• The Plant Pathology Journal
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• v.31 no.4
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• pp.379-387
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• 2015

Melon necrotic spot virus (MNSV) was recently identified on watermelon (Citrullus vulgaris) in Korea, displaying as large necrotic spots and vein necrosis on the leaves and stems. The average occurrence of MNSV on watermelon was found to be 30-65% in Hapcheon and Andong City, respectively. Four isolates of the virus (MNSV-HW, MNSV-AW, MNSV-YW, and MNSV-SW) obtained from watermelon plants in different areas were non-pathogenic on ten general indicator plants, including Chenopodium quinoa, while they infected systemically six varieties of Cucurbitaceae. The virus particles purified by 10-40% sucrose density gradient centrifugation had a typical ultraviolet spectrum, with a minimum at 245 nm and a maximum at 260 nm. The morphology of the virus was spherical with a diameter of 28-30 nm. Virus particles were observed scattered throughout the cytoplasm of watermelon cells, but no crystals were detected. An ELISA was conducted using antiserum against MNSV-HW; the optimum concentrations of IgG and conjugated IgG for the assay were $1{\mu}l/ml$ and a 1:8,000-1:10,000 dilutions, respectively. Antiserum against MNSV-HW could capture specifically both MNSV-MN from melon and MNSV-HW from watermelon by IC/RT-PCR, and they were effectively detected with the same specific primer to produce product of 1,172 bp. The dsRNA of MNSV-HW had the same profile (4.5, 1.8, and 1.6 kb) as that of MNSV-MN from melon. The nucleotide sequence of the coat protein of MNSV-HW gave a different phylogenetic tree, having 17.2% difference in nucleotide sequence compared with MNSV isolates from melon.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.351-358
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• 2016

This study investigated the effect of different relative humidity (RH) regimes on graft healing of grafted seedlings of watermelon (Citrullus vulgaris Schrad.). Two watermelon cultivars ('Speed' and 'Sambok Honey') were grafted onto the 'RS-Dongjanggun' bottle gourd rootstock (Lagenaria siceraria Stanld.) and the grafted seedlings were maintained under one of three relative humidity regimes, 95-96% [1.1-0.8 (day) or $0.8-0.6(night)\;g{\cdot}m^{-3}$ vapor pressure deficit (VPD)], 97-98% [ 0.7-0.4 (day) or $0.5-0.3(night)\;g{\cdot}m^{-3}$ (VPD)], or 99-100% [0.3-0.0 (day) or $0.2-0.0(night)\;g{\cdot}m^{-3}$ (VPD)] according to the Mollier diagram based on the air temperature of $25^{\circ}C\;day/18^{\circ}C\;night$ with 16 h photoperiod per day. Among the RH treatments, 97-98% significantly increased plant height and fresh weight of the rootstock and scion of the 'Speed' and it also enhanced the graft union connection of both cultivars after two days of grafting. However, plant height and thickness of the scion of 'Sambok Honey' was increased by the 99-100% RH treatment. Furthermore, both cultivars grown in the 95-96 and 97-98% RH treatments consisted of lower levels of endogenous $H_2O_2$ and less activities of antioxidant enzymes which illustrated the occurrence of less oxidative stress. Hence, the results of this study identified the optimal RH level for the graft healing of watermelon seedlings.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.37-45
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• 2007

The genetic transformation of watermelon by Agrobacterium has been known very difficult and a few successful cases have been reported by obtaining the direct shoot formation. However, since this direct shoot formation is not guaranteed the stable transformation, the stable transformation with reproducibility is required by a different approach such as a callus induced manner. The best conditions for inducing the callus from cotyledon and root explants of watermelon were 2 mg/L zeatin + 0.1 mg/L IAA and 2 mg/L BA + 0.1 mg/L 2,4-D, respectively. The GFP expression in the callus was identified and monitored through fluorescent microscopy after transformation with pmGFP5-ER vector. Paromomycin rather than kanamycin was used for selecting the nptll gene expression because it was more effective to select the watermelon explants. Four different callus types were observed and the solid green callus showed stronger GFP expression. The highest frequency of GFP expression in the callus developed from cotyledon was 9.0% (WM8 inbred line), while the highest frequency from root was 8.3% (WM6 inbred line). The WMV-CP was transformed using the method of GFP transformation and the genetic transformation of WMV-CP was confirmed by PCR and Southern blot analysis. Here we present a system for callus induction of watermelon explant and the callus induced method would facilitate the establishment of stable watermelon transformation.

