• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.33-33
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• 2020

Watermelon (Citrullus lanatus) is a non-seasonal, economically important, cucurbit cultivated throughout the world with Asia as a continent contributing the most. As part of the effort in diversifying watermelon genetic resources in the already cultivated group, this study was devoted to providing baseline data on morphological quality traits and health-beneficial phytonutrients of watermelon germplasm collections, thereby promoting watermelon research and cultivation programs. To this end, we reported morphological traits, citrulline, and arginine levels of watermelon genetic resources obtained from the gene bank of Agrobiodiversity Center, Republic of Korea, and discussed the relationship between each other. Diverse characteristics were observed among many of the traits. But, most of the genetic resources (>90%) were either red or pink-fleshed. Korean origin fruits contained intermediate levels of soluble solid content (SSC) while The USA, Russian, Tajikistan, Turkmenistan, Taiwan, and Uruguay originated had generally the highest levels of soluble solids. The citrulline and arginine contents using HPLC method were ranged from 6.9 to 52.1 mg/g (average, 27.3 mg/g) and 1.8 to 21.3 mg/g (average, 9.8 mg/g), respectively. The citrulline content determined using Citrulline Assay Kit was ranged from 6.5 to 42.8 mg/g (average, 27.0 mg/g). Resources with high citrulline and arginine levels contained low SSC. Whereas, red- and pink-colored flesh samples had less citrulline compared to yellow and orange. In addition to the profiling of morphological characters and phytonutrients, molecular marker characterization and identification of sources of resistance to diseases and pests are recommended for a more complete diversity analysis of watermelon genetic resources.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1999.12a
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• pp.652-660
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• 1999

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.309-314
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• 2014

A total of 67 watermelon accessions which include 37 accessions from Korean and 27 accessions from Turkish germplasm and 3 accessions of other related species from USA were investigated for morphological characteristics. The UPOV descriptor list for 56 characters (6 seedlings, 4 plants, 11 leaves, 5 flowers, 23 fruits and 7 seeds) was used in characterization. In addition, eight quantitative characters, hypocotyl length, cotyledon width, cotyledon length, fruit weight, fruit length, fruit width, thickness of outer layer of pericarp and soluble solid content were also measured. The 56 qualitatively scored characters were analyzed by principle coordinate analysis (PCoA) while the eight quantitative ones were subjected to principle component analysis (PCA). Morphological characterization result demonstrated that the accessions displayed high morphological diversity(how much percent?). A high level of phenotypic diversity was observed from the results of morphological characterization. However, plant growth habit and leaf blade flecking showed constant characters for all of the accessions. The Korean and Turkish watermelon genotypes are diverse groups and can be separated by both multivariate analysis of morphological characters although the grouping was more apparent in PCoS results.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.235-242
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• 2015

The objective of this study was to determine the effects of soluble potassium silicate by soil drenching application on watermelon growth, yield, and nutrient uptake. The potassium silicate rates were control (No potassium silicate), 1.63mM, 3.25mM, 6.50mM. The potassium silicate were treated 6 times (twice before fruit forming and 4 times after fruit forming per 7 day. Soil chemical properties, such as soil pH, EC, available phosphorus and silicate, exchangeable K, nitrate-N levels were increased after potassium silicate treatment, while the concentrations of soil organic matter, exchangeable Ca and Mg were similar to control. The growth characteristics of watermelon, such as stem diameter, fresh and dry weight of watermelon at harvest were thicker and heavier for increased potassium silicate treatment than the control, while number of node, and plant length were same for all treatments. With increased potassium silicate treatment, nutrient concentrations, such as P and K in the watermelon leaf at harvest were increased, N concentration in the leaf was decreased, and Ca and Mg concentrations in the leaf were same. Chlorophyll content was increased with increased potassium silicate application. The occurrence of powdery mildew was lower for the potassium silicate treatments than the control. Fresh watermelon weight for the potassium silicate treatments was 0.1 to 0.5kg per watermelon heavier than the control, sugar content was 0.5 to $0.6^{\circ}Brix$ higher than control, and merchantable watermelon was 2 to 4% increased compared to the control. These results suggest that potassium silicate application by soil drenching method in the greenhouse can improve watermelon nutrient uptake, merchantable watermelon and suppress the occurrence of powdery mildew.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.388-398
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• 2020

