• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.312-317
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• 2013

Purpose: Conventional methods used to evaluate seeds viability are destructive, time consuming, and require the use of chemicals, which are not feasible to implement to process plant in seed industry. In this study, the effectiveness of Fourier transform near infrared (FT-NIR) spectroscopy to differentiate between viable and nonviable watermelon seeds was investigated. Methods: FT-NIR reflectance spectra of both viable and non-viable (aging) seeds were collected in the range of 4,000 - 10,000 $cm^{-1}$ (1,000 - 2,500 nm). To differentiate between viable and non-viable seeds, a multivariate classification model was developed with partial least square discrimination analysis (PLS-DA). Results: The calibration and validation set derived from the PLS-DA model classified viable and non-viable seeds with 100% accuracy. The beta coefficient of PLS-DA, which represented spectral difference between viable and non-viable seeds, showed that change in the chemical component of the seed membrane (such as lipids and proteins) might be responsible for the germination ability of the seeds. Conclusions: The results demonstrate the possibility of using FT-NIR spectroscopy to separate seeds based on viability, which could be used in the development of an online sorting technique.

• Korean journal of applied entomology
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• v.42 no.2
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• pp.119-124
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• 2003

The adult of the Cotton caterpillar, Palpita indica (Saunder) laid eggs more on mature leaves than on aged and developing leaves. They laid more on leaves than on petiole and stem, and more on the adaxial than on the abaxial surface side of the leaves. Larvae of the Cotton caterpillar showed their preference in the order of the cucumber (Cucumis sativus), gourd (Lagernaria siceraria), watermelon (Citrullus lanatus) ＞ oriental melon (Cucumis melon L. var makuwa), wax gourd (Benincasa hispida), melon (Cucumis melo), star cucumber (Sicyos angulatus) ＞ sponge cucumber (Lufa cylindrica), cotton (Gossypium indicum). There were no distinct differences among varieties and lines that were collected and hybridized at the Gochang Watermelon Experiment Station in Korea. There was a positive relationship between the leaf area and the degree of damage by the Cotton caterpillar. The feeding amounts of the Cotton caterpillar excrement were gradually increased to 16-18 days after hatching, after that the amounts of excrement were rapidly decreased.

• 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.

• International Journal of Industrial Entomology and Biomaterials
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• v.37 no.2
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• pp.109-116
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• 2018

We investigated the effects of honey bee (Apis mellifera L.) colony size on the pollination of greenhouse-cultivated watermelon grown under the forcing cultivation system. The highest pollination activity of bees was observed ($14.3{\pm}5.0$ honey bees/day) when the bee colony size was 10,000 followed by 7,500 and 5,000 honey bees. There was a positive correlation between the bee colony size and pollination activity (R = 0.262) but insignificant difference in fruit set with different honey bee colony sizes (88%-91%). Evaluation of physical properties revealed that the weight and shape of watermelon were also not significantly different among different colony sizes. However, larger the bee colony size, higher the number of seeds were fertilized and rate of seed fertilization (p > 0.05). Number of seeds and content of sugar were negatively correlated (R = -0.714). Fertilized seeds showed a significant increase in mealy flesh, which has a negative effect on fruit quality, compared with that of the unfertilized seeds. Overall, we found that a colony size of 5,000 honey bees was the most effective for the pollination of watermelon grown under forcing cultivation. A comparison of the effects of bee pollination with those of artificial pollination suggested that artificial pollination can be effectively replaced by bee pollination in the forcing cultivation of watermelon, because fruit set, weight, and shape by bee pollination were similar to those achieved by artificial pollination.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.32-32
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• 2020

