The metabolism of [14~textrmC ] ~textrmGA12 in the Chinese yam (Dioscorea opposita Thunb. var. Tsukune) was examined to determine the identification of endogenous gibberellins. [14~textrmC ] ~textrmGA12 was metabolized to ~textrmGA53 , ~textrmGA44 , ~textrmGA19 , ~textrmGA20 , ~textrmGA1 , ~textrmGA8 , ~textrmGA15 , ~textrmGA24 , ~textrmGA9 , ~textrmGA36 and ~textrmGA4 . Radioactivity of GAs in non C-13 hydroxylation route was five-fold higher than that of early C-13 hydroxylation in analyzed GA-metabolites. Radioactivity of ~textrmGA4 was always four times higher than that of ~textrmGA1 at every feeding time. ~textrmGA1 radioactivity has always a lower level to below 200 DPM. The major pathway of endogenous GA metabolism in seedlings of the Chinese yam might be the non C-13 hydroxylation pathway.

The purpose of this study was attempted to establish concepts of environmental-friendly applications of flood plain and to suggest the application plans. The results of this study can be summarized as follows; 1.Roles of flood plain as biotop (restoration, preservation, and creation of stream corridor ecosystem) should be considered. 2.Application methods considering environmental and scenic values should be reviewed. 3.Application methods reflecting values as regional ecological resources should be planned. 4.Preservation and application should be considered together, and obtaining a means of living for regional residents and creation of economic profits should be considered together. 5.Land application and approach method by usages (integrated management model) should be applied to utilize and manage flood plain efficiently. 6.Flood plain application programs should be designed reflecting opinions of regional residents. 7.With respect to space planning of flood plain, introduction of facilities focused on ecosystempreservation/ecosystemrestoration/experiences/observation/learning/culture/ recreation/water purification could be reviewed positively.

Endogenous ABA and batatasins were first quantified in the stored tubers and bulbils of the Chinese yam, Dioscorea opposita Thunb. cv. 'Tsukune' by GC-MS with comparison of internal standard, and sugar content was also analyzed by HPLC with comparison of external standard. Endogenous ABA content in stored tubers and bulbils was rapidly decreased as storage period prolonged. ABA content of the bulbils was always higher than that of tuber during storage periods. All batatasins of stored tubers and bulbils at 30 days after storage decreased steadily compared to 120 days after storage. On the contrary, batatasin-Ⅲ of the stored tuber and bulbils was only decreased at 60 days after storage. In Dioscorea opposita Thunb. cv. 'Tsukune' like D. japonica, D. alata, and D. bulbifera, may be controlled by endogenous batatasins and ABA, In these compounds, batatasins rather than ABA might be closely related to dormancy-inducing compound during dormancy of the Chinese yam, Dioscorea opposita Thunb. cv. Tsukune.

Critical nitrogen concentration (Nc), which is defined as the minimum % N in shoots required to maintain the maximum growth rate of top dry weight (W) at any time, was determined for rice plant. Using two rice varietal groups, japonica varieties and an indica ~times japonica "Dasanbyeo", 18 data points fulfilling the statistical criteria for determining Nc were obtained through eight N-fertilization experiments over two years at Suwon (37~circ 16'N), Korea. Nc dilution curve for each variety was obtained by fitting the Nc-W relationship to power function. However, The critical nitrogen curves for the two variety groups were not different statistically. Thus, a Nc dilution curve was fitted for the Nc data points pooled over the two variety groups and proposed in rice as: Nc=4.08, where W＜1.73 t h a-1 , Nc=5.197 W0.425 3/ (R2 =0.964), where 1.73 t h a-1 ＜W＜12 t h a-l . The Nc for W＜1.73 t h a-l were estimated as a constant value of 4.08%, the mean value of the maximum N concentration for N-limiting condition and the minimum N concentration for N non-limiting condition. The model for Nc is applicable to diagnosing the nitrogen nutrition status during the rice growth period from emergence to heading stage. The Nc curve well discriminated the 144 data points between the N limiting and the N non-limiting groups regardless of varieties, cultural methods, and years.-limiting groups regardless of varieties, cultural methods, and years.

One-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (1D SDS-PAGE) was used to determine whether it would provide improved resolving power of hordein proteins concomitant with improved identification of Korean barley cultivars and germplams. This system gave rapid and reproducible separations of hordein polypeptides. Total fourteen of clear and easily scorable subunits were identified in Korean barley cultivars and germplasms and their polymorphic constitutions could provide biochemical genetic information in progeny analysis and endosperm quality improvement in barley breeding programs. Each hordein polypeptides residing in B, C, and D hordein pattern designations were scored to prepare a cultivar catalogue of protein patterns. On the basis of this character, 7 hordein polypeptide patterns were constructed from 108 barley cultivars and experimental lines. The molecular weight of hordein subunits in Korean barley cultivars and experimental lines varied in the range of 98 to 48 kDa. In contrast, less polymorphic hordein polypeptides were found in the low protein barley lines including malting barleys than those found in Korean barley cultivars and experimental lines

