Humankind has been searching for medicinal materials from various plant sources in an attempt to treat disease. Mistletoe is one indubitable plant source for these materials due to its effectiveness in treating various diseases, but it has almost disappeared from the mountainous areas of Korea due to excessive harvesting. In this study, in order to select host tree species for Korean mistletoe [Viscum album var. coloratum (Kom.) Ohwi] by seed inoculation and to clarify the effect of host specificity among various tree species were conducted for the purpose of gaining basic information for the artificial cultivation of Korean mistletoe. Almost all the seeds of Korean mistletoe germinated in vitro at the temperature of 15℃. Among host trees used in this study, Prunus mume showed the highest parasitic affinity with inoculated Korean mistletoe, compared with any other host plants. However, treatment of hormones could not increase the low survival rate of Korean mistletoe on the host trees.

Rhododendron brachycarpum is a evergreen broad-leaved shrub and belongs to the Ericaceae family and the Rhododendron genus. It is well known for its beautiful leaves and flowers. There are 11 species of the Rhododendron genus in Korea. It includes 3 species - Rhododendron brachycarpum, Rhododendron aureum Georgi and Rhododendron brachycarpum var. roseum Koidz. They grow naturally over 1,000 meters above sea level of the Baekdu Mountain Range in Korea. These habitats, according to investigations of 9 Rhododendron brachycarpum natural habitats, are mostly located on the slope of mountains facing north at an altitude of 1,200 m to 1,526 m above sea level with angle of inclination from 30 degrees to 45 degrees. Based on the result of vegetation analysis of dominance species in the quadrates, there are Quercus aliena, Quercus mongolica Fisch. ex Ledeb, Abies holophylla in species of upper trees, and so on. Dominant species of woody plants in tree layer are Quercus aliena, Quercus mongolica Fisch. ex Ledeb, Abies holophylla, Betula platyphylla and Veeatrum patulum Loes. fil, Erythronium japonicum, Dryopteris crassirhizoma, Paeonia japonica var. glabra Makino are founded in herbaceous plants. And we can see another result of the investigation that the flowering rates of the plants with the buds are highly ranked mountains such as Mt. Hambaek 68%, Mt. Gyebang 40%, Mt. Yagksu 9%, Mt. Gaein 7% and Mt. Seolag 0%. The results show that there are 24 over 15-year-old Rhododendron brachycarpums in Mt. Odae and are 56 under 15-year-old trees in Mt. Hambaek and are no trees in Mt. Gyebang and are 9 over 30-year-dead trees only in Mt. Taebaeg. Out of found trees, the highest tree is 7 m in height and 0.6 m in diameter. Also this result shows what are the vulnerability factors of the natural habitats. They are as follows: indiscriminate trails in mountains, damages by mountain climbers, uncareful plant collecting, the fierce competitions with other plants such as Acer pseudosieboldianum var. ishidoyanum Uyeki, Quercus aliena, Celastrus orbiculatus and damages by disease and insect, unusual temperature in natural habitats, etc. Rhododendron brachycarpums have high ornamental value and excellent pharmaceutical effect. But the areas of its habitats decrease dramatically. So we need measures to protect and their natural habitats. It is necessary that we conduct further investigations to designate conservation area for Rhododendron brachycarpums.

Nitrogen (N) fertilization is essential for alleviating nutrient deficiencies of the world’s population by increasing rice production, one of the most important food crops of our time. Here we established an in vivo hydroponics rice seedling culture system to investigate the physio-biochemical and molecular responses of various rice genotypes to low nitrogen application. Yoshida’s nutrient solution (YS) was used to grow rice seedlings, and at three-week-old the seedlings manifested highly stable and reproducible symptoms, such as reduced shoot growth and length. Out of 12 genetically selected or tested genotypes, almost all (11 genotypes) showed varied degrees of growth reduction response to applied nitrogen (4 and 40 ppm N for treatment and control, respectively), but SR19663-B-B-34-3-3-3-1 showed similar growth as the control though its leaf width was smaller than the control. The leaves of a 11 representative low nitrogen-responsive genotype as BG90-2 were sampled for revealing the protein profiles between low and normal (control) nitrogen application by using two-dimensional gel electrophoresis (2-DGE) followed by staining of separated proteins with silver. Fifty differentially expressed silver stained protein spots were excised from 2-D gels and 41 proteins identified using high-throughput mass spectrometry (MS) using matrix-assisted laser desorption/ionization-time of flight-MS and nano electrospray ionization liquid chromatography tandem MS. These proteins could be assigned as major (energy metabolism, photosynthesis and oxidative stress) and minor functional categories, revealing many novel low N-responsive proteins, including those having energy/photosynthesis, and defense/stress, and iron homeostasis-related functions.

본 실험은 질소시용 수준이 수도의 이삭줄기, 엽신 및 엽초의 소유관속 발육에 미치는 영향을 구명 하여 수량을 증대시킬 수 있는 방안을 모색하기 위하여 '89∼'90년에 국제벼연구소 (IRRI)에서 인도형인 IR 58과 일본형인 운봉 7을 공시하여 수행하였다. 1. 분얼경의 수수절간에 발달된 소유관속수는 질소시용 수준이 증가할수록 유의하게 증가되는 경향이었으며, 주간의 경우 질소 무시용구에 비하여 질소시용구에서 IR 58은 39% 및 운봉 7은 24% 증가하였다. 2. 주간 및 일찍 출현된 1, 2차 분얼경의 발육 순서로 소유관속수가 많이 발육되어 있었으며, 분얼경의 출현이 늦을수록 유관속의 발육이 저하 되었다. 3. 주간의 수수절간, 엽신 및 엽초의 소유관속발육은 질소 무비구 및 소비구에 비하여 질소 증시구에서 다소 증가하는 경향이었다. 4. 수수절간의 소유관속수는 이삭당 영화수 및 입중과 밀접한 정의 상관관계를 나타냈으며, 이는 줄기에 발달된 소유관속이 영화수의 분화와 깊은 연관성을 가지고 있으며, 발달된 유관속을 통해 양수분 전류가 원할히 이루어져서 결국 이삭당 입중도 증가되는 결과를 보였다.