• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.419-429
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• 2017

We investigated the occurrence pattern of diseases and insect pests and disease control efficacy of organic materials against watermelon powdery mildew in small type watermelon in Eumseong, Chungcheongbuk-do, 2015. The result of this study, the small type watermelon was damaged by diseases and pests such as Didymella bryoniae, Podosphaera xanthii, Aphis gossypii, Tetranychus urticae, thrips, Spodoptera exigua and Spodoptera litura. Among them, the occurrence of P. xanthii, T. urticae and thrips was high. Diseased leaf rate by P. xanthii, a casual agent of powdery mildew, was 27~99.3% in three small type watermelon cultivars in the middle of June. The number of T. urticae per leaf was high from 79.9 to 111 in three small type watermelon cultivars in the middle of June. It showed high number of thrips captured by yellow and blue sticky trap. Highest numbers of yellow sticky trap (407) and of blue sticky trap (774) were detected in the middle and first of June, respectively. The disease control efficacy of mayonnaise, oleic acid and three organic materials against powdery mildew of small type watermelon in fields was evaluated. As thre results, the symptoms of plant disease were effectively reduced by over 60% in the treatments of materials such as sodium bicarbonate 80%, mayonnaise and the extract of Rheum palmatum 1%. The highest control efficacy was 83% in the treatment of sodium bicarbonate 80%. From this study, we had a information of the occurrence pattern of diseases and insect pests in small type watermelon and the treatment of material containing sodium bicarbonate 80% was very effective for controlling against powdery mildew.

• Animal cells and systems
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• v.14 no.3
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• pp.225-236
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• 2010

We compared the composition of phospholipid fatty acids (PLFA) to assess the microbial community structure in the soil and rhizosphere community of non-transgenic watermelons and transgenic watermelons in Miryang farmlands in Korea during the spring and summer of 2005. The PLFA data were seasonally examined for the number of PLFA to determine whether there is any difference in the microbial community in soils from two types of watermelons, non-transgenic and transgenic. We identified 78 PLFAs from the rhizosphere samples of the two types of watermelons. We found eight different PLFAs for the type of plants and sixteen PLFAs for the interaction of plant type and season. The PLFA data were analyzed by analysis of variance separated by plant type (P<0.0085), season (P<0.0154), and the plant type${\times}$season interaction (P<0.1595). Non-parametric multidimensional scaling (NMS showed a small apparent difference but multi-response permutation procedures (MRPP) confirmed that there was no difference in microbial community structure for soils of both plant types. Conclusively, there was no significant adverse effect of transgenic watermelon on bacterial and fungal relative abundance as measured by PLFA. We could reject our hypothesis that there might be an adverse effect from transgenic watermelon with our statistical results. Therefore, we can suggest the use of this PLFA methodology to examine the adverse effects of transgenic plants on the soil microbial community.

• 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.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.189-195
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• 2020

This research was carried out to find the proper number of stem training and position of fruit setting that can be stably produced for the cultivation in small and medium types of watermelon during winter. The treatments for the number of stem training were 2-, 3-, 4-stems, respectively. Growth characteristics (plant height, stem diameter, no. of node, etc.) by number of stem training were higher in 2-stem than in 3-4-stem. However, Fruit characteristics such as weight, length, width were high in the 4-stem. There is no significant difference between the soluble solids and fruit setting rate depending on the stem training. The position of fruit setting were three points: 2nd, 3rd, 4th female flower positions. The fruit setting is one fruit per plant. The average fruit setting nodes of 2^nd, 3^rd and 4^th female flowers were 11.5, 15.8 and 23.1 nodes, respectively. The 4^th female flower was 0.8 kg heavier than 2^nd female flower because of its increased weight as position of fruit setting was higher. However, the soluble solids decreased as the position of fruit setting increased, with the second female flower being 1.3°Bx higher than the 4^th female flower. The Fruit setting rate was no significant difference. Considering the growth and fruit characteristics, it is believed that the small and medium-sized watermelon in winter will have a high quality production of watermelon when the stem training is 3-stem and the position of fruit setting is 3^rd female flower. However, it is thought that additional studies are needed to stabilize the income of watermelon-growing farms, such as planting distance and adhesion of small and medium-sized varieties.

• Horticultural Science & Technology
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• v.17 no.6
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• pp.737-741
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• 1999

We surveyed the physiological disorders of fruit vegetables grown in the greenhouse in Kyungbuk province in 1998. Greenhouses used for cultivation were mostly single or multi-span iron pipe houses covered with polyethylene film. Single span greenhouses were used for strawberry, oriental melon and watermelon. Fifty six percent of the surveyed farms was a mono-cropping system for oriental melon and tomato. There were greenhouses used for successive cultivation for 10 years or more for strawberry and oriental melon in Koryeong and Seongju. Varieties of fruit vegetables cultivated were diverse, especially in cucumber and watermelon. In strawberry, malformed fruits were observed most frequently in March and the small fruits at late harvest period. Leaf chlorosis, stunt plants and runner outbreak were also found during the growing season. In tomato, occurrence of malformed fruits was severe from March to May, and occurrence of cracked fruits and blossom- end rot was also severe in October and November. The self topping and abnormal stem in tomato were problem in hydroponic cultures in August and November, respectively. Malformed cucumber fruits, such as curved, club shaped, irregular shaped and narrow necked, occurred at late season. Umbrella-shaped leaf in cucumber in summer were caused by calcium deficiency. Most serious disorders were fermented and malformed fruits occurring from March to May in oriental melon, and cracked fruits occurring from April to May in watermelon. At late growing stage of melons the leaf chlorosis occurred with complex symptoms of leaf disease. Growers had little knowledge on physiological disorders, and also on diagnose and measures to cure the disorders. Most growers pointed out that poor soil environment and temperature management in the greenhouse as the main causes of physiological disorders.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.403-411
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• 2009

We inspected seed sizes of 353 genetic accessions of watermelon to diversify functional utility related to seed size and classified them into six representative groups based on their seed sizes. Each group was named as giant seed (GS), big seed (BS), medium size (NS), small size (SS), micro seed (MS) and tomato seed (TS) from the biggest. As the seed size was getting smaller, decreased seed length and seed width, increased seed number per fruit, and decreased seed weight per fruit were observed, but seed shape did not change significantly. In order to study the effect of seed size on fruit weight and seed germination, we developed three near isogenic lines (NILs) with three different seed sizes, SS, MS and TS, from crossing between two accessions 'NT' and 'TDR', and one NIL with seed size of TS from crossing between two accessions 'S55' and 'TDR'. In the study on the fruit weight of NILs with various seed sizes, NS, SS, MS, and TS NILs produced an average of 6.4, 6.3, 5.9, and 4.2 kg fruits, respectively. The bigger seed types showed the better germination rate. NS type showed the highest germination percentage, while TS showed very low germination percentage. Fermentation treatment for 48 hrs increased the germination percentage on TS type seed, but still remained at a low level. In NS, SS, and MS material, the ratio of embryo/whole seed weight was over 50%, meanwhile that of TS was only 44.4% of which low embryo percentage would be one of the reason of low germination percentage. From this study, we concluded that watermelon has very wide genetic diversity on seed size which is somehow related to fruit sizes and germination rate.