Two rice cultivars of the japonica type, ozone-resistant Ilpumbyeo (IL) and ozone-susceptible Keu-mobyeo#l (KM) were exposed to ozone (O3 ) at 0.15 ppm for 30 days. The available nutrient regimes were varied by doubling the supply of nitrogen (N), phosphorus (P) and potassium (K) within a basic fertilizer status (N, P, K; 15, 12, 12 kg l0a-1 ). There was little difference on plant height between ozone-treated and nontreated plants. The most significant ozone stress on tiller number was shown on the 30th day of ozone exposure. Slight recovery from ozone stress was noted on the 60th day. On the 30th day, tiller number was greatly decreased by 40.8% in IL and 64.6% in KM, whereas at a high nitrogen supply regime (2N), it was decreased by 21.4% in IL and 42.7% in KM as compared to the control not treated with ozone at basic fertilizer status. The inhibition of tiller production caused by ozone exposure was alleviated on the 60th day. In both cultivars, number of spikelets per plant and weight of 100 grains were affected little by the ozone treatment irrespective of nutrient regime. However, the number of panicles per plant and yield were reduced significantly. In both cultivars, yield of ozone-treated plants with 2N status was 12.4-16.1 % higher than that of the ozone-treated plants with basic nutrient status. A significant yield decrease of 47.8% and 33.4% was observed for IL and KM, respectively, in ozone-treated plants with higher potassium (2K) status.

Ozone (O3 )-induced changes in chlorophyll content and specific activities of antioxidant enzymes, such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were investigated in two rice cultivars (Oryza sativa L.) grown under variable nutrient treatments. For this study, two rice cultivars of Ilpumbyeo (IL) and Keumobyeo#l (KM), which were known as resistant and susceptible to O3 , respectively, were exposed to O3 at 0.15ppm for 30 days and investigated with 10 days interval. The available nutrient regimes were varied by doubling the supply of nitrogen (N), phosphorus (P) and potassium (K) Within a basic fertilizer status (N, P, K; 15, 12, 12kg/l0a-1 ). In both cultivars and at all nutrient status, chlorophyll content in O3 -treated plants decreased with prolonged treatment period, although higher N, P and K supply with O3 treatment alleviated the decrease in chlorophyll content. The activities of almost all enzymes investigated for this study were decreased during initial stages of O3 - exposure except GPX which maintained higher activity throughout the exposure period than the non-treated plant. However, the antioxidant enzymes in O3 -treated plants showed almost the same or higher activities on 30 days after O3 - exposure. The most significant changes in activities were observed in GR of the O3 -treated leaves. With the prolonged treatment period, the activity of GR at 30 days was increased by 3-8 times compared to those in 10 days. Most of the investigated enzymes showed very similar tendency to O3 treatment in all fertilizer status. There was no observed evidence for enhanced detoxification of O3 -derived activated oxygen species in plants grown under higher fertilizer status compared with that in plants grown under basic fertilizer status. The increase in the activities of SOD, APX and GR in rice leaves by relatively long-term treatment with O3 at low concentration is considered to indicate that the plant became adapted to the O3 stress and the protection system increased its capacity to scavenge toxic oxygen species. Our results in two rice cultivars indicated that there was little difference in the activities of antioxidant enzymes between IL and KM, which were known as resistant and susceptible cultivar to O3

This study selects Sunwol local group, Gusang local group and Yongjun local group to examine the appropriate amount of applied fertilizer in cultivating the double crop seed of Alisma plantago by transplantation in the southern area, improve and complements the double cropping techniques and contribute to stable production. While the plant height is 45,47 and 49cm and the number of leaves is 11.7, 12.5 and 14.4 at non-fertilizing plot, the plant height is 67, 72 and 75cm and the number of leaves is 15.8, 17.2 and 19.3 at all fertilizing plot and their growth is active and in the character of plant height and the number of leaves, especially in the groove of N-P2O5-K2O= 30-15-45kg/10a, the mean plant height of Sunwol is 75cm and mean number of its leaves is 19.3, the mean plant height and number of leaves in Gusang are 72cm and 17.2 respectively and those of Yongjun are 67cm and 15.8 respectively. While the number of floral axis is 1,2 in non-fertilizing plot, that of the whole varieties in all fertilizing plot is 3, 4, 5 and the mean floral axis of Sunwol is N-P2O5-K2O = 10-5-15, 20-10-30, 30-15-45 kg/10a and 18-0-18 of complex fertilizer and 21-17-17kg/10a and it is small in all fertilizing plot. The yield of dry root per 10a is high in all fertilizing grooves and especially in the groove of N-P2O5-K2O = 30-15-45 kg/10a, it is 372.6kg, in the groove of 18-0-18kg/10a using complex fertilizer, it is 389.1kg and in that of 21-17-17kg/10a, it is 376.7kg.6.7kg.