Watermelon yield mainly depends on soil water content controlled by irrigation in a plastic greenhouse. In this study, we investigated the effect of different soil moisture contents affected by irrigation starting point on growth, yield, and physiological responses of small-sized watermelons. Irrigation was initiated at 5 different levels of soil water content as a starting point with soil moisture detecting sensor after 14 days of transplanting, and stopped at 7 ~ 10 days before harvest. These treatments were compared with the conventional periodic irrigation as control. When soil had the lowest moisture content (-50 kPa), the overall shoot growth was retarded, but the root length and root dry weight increased. The photosynthetic parameters (photosynthetic rate, stomatal conductance, and transpiration rate) of watermelon leaves decreased significantly in the lowest soil moisture content (-50 kPa). On the other hand, the photosynthetic rates of watermelon leaves grown with irrigation starting point between -20 and -40 kPa were observed to be higher than those of other treatments. Fruit set rate and marketable fruit yield increased significantly at -30 kPa and -40 kPa. Proline, abscisic acid (ABA), total phenol and citrulline, which are known to contribute to stress tolerance under drought condition, increased as soil water content decreased, particularly, the largest increases were recorded at -50 kPa. From these results, it was found that an appropriate water supply adjusted with an irrigation starting point between -30 and -40 kPa could help to keep favorable soil water content during the cultivation of small-sized watermelons, promoting the marketable fruit production as well as inducing the vigorous plant growth and reproductive development.

• Journal of Bio-Environment Control
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• v.27 no.2
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• pp.117-124
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• 2018

Recently, the interest and consumption of mini watermelon (Citrullus lunatus Thunb.) are increasing due to nuclear family and one person household. However, there's no research for mini watermelon. Therefore, the purpose of the study is to develop standard cultivation method of mini watermelon. The test cultivar is 'Minimi', which is a small-sized fruit, the rootstock is 'Bullojangsaeng', which is a cucurbit line. Grafted plants were transplanted on April 5, 2017, and harvested in early July. Cultivated types were 3 methods, which are ${\cap}-form$, arched, and runner type, and plant spacing were 40, 60, and 80 cm, respectively. The rowth and yield in ${\cap}-form$ was higher than that of the arched and runner types, and the sugar content was higher a bit. The yield per unit area was about 50% higher than ${\cap}-form$, which can be plant density cultivation than that of the runner type. The number of seeds per fruit of 'Minimi' was similar to that of 'Sambokggul', but seed weight was one third lower than that of 'Sambokggul'. The content of lycopene was 30% higher than that of 'Sambokggul' watermelon, and the main sugar content is similar to or slightly less. In conclusion, the ${\cap}-form$ staking cultivation was superior to the runner type or arched cultivation in terms of fruit setting ratio, yield and quality.

• Korean Journal of Environmental Agriculture
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• v.38 no.3
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• pp.124-132
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• 2019

BACKGROUND: Silver grass (Miscanthus sinensis) No. 1 was developed for production of bio-ethanol, and for the purpose the silver grass growing sector was established in Geumgang basin, Iksan, Jeonbuk, in 2011. However, the other application potentials except for using as the bio-energy resources should be considered because of the drop in international oil prices. Therefore, there is the necessity of a scientific basis to use the silver grass instead of rice straw as the organic matter source that is used for improvement of soil quality in the plastic film house. METHODS AND RESULTS: The silver grass was applied at 5, 10, 15 and 20 Mg/ha and tilled before the watermelon was planted in the plastic film-house. The control plot was treated with 10 Mg/ha with rice straw, and watermelons have been cultivated for 3 years(2017~2019). Soil aggregation, soil chemistry, and the growth characteristics were investigated, when the watermelon was harvested every year. Soil aggregation levels at the 2nd and 3rd year of watermelon harvest were similar from the plot applied with the silver grass at 5 Mg/ha and the control plot, and increased in the silver grass treated plots with more than 10 Mg/ha. However, there was no statistically significant difference between the plots. The nitrogen mineralization of silver grass in the control plot tended to be similar to the 5 Mg/ha plot, but the silver grass treated plots with over 10 Mg/ha showed low nitrogen mineralization. Soil EC on harvest stage was proportional to the applied mass of the silver grass, but pH was in inverse with the applied mass. Soil organic matter content, available phosphate, and exchangeable cations increased with the continued use of silver grass. Watermelon weight found to be the best on more than 15 Mg/ha of silver grass, and the sugar content was highest when 10 Mg/ha was treated. CONCLUSION: The use of the silver grass at 10 Mg/ha annually as the organic source was effective in replacing rice straw while growing fruits and vegetables on the plastic film house.