High-quality and high-phytonutrient watermelon fruits have strong market opportunities besides their health related benefits. Hence, investigating quality and nutritional related traits of watermelon genetic resources could provide important baseline data in breeding for increased lycopene content thereby increasing the marketability of watermelon. To this end, we have examined some fruit morphological traits and lycopene content of 105 genetic resources. The morphological characters were recorded on the field and inside laboratory and lycopene was measured using spectrophotometric and HPLC methods. Watermelon fruits have shown a diverse morphological characters. Red and pink fleshed fruits dominated in the entire collections. Fruits with higher thickness of rind were found to exhibit less soluble solid content (SSC). Korean origin fruits were characterized by intermediate SSC while USA, RUS, TJK, TKM, TWN, and URY originated fruits had the highest SSC. The lycopene content varied between 41.37 and 182.82 ㎍/g, 2.81 and 163.72 ㎍/g, and 3.54 and 255.47 ㎍/g using HPLC, UV-Vis, and microplate reader instrumnets, respectively. Red- and pink-fleshed fruits had the highest levels of lycopene content compared to the yellow- and orange-fleshed. Lycopene content had a significant positive correlation with SSC, however, no correlations were detected between lycopene and other quantitative fruit morphological characters.

• Food Science and Preservation
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• v.22 no.2
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• pp.159-166
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• 2015

This study was carried out to compare the storage characteristics of watermelon (Citrullus lanatus) before and after removing the T-shaped stalk. For the investigation of the physiochemical properties of the watermelo, the watermelaon was stored at room temperature and $7^{\circ}C$, respectively. The average weight of the watermelon (7.8 kg) decreased by 0.6~0.7% at $7^{\circ}C$ and by 1.9~2% at room temperature during the storage period of 30 days. The hardness of watermelon reduced from 755 g to 542~549 g at room temperature for 30 days. However, the existence of T-shape stalk did not significantly affect on their weight and hardness. In addition, the pH, total acid content, and inner moisture of the watermelon were not significantly changed during the storage periods while the soluble solid at room temperature was significantly decreased from $11.3^{\circ}Brix$ to $9.3^{\circ}Brix$ after 30 days of storage. The internal redness of the watermelon decreased from 36.7 to 31.7~33.6. The total amount of its free sugar was increased from the original amount (8,133 mg/100 g) and then decreased. However, the stalk did not significantly affect on the amount of total free sugar under the same storage condition, too. Thus, there was no significant difference between the results of leaving the T-shaped stalk and removing it after harvesting the watermelon.

• Research in Plant Disease
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• v.20 no.1
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• pp.31-36
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• 2014

Alternative spraying was developed using fungicides and potassium phosphonate to control watermelon powdery mildew (WPM) caused by Sphaerotheca fusca under greenhouse condition. In 2010 trial, a total of 9 combinations of 6 fungicides which are legally registered in Korea and currently used on watermelon farms were tested for the control efficacy against WPM. Though the combination of chlorothalonil (Chl)-myclobutanil (My)-fenarimol (Fen)-hexaconazole (Hex) was the most effective (82.6%) in the first-year trial, it had the problem that My, Fen and Hex have the same mode of action. Therefore, in the second-year trial to improve the fungicide combination and to reduce fungicide application, fungicides and potassium phosphonate (P) combinations were tested for WPM control using 500 ppm aqueous potassium phosphonate solution which is both eco-friendly and showing different mode of action from the fungicides tested. The P-My-Fen-Hex applied at 10-day intervals provided relatively high control (75.6%), whereas Chl-My-Fen-P provided 31.8% control. To improve the control, fungicides and P were applied at 7-day intervals in the third-year trial. Though Chl-My-Fen-Hex provided the highest control (89.6%), P-My-Fen-Hex also provided relatively high control (83.5%) compared to 65.9 % control with Chl-My-Fen-P, which suggests that Chl-My-Fen-Hex could be replaced with P-My-Fen-Hex for WPM control.

