• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.1
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• pp.69-89
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• 1981

Stevia (Stevia rebaudiana Bertoni) is a perennial herb widely distributed in the mountainous area of Paraguay. It belongs to the family Compositae and contains 6 to 12 percent stevioside in the leaves. Stevioside is a glucoside having similar sweetening character to surgar and the degree of sweetness is approximately 300 times of sugar. Since Korea does not produce any sugar crops, and the synthetic sweetenings are potentially hazardous for health, it is rather urgent to develop an economical new sweetener. Consequently, the current experiments are conducted to establish cultural practices of stevia, a new sweetening herbs, introduced into Korea in 1973 and the results are summarized as followings: 1. Days from transplanting of cuttings to the flower bud formation of 6 stevia lines were similar among daylengths of 8, 10 and 12 hours, but it was much greater at daylengths of 14 or 24 hour and varietal differences were noticable. All lines were photosensitive, but a line, 77013, was the most sensitive and 77067 and Suweon 2 were less sensitive to daylength. 2. Critical daylength of all lines seemed to be approximately 12 hours. Growth of plants was severely retarded at daylengths less than 12 hours. 3. Cutting were responded to short daylength before rooting. Number of days from transplanting to flower bud formation of 40-day old cuttings in the nursery bed was 20 days and it was delayed as duration of nursery were shorter. 4. Number of days from emergence to flower bud formation was shortest at short day treatment from 20 days after emergence. It was became longer as initiation of short day treatment was earlier or later than 20 days. 5. Plant height, number of branches, and top dry weight of stevia were reduced as cutting date was delayed from March 20 to May 20. The highest yield of dry leaf was obtained at nursery duration of 40-50 days in march 20 cutting, 30-40 days in April 20 cutting, and 30 days in May 20 cutting. 6. An asymptotic relationship was observed between plant population and leaf dry weight. Yield of dry leaf increased rapidly as plant population increased from 5,000 to 10,000 plants/10a with a reduced increasing rate from 10,000 to 20,000 plants/l0a, and levelled off at the plant population higher than 20,000 plants/l0a. 7. Stevia was adaptable in Suweon, Chengju, Mokpo and Jeju and drought was one of the main factors reducing yield of dry leaf. Yield of dry leaf was reduced significantly (approximately 30%) at June 20 transplanting compared to optimum transplanting. 8. Yield of dry leaf was higher in a vinyl house compared to unprotected control at long daylength or natural daylength except at short day treatment at March 20. Higher temperature ill a vinyl house does not have benefital effects at April 20 transplanting. 9. The highest content of stevioside was noted at the upper leaves of the plant but the lowest was measured at the plant parts of 20cm above ground. Leaf dry weight and stevioside yield was mainly contributed by the plant parts of 60 to 120cm above ground but the varietal differences were also significant. 10. Delayed harvest by the time of flower bud formation increased leaf dry weight remarkably. However, there were insignificant changes of yield as harvests were made at any time after flower bud formation. Content of stevioside was highest at the time of flower bud formation and earlier or later harvest than this time was low in its content. The optimum harvesting time determined by leaf dry weight and stevioside content was the periods from flower bud formation to right before flowering that would be the period from September 10 to September 15 in Suweon area. 11. Stevioside and rebaudioside content in the leaves of Stevia varieties were ranged from 5.4% to 14.3% and 1.5% to 8.3% respectively. However, no definit relationships between stevioside and rebaudioside were observed in these particular experiments.

• Korean Journal of Environmental Agriculture
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• v.32 no.1
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• pp.55-60
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• 2013

BACKGROUND: The buds of persimmon trees are susceptible to cold damage, often with the late frost, at the time of budburst. This study was conducted to determine effect of the cold damage on shoot and fruit growth the current season. METHODS AND RESULTS: 'Fuyu' trees, grown in 50-L pots, were placed for 1 h at $-2.2{\pm}0.5$, $-2.6{\pm}0.5$, or $-3.0{\pm}0.5^{\circ}C$ within a cold storage, at their budburst on April 5. Some trees under ambient temperature at $10-17^{\circ}C$ served as the control. Cold damage of the buds containing flower buds was 54% at $-2.2^{\circ}C$, and significantly increased to 95% at $-3.0^{\circ}C$. The bud damage included the complete death of all, complete death of main buds only, or the late and deformed shoot growth in the spring. Number of flower buds in early May dramatically decreased as the damage ratio increased. Since the thinning of flower buds in mid-May and fruitlets in early July was done in no or slightly damaged trees, the final number of fruits and yield did not decrease compared with the control when the damage increased by 60% and 70%, respectively. Average fruit weight and skin coloration tended to be better with increasing bud damage. Shoot growth was more vigorous in those trees whose buds were severely damaged by low temperature. CONCLUSION(S): Shoot growth and the yield may depend on the number of flower buds and percent fruit set after the cold damage.

