Jin-Ho Kang’s research while affiliated with Gyeongsang National University and other places

Cotyledon Black Decay (CBD) on soybean sprout mimics the black spot due to microbial infection. CBD, not visible or predictable at seedlot state, for some reason, shows up exclusively on cotyledon of soybean sprout during sprouting process. Such an incidence rate fluctuated from 0.8 to 19.5% over three years from 2004. We suspected some pod-infecting anthracnose fungi and/or pod-blight pathogen, or pod-sucking bean bug, one of the major pests of soybean, might have involved, of which we ruled out fungal pathogen because it was preventable through heat treatment, a proven method for seedlot disinfestation. The healthy seeds artificially fed by bean bug for one to seven days were sprouted, and 6 to 41% of the soybean sprout revealed the CBD mimic to those occurred in soybean sprout from previous commercial seedlot screening experiments. This finding is the first report to confirm that bean bug damage to pod at stage is directly responsible for the CBD, which did not concur with any other deleterious effects on sprouting such as reduction in hypocotyls elongation and rooting except unsightly sprout quality. However, earlier feeding either at green pod or greenish yellow pod stage ( -early stage) resulted in rather severe damages, which strikingly reduced hypocotyls growth to about one forth to about two third, as well as the reduction in rates of seed germination.

Storage conditions of selling mungbean sprouts should affect their marketability. The study was done to examine the effect of light quality (blue, green, yellow, red, far-red) on greening period, shape, fresh and dry weights of mungbean (cv. Zhong Lu 1) sprouts for 5 days to get some information on designing their various polyethylene envelops with different colors. Periods taking to green were 2 to 3.5 days in blue, red and far-red lights but longer than 6 days in green and yellow lights. Yellow lights had the longest total length adding hypocotyl and root, and blue light did the widest hypocotyl diameter while all light treatments showed similar lateral roots for the period. Total fresh and dry weights were the highest in red light but the least in far-red light. Their lengths and weights in green and yellow lights showing the longest periods for their greening declined with increased storage periods but showed no difference between them, meaning that the envelops should be designed mainly by green and yellow colors.

Shoot parts of a monocarpic and short day plant Orostachys japonicus have been used as a herbal medicine. The study was carried out to examine the effect of transplanting time (May 30, June 30, July 30) of its seedlings on its growth, morphological characters, and flowering. Two hours night-break treatment at midnight was done since Aug. 25 when samples were taken afterward every 4 weeks. Growth, morphological and flowering related characters were measured from each sample. Plant height and inflorescence length became longer with delayed transplanting time. Number of leaves including bracts and stem diameter were more and thicker when transplanted on June 30 than two other treatments. Leaves and bracts, stem, root, shoot and total dry weights showed nearly the same result to the number of leaves although floret dry weight were increased as transplanting time was delayed. Although florets were most formed when transplanted on June 30, they were not flowered because of the night-break treatment, meaning that the transplanting time had little effect on its growth and anthesis of the florets.

The content of two steroids-campesterol (1) and -sitosterol (2), and four triterpenes-taraxetrone (5), -amyrin (6), (-)-friedelin (7), glutinol (8) in the Orostachys japonicus A. Berger cultivated under various conditions was estimated and compared with those in wild one. The present investigation disclosed that there are no significant difference in their contents between cultivated Orostachys japonicus A. Berger and wild one. from viewpoint of the content of the steroids 1 and 2, and the triterpenes 5-8, the quality of cultivated Orostachys japonicus A. Berger is not inferior to the wild one.

Shoot weight of Orostachys japonicus should determine its profitability. The study was done to determine the effect of phosphorus and potassium fertilization (0, 5, 10, 20 kg or /1000 ) on its growth, morphological characters, and flowering. Night-break treatment of 2 hours at midnight were done since Aug. 25 when afterward samples were taken every 4 weeks to Nov. 16. Growth, morphological and flowering related characters were measured from each sample. Plant height, inflorescence length, number of leaves including bracts and stem diameter were increased with increased P and K levels. Leaf and bract, floret, shoot and total dry weights showed similar response to the above morphological characters although P fertilization more increased them than K fertilization. Florets were more formed with increased P and K levels but were not flowered due to the night-break treatment, meaning that P and K fertilization had little effect on anthesis of the florets formed.