• Journal of Bio-Environment Control
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• v.19 no.2
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• pp.82-87
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• 2010

To investigate effects of kind of pot for raising of seedling (single plastic pot, double plastic pot, circular peat pot, square peat pot) and planting method of the pot (3/3, 2/3, and 1/3 by the buried degree of pot height) on watermelon (Citrullus lanatus) growth, this research was conducted under plastic film house. Since planting of seedlings, number, area and photosynthesis rate of leaves, plant height and weight were superior in seedling grown in double plastic pot than those grown in the others. In fruit characteristics harvested at 12 weeks after planting, fruit height, diameter and weight were longer in double plastic pot than in the others, also fruit peel thickness and hilum diameter were thicker and shorter. Initial growth of the plant after planting with seedling grown in double plastic pot was superior in method buried the 2/3 degree of the pot height than the other methods.

• Horticultural Science & Technology
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• v.34 no.6
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• pp.912-923
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• 2016

Watermelon production is often limited by powdery mildew in areas with a large daily temperature range. Development of resistant watermelon cultivars can protect against powdery mildew; however, little is known about the characteristics of its causal agents. Here, we identified the genus and race of a causal pathogen of powdery mildew in Ansung province of South Korea, and developed molecular markers for the generation of resistant watermelon cultivars. The causal pathogen was determined to be Podosphaera xanthii based on multiple sequence alignments of internal transcribed spacers (ITS) of rDNA. The physiological race was identified as 1W, and the Ansung isolate was named P. xanthii 1W-AN. Following inoculation with the identified P. xanthii 1W-AN, we found inheritance of the resistant gene fitting a single dominant Mendelian model in a segregated population ('SBA' ${\times}$ PI 254744). To develop molecular markers linked to fungus-resistant loci, random amplified polymorphic DNA (RAPD) was accomplished between DNA pooled from eight near-isogenic lines (NILs; $BC_4F_6$), originated from PI 254744 and susceptible 'SBB' watermelon. After sequencing bands from RAPD were identified in all eight NILs and PI254744, 42 sequence-characterized amplifiedregion (SCAR) markers were developed. Overall, 107 $F_2$ plants derived from $BC_4F_6$ NIL-1 ${\times}$ 'SBB' were tested, and one SCAR marker was selected. Sequence comparison between the SCAR marker and the reference watermelon genome identified three Nco I restriction enzyme sites harboring a single nucleotide polymorphism, and codominant cleavage-amplified polymorphic site markers were subsequently developed. A CAPS marker was converted to a high-resolution melt (HRM) marker, which can discriminate C/T SNP (254PMR-HRM3). The 254PMR-HRM3 marker was evaluated in 138 $F_{2:3}$ plants of a segregating population ('SBA' ${\times}$ PI254744) and was presumed to be 4.3 cM from the resistance locus. These results could ensure P. xanthii 1W-AN resistance in watermelon germplasm and aid watermelon cultivar development in marker-assist breeding programs.

• Korean Journal of Plant Resources
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• v.28 no.5
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• pp.656-664
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• 2015

To produce high quality watermelon, three tetraploid watermelon breeding lines (‘SA03-1’, ‘SA06-1’ and ‘SB01-1’) were developed by treatment with different chromosome doubling reagents. To identify the optimal tetraploid inductive conditions, the three watermelon breeding lines were selected by counting the number of doubled chloroplasts in guard cells. Tetraploid induction rates differed depending on the genotypes and treatment with doubling reagents. However, the highest induction rate occurred with 1.0% colchicine (82.2%). These putative tetraploid lines were re-confirmed for ploidy using flow cytometric analysis and chromosome counting. The internode length of the tetraploid breeding lines was different when the leaf size was larger in all three tetraploid lines compared to their diploids. The fruit weight of the tetraploid fruits for ‘SA03-1’ and ‘SB01-1’ was lower than for their diploid, and the rind thickness and total sugar content (°Brix) of tetraploid SB01-1 were significantly different from those of its diploid. Tetraploid lines were sterile, yielded a lower number of seeds per fruit for ‘SA03-1’ (21), ‘SA06-1’ (62), and ‘SB01-1’ (34.7), and the seeds were larger and thicker than those of their diploids. These tetraploid breeding results will be useful for breeding new seedless watermelon cultivars.