transplanting. The rice yield were 537-552kg/10a when the interval of water exchange was every 3 days with 17-20kg/10a nitrogen fertilizer level, and 519-533kg/10a when the interval of water exchange was every 6 days with 17-20kg/10a nitrogen fertilizer level, but decreased outstandingly in the other treatments. Considering the yield and salt injury at medium saline soil at southwestern reclaimed saline land, proper nitrogen fertilizer level was 17-20kg/10a when the interval of water exchange were every 3 or 6 days after transplanting.

Acid rain due to air pollution has been believed to be harmful to vegetation and crops, either by direct deposition on the foliage or by indirect leaching of nutrients from the soil. This study was conducted to investigate physiological response and damage of soybean caused by acid rain in the glasshouse at the experimental station of Seoul National University. Soybean (Glycine max L.) cv. Sinpaldal was subjected to simulated acid rain (SAR) two times a week from R2 stage until its maturity. The pH values of SAR treatments were ranged from 2 to 5 together with tap water treatment (pH 7±0.2) as a control. The SAR was composed of H2SO4 and HNO3 at the ratio of 2:1 (v/v). SAR treatment at pH 2 caused clear visual damage on leaves and pods with severe chlorosis and necrosis even after the first SAR was applied, while those at pH greater than 3 showed no clear visual damage. Chlorophyll content (expressed as SPAD value) tended to decrease with decreasing pH with significant reduction at pH 2 as compared with pH values greater than 3. Photosynthesis also showed decrease with decreasing pH with significant reduction at pH 3 and 2. Soybean yield and its components were also affected by SAR treatment, particularly significant at pH 2.

A complete diallel cross was performed to determine the inheritance of allelopathic potential and combining ability of six rice germplasm that showed different level of allelopathic potential against barnyardgrass. Parents and F1 of 30 crosses were assessed for allelophatic potential in field condition. Barnyardgrass (Echinochloa crus-galli (L.) Beauv. var. frumentaceae) was used for rice allelopathic potential indicator which was observed in height and shoot dry weight, then suppression percentage were calculated by comparing to barnyardgrass grown in control plot (no rice). It was found that general combining ability showed no significant effect, whereas specific combining ability and reciprocal effect were significant. Variance analysis confirmed that genetic control of allelopathic potential in rice against barnyardgrass was mostly directed by dominance gene effect. The dominant genes were associated with high allelopathic potential and recessive genes were associated with low allelopathic potential. Heritability in broad sense for barnyardgrass dry weight suppression was around 41%; whereas for barnyardgrass height suppression was 51%. However, heritability in narrow sense was very low. The finding suggests that accumulation of genes associated with allelopathic potential would be a strategy to develop promising varieties in reference with the specific combining ability of cross combinations.

복부 단순방사선 촬영은 흉부촬영에 이어 가장 많이 검사가 이루어지고 있는 실정인 것이 임상현장 이므로 환자의 피폭선량에 대한 연구가 필수적으로 진행이 이루어 질 필요성이 대두가 된다. 그 결과는 다음과 같았다. 1. 관전압이 60-85kV 증가 시 표면선량은 증가하고, 촬영거리를 50-150cm로 20cm씩 증가함에 mAs도 증가시킨 결과 표면선량은 감소되었다. 2. 심부선량 백분율은 60-75kV에서는 4cm 깊이, 80-85kV에서는 6cm 깊이에서 50% 이하를 나타 내었으며, 60kV에서는 12cm 깊이, 65-85kV에서는 14cm 깊이에서 5% 이하를 나타났다. 3. 전방산란율은 60-85kV까지 관전압이 증가 시 10-11.78%까지 증가함을 나타내었다. 후방 산란 율은 관전압이 60-85kV 증가 시 25-37%로 증가하였다. 측방산란율은 음극 측에서는 관전압이 60-85kV 증가 시 1.63-2.95%로 완만하게 증가하나 양극측은 그 반대로 감소하는데 그 원인은 heel effect 현상 때문인가 사료된다. 후방산란율이 가장 크고, 그 다음이 전방산란율, 측방산란율 순으로 작아짐을 알 수 있다.