Traditionally mungbean(Vigna radiata L.) sprouts has been eaten soon after washing. The study was carried out to measure the effect of washing before packaging on morphological characters and color of mungbean sprouts. The seeds of cv. Zhong Lu 1 were soaked in 50 ppm BA solution immediately before 4 hour aeration and then cultured for 6 days. The sprouts were washed immediately before packaged with PE envelops or not, and then stored 5 days at . Their morphological characters, fresh and dry weights, and colors were measured everyday. Compared to washed, nonwashed sprouts had more lateral roots although the two sprouts did nearly same in hypocotyl and root lengths, hypocotyl diameter, fresh and dry weights. Non-washed sprouts, moreover, showed higher brightness in hypocotyl and root and cutting resistance in hypocotyl although there were not significant differences in color a and b, meaning that the latter ones were more rapidly changed during their storage. In non-washed sprouts, number of lateral roots, hypocotyl length and diameter, total fresh and dry weights were nearly same up to 3 days and afterward were declined. Brightness and color b of hypocotyl were decreased with increased storage period although cutting resistance of hypocotyl was since 3 days after storage.

Seedlot disinfection techniques to control mung bean sprout rot caused by Colletoricum acutatum and C. gloeosporioides were evaluated for commercial production scheme. Soaking seedlots in propolis (100 X) and ethanol (20% for 30 min) appeared promising with control values of 85.5 and 80.8 respectively, but still resulted in up to 20% rot incidence. None of the C. acutatum conidia survived through hot water immersion treatment (HWT) for 10 min at temperatures of 55, 60 and , whereas the effective range of the dry heat treatment (DHT) was . Tolerance of mung bean seedlot, as estimated by hypocotyl elongation and root growth, was lower for HWT than for DHT. Germination and growth of sprouts were excellent over the range of intervals, except for HWT at for 5 min. At this marginal condition, heat damage appeared so that approximately 2% of seeds failed to sprout to normal germling and retarded sprouts were less than 5% with coarse wrinkled hypocotyls. These results suggested that DHT would be more feasible to disinfect mung bean seedlots for commercial sprout production. Heat treatment at above ranges was highly effective in eliminating the epiphytic bacterial strains associated with marketed sprout rot samples. HWT of seedlot at 55 and for 5 min resulted in successful control of mung bean sprout rot incidence with marketable sprout quality. DHT at 60 and for 30 min also gave good results through the small-scale sprouting system. Therefore, we optimized DHT scheme at 60 and for 30 min, considering the practical value of seedlot disinfection with high precision and accuracy. This was further proved to be a feasible and reliable method against anthracnose incidence and those bacterial strains associated with marketed sprout rot samples as well, through factory scale mung bean sprout production system.

Anthracnose fungus was most pathogenic on soybean sprout, of the fungi and bacteria isolated from rotten sprout on market. Bacterial strains associated were not virulent. Dry heat (DHT) applied even as high as for 30min. was not effective enough to eliminate the artificially inoculated Colletotrichum gloeosporioides propagules from seedllots. Hot water immersion treatment (HWT), at elevated temperature of for 20 min, did eliminate the pathogen but reduced seed germinating and retarded sprout growth: Seed germination was practically acceptable when the seedlots were exposed to at for 5 min, but about 20% anthracnose propagules survived. Accordingly, we have optimized the HWT scheme for 5 min at . This scheme was validated, at small to large scale production system, that surely rule out the possible carry over of the bacterial contaminant from seedlots. This result should improve the shelf-life of soybean sprout on the market.

Shoot weight of Orostachys japonicus should determine its profitability. The study was carried out to measure the effect of nitrogen (N) fertilization level (0, 5, 10, 20kg/10a) on its growth, morphological characters, and flowering. Night-break treatment of 2 hours at midnight were done since Aug. 25 when afterward samples were taken every 4 weeks to Nov. 16. Growth, morphological and flowering related characters were measured from each sample. Plant height, inflorescence length, number of leaves including bracts and stem diameter were decreased with increased N levels. Leaf and bract, floret, shoot and total dry weights as well as withering rate showed similar response to the above morphological characters. Florets were less formed with increased N levels but were not flowered due to the night-break treatment, meaning that N fertilization had little effect on its growth and anthesis of the florets.

Environment friendly agriculture is nowadays a major fiend to sustain balanced agricultural ecosystem, keeping its productivity. This study was conducted to determine the optimum levels of nitrogen (N) application for improving rice productivity and reducing N loss through N application based on soil diagnosis. four levels of N were applied with 0, 50, 100 and 150% of recommended levels by soil testing in 4 different paddy soils (i.e. normal, sandy, ill-drained and immature soils). Across N treatments, the greatest grain yield was observed in sandy soil and the lowest in ill-drained soil. The grain yield tended to decrease with increasing N application from 50% to 150% of recommended levels, except ill-drained soil. To ensure maximum yield the optimum levels of N application were estimated at 120 kg, 153 kg and 173 kg in normal, immature and sandy soil, respectively.