Tea plants growing under natural condition meet various stresses. The tea plants often subjected to adverse condition like low temperature and high light intensity during overwintering. Because tea plant is adapted well to low light intensity, higher light intensity might induce negative effects on tea growth at open field (exposed habitat). We investigated tea plant planted with the seeds of wild tea trees growing at Unsu-ri, Hwagaemyun, Hadong-gun on Nov. in 2008. The experimental field for juvenile tea plants was located in the hill neighboring GSNU at Jinju, Korea. We divided the field into open, semi-shaded, and shaded condition. Light intensity (PAR) at open condition was two times and twenty times higher than at semi-shaded and shaded condition, respectively. Growth of tea plants was highly dependent on light condition, the plants at open field was extremely poor as compared to plants grown at shaded field. Height of plants at open, semi-shaded, and shaded field were 14, 17.3, and 17.8 cm, respectively. Leaf size was also greater in plants grown at shaded field. Photosynthesis-related chlorophyll fluorescence (quantum yield) was also higher in shaded plants. Fv/Fm value of plants grown at open fields was lower by 50% as compared to that of the plants grown at shaded field. Chlorophyll content measured by SPAD meter also indicated higher value in open field plant than shaded plants. Our results suggested the photoinhibition during overwintering period strongly affects the growth juvenile tea plants because there was no significant difference in soil moisture content between open and shaded condition.

Chinese milk vetch (CMV) is a winter legume that is commonly used as cover crop in Korea. Kill date of cover crop for addition into soil affects N content in cover crop and N availability in soil. This study was conducted to evaluate the effect of CMV as green manure cover crop according to kill dates before growing corn without artificial fertilizer. Top of CMV cut three times on 13 April, 27 April, and 11 May were added into soil at a rate of 600 kg per 10a. Sugar content in CMV litter was persistently decreased from mid-April to late-May. The decrease of sugar content might be due to the transformation into starch and/or other storage or structural constituents. The decreased amount of sugars was greater than 12% and the increased amount of starch was less than 0.2%. Concentration of NH4+ in soil treated by CMV litter cut on May 11 was slightly higher than that in the treatment with early-cut (April 13) CMV, the concentration at 28 and 49 DAT (days after treatment) was higher in the treatment with late-cut CMV litter. Regardless of cut (kill) date of CMV, the phosphatase activity in the treatment of CMV litter was higher compared to the untreated control. Soil dehydrogenase activity was increased steadily by addition of CMV litter implying total microbial activities in the soil were increased. Our results demonstrate that the status of cover crop species at kill date is an important factor influencing soil enzyme activities derived from microorganisms. Therefore, the optimal kill date of cover crop should be examined to improve the efficiency of cover crop as green manure crop regarding the practical sequence in cropping system

Soybean quality is determined based on protein content, lipid content and fatty acid composition, and several functional components including isoflavones, anthocyanins and functional activity. Because the level of each component changes during seed development, it is necessary to know the concentration of quality-related components in developing seeds. Little is known of the pattern of changes in quality-related components. Seeds from field-grown soybean was harvest from the R6 stage to the R8 stage in 2004. Seed characteristics and the level of nutritional components were examined. Seed moisture content was dropped rapidly after the R7 stage in the tested varieties. Seed growth rate was the highest from the beginning of the R6 stage to the mid-R6 stage. Chlorophyll content was decreased rapidly in pods and seeds. However, seed growth period from the R6~;to~;R8 was 35 days. The crude protein content was. increased dramatically between 63 DAF and 70 DAF and then increased slightly. The pattern of isoflavone accumulation was nearly similar to that of seed weight increase. From the late R6 stage to the R7 , the accumulation rate was higher as compared to other stages. The angiotensin inhibitory activity was increased according to seed development from 63 (R6 ) to 84 DAF (R8 ). The difference of inhibitory activity in heated soybean powder, however, was not great among stages. The inhibitory activity was affected by heating treatment. The most effective heating time was 10 min. Excessive heating longer than 30 min resulted in a lowered inhibitory activity of soybean on ACE