• Research in Plant Disease
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• v.15 no.1
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• pp.51-53
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• 2009

The fruit rot of watermelon (Citrullus lanatus) occurred sporadically in the farmers field at Chojeondong, Jinju city, Korea, in 2007. The typical symptom was water-soaked, brown on the fruit, and than infected fruits were mostly rotted. White mycelial mats were spread over lesions, and then sclerotia were formed on fruit and near soil line. The sclerotia were globoid in shape, $1{\sim}3\;mm$ in size and white to brown in color. The optimum temperature for mycelial growth and sclerotia formation on PDA was $30^{\circ}C$ and the hyphal width was $4{\sim}8{\mu}m$. The typical clamp connections were observed in the hyphae of the fungus. On the basis of mycological characteristics and pathogenicity to host plants, this fungus was identified as Sclerotium rolfsii. This is the first report on the fruit rot of watermelon by S. rolfsii in Korea.

• Research in Plant Disease
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• v.12 no.2
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• pp.125-128
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• 2006

Downy mildew caused by Pseudoperonospora cubensis (Berkeley & Curtis) occurred on the cotyledon of gourd (Lagenaria leucantha cv. Sambokkkul) and scion of watermelon (cv. FR couple) in commercial nursery around Jinju city, Gyeongnam province in Korea in 2005 and 2006. The disease symptoms usually started with water-soaking lesions on cotyledon and then the infected leaves became withered and eventually died. The sporangia of the pathogen were one-celled, ovoid to ellipsoid in shape, pale grayish in color, and $20{\sim}32{\times}14{\sim}18{\mu}m$ in size. Sporangiophores were errect, branched, and $140{\sim}380{\times}4{\sim}8{\mu}m$ in size. Pathogenicity of the causal organism was proved according to artificial inoculations. Although the virulence of the causal fungus on the host plants was not strong, it produced typical symptoms. The causal organism was identified as Pseudoperonospora cubensis (Berkeley & Curtis) based on the mycological characteristics of the fungus and pathogenicity. This is the first report on downy mildew of watermelon caused by P. cubensis in Korea.

• Horticultural Science & Technology
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• v.33 no.3
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• pp.409-419
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• 2015

This study was conducted to establish an efficient screening method for watermelon plants resistant to Fusarium wilt (FW), which is caused by Fusarium oxysporum f. sp. niveum (Fon). An HA isolate was prepared from a wilted watermelon plant in Haman-gun and identified as F. oxysporum f. sp. niveum based on morphological characteristics, molecular analyses of ITS (internal transcribed spacer) and TEF (translation elongation factor $1{\alpha}$) sequences, and host specificity on cucurbits including watermelon, melon, oriental melon, and cucumber. The assay for disease response of watermelon differentials indicated that the HA isolate was race 0. Among seven liquid media tested, the highest amount of Fon spores was produced from V8-juice broth, which was selected as a medium for mass production of Fon. The disease assay for 21 watermelon and 11 watermelon-rootstock cultivars demonstrated that 20 watermelon cultivars except for 'Soknoranggul' were susceptible; 'Soknoranggul' was moderately resistant. All the tested rootstock cultivars were highly resistant to the HA isolate. The evaluation of disease development depending on various conditions suggested that an efficient screening method for FW resistance in watermelon plants is to dip the roots of 10-day-old seedlings in spore suspension of $1.0{\times}10^5-1.0{\times}10^6conidia{\cdot}mL^{-1}$ for 30 min., to transplant the seedlings to plastic pots with a fertilized soil, and then to cultivate the plants at $25^{\circ}C$ for 3 weeks.