• Korean Journal of Plant Resources
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• v.25 no.1
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• pp.156-168
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• 2012

Chrysanthemum is a cut flower species that normally lasts for 1 to 2 weeks, in some cases 3-4 weeks. This has been attributed to low ethylene production during senescence. Reduction in cut flower quality has been attributed to the formation of air embolisms that partially or completely blocks the water transport from the vase solution to the rest of the cut flower stem, increasing hydraulic resistance which may cause severe water stress, yellowing, wilting of leaf, and chlorophyll degradation. Standard type chrysanthemum can be harvested when buds were still tightly closed and then fully opened with the simple bud-opening solution. Standard type chrysanthemum can also be harvested when the minimum size of the inflorescence is about 5-6 cm bud which opened into the first flower full-sized flower. While spray varieties can be harvested when 2-4 most mature flowers have opened (40% opening). Cut flowers are sorted by stem length, weight, condition, and so on. Standard chrysanthemum is 80 cm length for standard type and 70cm for spray type. Pre-treatment with a STS, plant regulator such as GA, BA, 1-MCP, chrysal, germicide, and sucrose, significantly improved the vase life and quality of cut flowers. It is well established that vase solutions containing sugar can improve the vase life of cut chrysanthemum. Chrysanthemum is normally packed in standard horizontal fiberboard boxes. Chrysanthemum should normally be stored at $5{\sim}7^{\circ}C$. Precooling resulted in reduction in respiration, decomposition, and transpiration activities as well as decoloration retardation. There was significant difference between "wet" storage in 3 weeks and "dry" storage in 2 weeks. In separate pulsing solution trials, various germicides were tested, as well as PGRs to maintain the green color of leaves and turgidity. Prolonging vase life was attained with the application of optimal solution such as HQS, $AgNO_3$, GA, BA and sucrose. This also retarded senescence in leaves of cut flower stems. Fresh cut chrysanthemum can be transported using a refrigerated van with $5{\sim}7^{\circ}C$. Increasing consumption and usage of cut chrysanthemum of various cultivars would require efficient transport system, and effective information exchange among producer, wholesaler, and consumer.

• Korean Journal of Plant Resources
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• v.20 no.4
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• pp.292-297
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• 2007

To explain the relationship between plant size and seed production, change of sexual organs, relationship between each organs of Convallaria keiskei population, which is located in Gwiyeo-2-ri, Namjong-myeon, Gwangju-si, Gyeonggi-do these were studied from April to August 2002. This study was carried out two ways. One way was to set up the permanent quadrat to explain the change of sexual organs. The other was to carry the collected sample to the laboratory and analysis it to explain the relationship between each organs and energy division of seed production. In the Convallaria keiskei population, the average number of leaf which blooming shoot in the permanent quadrat was 2 and I could find the late leaf size was larger. It was found that, per shoot, the average number of flower was 7.9, fruit was 5.4 and seed was 16.1. Each properties in the sexual organ, underground part size and leaf size, had correlation of 1% or within 5%. The flowering time of the Convallaria keiskei was from April 26 to May 11. Therefore, it can be estimated that the blooming period was $8{\sim}9$ days in just one flower. Among that flowers bloom at the beginning May, 80% fruit at the end of May, and 68% fruit at the end of August. The dry weight of seed had more correlation dry weight of underground part than leaf area.

• Journal of Bio-Environment Control
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• v.7 no.2
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• pp.116-122
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• 1998

This study was conducted to investigate growth and flowering of hydroponically-grown carnation as affected by substrate and planting date, Three substrates, coir, perlite, and coir＋perlite(1：1. v/v), and two planting dates. May 1 and September 1 were used. Plant height and stem diameter at harvesting time of cut flowers were greater for the September 1 planting than for the May 1 planting. The plants planted on May 1 produced flowers with weak stems and short stem lengths. In addition, flower weight and blossom width were gloater for the September 1 planting than for the Mar 1 planting. The planting date had no significant effect on the number of petals, The carnation planted on May 1 flowered 50 days earlier compared to those Planted on September 1. Plant height and number of petals were the greatest in the plot of coir substrate. The results indicated that for commercial production of cut carnations in a hydroponic system, planting on September 1 is better than May 1. In addition. the results confirm that coir is the superior substrate for the production of cut carnations in a hydroponic system compared to either Perlite or coir＋perlite mixture.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.17
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• pp.79-114
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• 1974