• Journal of Bio-Environment Control
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• v.10 no.4
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• pp.232-236
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• 2001

Four air temperature levels of 23, 25, 27 and 29$^{\circ}C$, three humidity levels of 85, 90 and 95% R.H. at photosynthetic photon flux (PPF) of 50 $\mu$mol.m$^{-2}$ .s$^{-1}$ were provided to investigate the effect of vapor pressure deficit on the evapotranspiration rate (EVTR) and graft-taking of watermelon grafted seed-increase. Thus EVTR of grafted seedlings increased with increasing air temperature at high humidity of 95%R.H. At relatively low humidity of 85% R.H., grafted seedlings showed a high EVTR and some wilting of scions was observed at this condition. This result would be ascribed to the low supply of water to vascular bundles according to the insufficient joining of scions and rootstocks. Differences in EVTR between 90% R.H. and 95% R.H. were not observed. Grafted seedlings showed high graft-taking at high relative humidity. Relative humidity had highly influenced to the graft-taking as compared to the air temperature. Graft-taking increased with decreasing vapor pressure deficit. Graft-taking greater than 90% was found at vapor pressure deficit less than 0.4kPa which could be obtained at humidity higher than 90% R.H. Therefore it is required to control the humidity higher than 90% R.H. for suppressing EVTR of grafted seedlings and preventing some wilting of scoins and thus enhancing the graft-taking of grafted seedlings.

• Journal of Bio-Environment Control
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• v.19 no.3
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• pp.130-134
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• 2010

To investigate effects of deep tillage before planting on physicochemical properties of soil, growth and fruit characteristics in cultivation of watermelon (Citrullus vulgaris L. cv. 'Uriggul') under plastic film house, this study was conducted in cultivating field of Gochang Junbuk. pH in soil after harvest compared with soil before planting of watermelon had almost no change, but EC lowed greatly in the two treatments. Available phosphate concentration in the soil with the deep tillage treatment was lower, K concentration of exchangeable cation decreased greatly than these with conventional tillage treatment. In the growth at 27th day after planting plant, stem length to 10th node from the first node, leaf width with deep tillage treatment were longer, bearing node of the first and second flower and wilting degree were lower than these with conventional tillage treatment. In the growth of harvesting time, the stem length to 30th node from the first node with the deep tillage treatment were longer, leaf discoloration degree was lower than these with conventional tillage treatment. Also, the harvested fruits length, diameter, peel hardness, and weight were significantly better than these with conventional tillage treatment.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.166-170
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• 2008

The effects of heat treatments on the antioxidant activities of selected fruits and vegetables were investigated by heating at various temperatures (110, 120, 130, 140, and 150$^{\circ}C$) for 2 hr. The examined fruits and vegetables included tomatoes (Lycopersicon esculentum), oriental melon (Cucumis melon var. makuwa), apples (Malus pumila Miller var. domestica Schneider), melon (Cucumis melon), watermelon (Citrullus vulgaris), and banana (Musa sapientum). The total polyphenol and total flavonoid contents of the juices from heated samples were quantified spectrophotometrically, and their antioxidant activities were determined using DPPH and ABTS radicals. As the heating temperature increased, antioxidant activity also increased. The highest total polyphenol content (2.80 mg/g) occurred in the oriental melon with heating at 150$^{\circ}C$, and this value was 7 times higher than that of the untreated oriental melon (0.40 mg/g). The highest total flavonoid content (148.80 ${\mu}$g/g) occurred in the melon heat treated at 150$^{\circ}C$, and this value was 37 times higher than that of the untreated melon (4.54 ${\mu}$g/g). DPPH radical-scavenging activity was the highest in the watermelon treated at 150$^{\circ}C$ (84.37%, 0.50 mg/g), and this value was 40 times higher than that of the untreated watermelon. Finally, the highest ascorbic acid (AA) equivalent antioxidant capacity (AEAC) value (239.50 mg AA eq/g) was obtained in the watermelon heat treated at 150$^{\circ}C$ for 2 hr (control = 18.35 mg AA eq/g).

• Korean Journal of Organic Agriculture
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• v.26 no.4
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• pp.677-686
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• 2018

This study was carried out to determine the effect of Kluyvera sp. CL-2 (KACC 91283P) on the growth of watermelon (Citrullus vulgaris L.). The study consisted of three treatments, no treatment (NT), twice application of Kluyvera sp. CL-2 before transplanting (KC1), and five times application around transplanting (KC2). We determined the chemical properties of soil before and after the treatments, and compared the growth characteristics of watermelon among treatments. The treatment of Kluyvera sp. CL-2 at $1.0{\times}10^6cfu\;mL^{-1}$ significantly increased available $P_2O_5$. The organic matter showed to increase for all treatments, while soil pH, exchangeable Ca and Mg tended to decrease for all treatments. The leaf width was increased by 11.6% for KC1 and 26.2% for KC2 compared to NT. But there were no significant differences in yield, leaf length, fruit weight, fruit length, fruit width, and pericarp thickness among treatments. The contents of free sugars such as fructose and glucose were increased by microbial treatments but sucrose was not different from NT. The content of glucose in watermelon was increased by 13.8% in KC1 and 12.8% in KC2 compared to NT. The content of fructose increased by 14.6% in KC1 and by 39.8% in KC2 compared to NT. The results from the study imply that Kluyvera sp. CL-2 can be used to increase sugar content in watermelon.