The result of this experiment which are conducted, to improve the cultivation technology of Alisma plantago, to increase its quantity and to contribute for stable production with Yongiun local group by examining the optimal planting density and transplanting period of double cropping of Alisma plantago in the southern region. The characters of plant height, leaf width and length tend to be reduced as the seeding period is later by the order of the 10th, 20th and 30th of July. The period required for flowering is reduced as the transplanting period is later and dense planting is applied. Plant height, the number of leaves and yield of dry root have much quantity at the dense planting density of 20× 15cm as they are transplanted later in the 30th of August or the 10th of September, but they are rather less in sparse planting density of 20×25cm or 20×35cm.

This study was conducted to analyze the responses of some agronomic traits to the different cultural environments and relations among the agronomic traits for selecting sesame varieties with higher cultural stabilities. The indexes for stability parameters measured were coefficient of variability, heritabilities, genetic correlations and path coefficients of agronomic traits according to locations and years in Korea. The heritabilities of agronomic traits showed different by locations and years. Number of seeds per capsule and 1000 seeds weight showed higher heritabilities, but stem length and seed weight per plant showed relatively lower heritabilities. Average heritabilities of some agronomic traits in 1998 were comparatively higher than those of 1999. Of six areas, Jinju area showed biggest coefficient of yield variability in 1998-1999. Iksan and Taegu areas showed higher heritabilities in 1998, but Iksan and Jinju areas showed lower heritabilities in 1999. Genetic correlations were slightly higher than corresponding phenotypic correlations. Stem length showed positive genetic correlation with the number of capsules per plant, and seed weight per plant and the number of capsule per plant showed positive genetic correlation with seed weight per plant. On the analysis of path coefficients, stem length and number of capsules effected highly on grain yield. Great regional variations were observed on the effects of agronomic traits on grain yield. Higher direct effects of stem length on grain yield were observed at Suwon, Chungwon, Taegu, Jinju and Naju areas, but in Iksan area was observed higher direct effect of the number of capsules per plant on grain yield in 1998. In 1999, higher direct effect of stem length on grain yield was observed at Chungwon and Suwon areas. Iksan and Taegu areas were also observed higher direct effect of the number of capsule per plant on grain yield.

Sixteen isolates showing relatively strong antagonicity against the ginger rhizome rot pathogen, Pythium zingiberum, were selected among the 155 isolates from ginger rhizome surfaces and rhizospheres of ginger cultivation fields in Wanju, Chonbuk. The isolate, 'HB 26-5'showing the strongest antagonicity was finally selected by testing duration of inhibition effect and pathogenicity to ginger. The isolated antagonistic microorganism, 'HB 26-5' was rod shape, gram positive and formed endospore. The isolate produced acids utilizing glucose, arabinose, xylose and mannitol, and acetoin at VP test, and grew anaerobically. Temperature range for growth was from 10 to 40℃ . Reaction to catalase and gelatin, hydrolysis were positive, and casein hydrolysis and indol production were negative. Based on the mycological characters and the fatty acid composition, it was identified as Bacillus polymyxa. The pathogenicity test of isolated Bacillus polymyxa 'HB 26-5'on 22 crop cultivars resulted that only the lettuce was influenced in germination, and the others were not affected.

These experiments were conducted to investigate water uptake, electrical conductivity, germination percentage, seedling growth, and seedling establishment rate in direct seeding cultivation of rice. The rice seeds of six japonica type varieties were coated with 12 kinds of polymers in a standard concentration of 0.2% using seed coating machine. The water absorption of the polymer-coated seeds under saturation conditions was not different among varieties, and was the highest in kulcel, maltrin, and waterlock on the polymer-coated seeds. The electrical conductivity with waterlock (55.0 ~mu scm-1g-1 ) was higher than the control plot (45.6 ~mu scm-1g-1 ) and other treatments. The germination of the polymer-coated seeds was 95.9% at control plot, 92.7% at low temperature and 35.7% at high temperature. The total dry weight of seed decreased in the order of low temperature, control plot, and high temperature, and was effective in pvp (polyvinyl pyrrolidone), opadry, and sacrust. The seedling establishment rate in direct seeding cultivation ranged from 74.9 to 81.0% in flooded paddy surface, and ranged from 64.7 to 76.6% in dry paddy. In both cases, it decreased in the order of early, medium and medium-late varieties, but was enhanced in daran 8600, sepirect, and sacrust. According to this study the recommended polymers for direct seeding cultivation of rice are daran 8600, sepirect, and sacrust

Aloe in vitro culture was attempted to induce callus and regeneration ability from different explant sources onto MS medium with 0.5mg/l NAA plus 1.0mg/l BA. Anthers that no developed any callus and plant regeneration, while only four out of 274 filament explants induced calli at cut edge without regenerated plants. Twenty ovary explants regenerated four direct plantlets without via callus from the base of epidermal tissues. Regenerated plants on the root tip gave 2n=14 of chromosome numbers.