Experiments were conducted to clarify the variations of the ecological characteristics under different day-length and temperature conditions inperilla varieties from 1972 to 1973 in the experimental fields of Crop Experiment Station, O.R.D, Suwon. Thirty-six varieties were tested in the field in 1972 under 6 growing seasons differing seeding dates. from April 5th to June 20th with 15-day interval between each seeding. Pot-experiment also were conducted in 1972 and 1973. The seeds of the 6 varieties tested were sown on May 25th. In this pot-experiment natural condition was regarded as a short-day treatment and 100-W incandescent lamps were used for long-day treatment. Three selected varieties were grown under different. temperature treatments in phytotron in Crop Experiment Station. The results obtained are summarized as follows: 1. Most varieties tested flowered around September 6. The days required to flower were shortened gradually as the planting time was delayed. 2. The varieties used were matured around October 6, but the maturity was shortened when planted early. The days required for maturity after flowering was 26 to 30. 3. The growing period was also shortened gradually when planting time was delayed. 4. Plant height was reduced when planting time was delayed. 5. There were little differences in number of valid branches among planting time I, II and III, while the branch number was reduced as the planting time was delayed. 6. The dry matter weight was gradually increased from planting time I to III, while it was rapidly decreased after planting time IV. 7. It was found that the flowering of perilla was little affected by temperature. The varieties, however, were more sensitive to day-length. 8. No clear tendency was found in the plant height, number of valid branches and dry matter weight by the time and period of day-length and temperature treatments. 9. The highest yield was obtained at planting time III(May 5th) and the yield was decreased at either earlier or later planting. 10. 1, 000 grain weight appeared to be heavier as the planting time was delayed. 11. The number of flower cluster was largest at planting time III (May 5th) and it was decreased as planting time was earlier or later than III. 12. The oil content was also highest at planting time III (May 5th). 13. Days to flowering, days to maturity and total growing period and flowering period did not affect the yield much. 14. The number of valid branches, flower clusters, 1, 000-grain weight and dry matter weight were positively correlated with yield. The relationship between these characters and yield were variable depending upon the planting time.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.555-559
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• 2001

This research was conducted to estimate the chlorophyll contents of chrysanthemum leaves using SPAD-502 chlorophyll meter under different photoperiod and light intensity. Measurements were done at every third leaf intervals starting from the top of the stem to the bottom at harvest time. SPAD value was highest at 10 hours of photoperiods, followed by 13 and 16 hours of photoperiods. In particular, under short day condition, SPAD value was highest in the young leaves below the flower bud and decreased down the leaf profile. Under long day condition, SPAD value reached maximum at leaves between $15-27^{th}$ from the top and decreased to the minimum immediately below the flower bud (youngest leaf). These results may indicate that the younger leaves become strong source of supporting flowers in reproductive stage, while the younger leaves serve as sinks and older leaves support their development in vegetative stage. Changes of SPAD value at different levels of irradiance showed that highest SPAD value were observed at high irradiance and decreased with decreasing irradiance.

• The Plant Pathology Journal
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• v.31 no.3
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• pp.212-218
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• 2015

In this study, we developed a species-specific PCR assay for rapid and accurate detection of three Xanthomonas species, X. axonopodis pv. poinsettiicola (XAP), X. hyacinthi (XH) and X. campestris pv. zantedeschiae (XCZ), based on their draft genome sequences. XAP, XH and XCZ genomes consist of single chromosomes that contain 5,221, 4,395 and 7,986 protein coding genes, respectively. Species-specific primers were designed from variable regions of the draft genome sequence data and assessed by a PCR-based detection method. These primers were also tested for specificity against 17 allied Xanthomonas species as well as against the host DNA and the microbial community of the host surface. Three primer sets were found to be very specific and no amplification product was obtained with the host DNA and the microbial community of the host surface. In addition, a detection limit of $1pg/{\mu}l$ per PCR reaction was detected when these primer sets were used to amplify corresponding bacterial DNAs. Therefore, these primer sets and the developed species-specific PCR assay represent a valuable, sensitive, and rapid diagnostic tool that can be used to detect three specific pathogens at early stages of infection and may help control diseases.

• Journal of Life Science
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• v.20 no.2
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• pp.219-224
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• 2010

This study was carried out to develop the breeding and cultivation of Allium grayi by investigating its natural habitats in Korea. The number of sunny, half-shady, and shady natural habitats were 194 (64.0%), 96 (31.7%), and 13 (4.3%), respectively. Natural habitats included upland (51.2%), Buddhist temple (18.8%), mountain (11.6%), roadside (7.9%), river (5.9%), paddy field (2.3%), and seashore (2.3%). Natural habitats ranged widely in all areas between $33^{\circ}N{\sim}38^{\circ}N$ and $126^{\circ}E{\sim}130^{\circ}E$. Self-generation patterns included growing spontaneously with a 1~10m distance between plants, and there were 3~5 bulbils around each bulb. The sprout stage began in September and continued until March of next year in natural habitats. The bolting period was May, with the following three patterns: tuber (59.2%), flower and tuber (24.7%), and flower (16.1%).

• Horticultural Science & Technology
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• v.16 no.4
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• pp.531-532
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• 1998

This study was conducted to investigate the optimum concentration and time of BA treatments for the improvement of flowering in Cymbidium encifolium 'Tekkotsusosin'. The flowering rate was increased by the higher concentration of BA treatment, and reached 100% by $400mg{\cdot}L^{-1}$ treatment. But high concentration induced the flower malformation. Therefore, the optimum concentration of BA for increased of flowering rate was about $300mg{\cdot}L^{-1}$. In the time of BA treatment, plants which were treated in June to August by BA $300mg{\cdot}L^{-1}$ were flowered, especially up to 100% in August. However, those treated in April, May, and September did not.