• Research in Plant Disease
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• v.22 no.3
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• pp.133-144
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• 2016

Powdery mildew (Podosphaera xanthii) causes severe damage to pumpkin crops grown in open fields and plastic house. Initially, we used ten accessions of pumpkin species; Cucurbita pepo (3), C. maxima (2), C. moschata (2), and C. argyrosperma (3) to study the disease progress in different stages of seedling development. Commercial pumpkin varieties were used as susceptible host for inoculum management and young seedlings were inoculated by dusting powdery mildew spores on the cotyledons, 1-true-leaf and 2-true-leaf seedling stages. Based on initial study, we further evaluated 218 pumpkinaccessions for their resistance to powdery mildew in different seedling stages under plastic house. Area under disease progress curve (AUDPC) and relative AUDPC (rAUDPC) was higher in cotyledonary and 1-true-leaf than 2-true-leaf stage. Seedlings at cotyledons and 1-true-leaf seedling stage displayed more susceptibility to powdery mildew. Based on evaluation of 2-true-leaf stage, IT 110859 and IT 278459 from C. pepo and C. argyrosperma identified as resistant (<0.2). Of the 228 pumpkin accessions, 21 (9.2%) pumpkin accessions consisting of C. pepo (2), C. maxima (5), C. moschata (13), and C. argyrosperma (1) exhibited intermediate resistance (<0.4) to powdery mildew and these accessions are useful to growers for its rational management.

• Korean Journal of Environmental Agriculture
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• v.34 no.3
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• pp.186-191
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• 2015

BACKGROUND: Carotenoids which are a major source of vitamin A are contributed to have great potential role in anti-carcinogenic effects and eyesight. Carotenoids which can not synthesize in human body are required for food supply. The objectives of this study are to investigate compositions and contents of pumpkin (Cucurbita spp.) germplasms based on their pulp color. METHODS AND RESULTS: Carotenoids were extracted with 0.2% ascorbic acid in ethanol and saponified with 80% potassium hydroxide. Insoluble compounds were extracted into hexane. A total of nine carotenoids (three xanthophylls and six carotenes) were identified from pumpkin germplasms using HPLC equipped with photodiode array detector (450 nm). Especially, lutein and ${\beta}$-carotenes were major compound in germplasms. Among isomers of ${\beta}$-carotene, all-trans-${\beta}$-carotene (16-27% of total carotenoids) was predominant compositions. The mean of total carotenoid contents was showed as brown (286.1 mg/100 g dw) > dark green (217.0) > orange (153.4) > primrose (85.8) > dark yellow (80.3). On the basis of carotenoid information, PLS-DA score plots showed different patterns by cluster in pumpkin germplasms. It was considered that these differences of phenotype were relative closely to genotype. CONCLUSION: This study indicated that dark color of pumpkin pulp was presented in high-level of biological pigments. It may contribute to develop potentially beneficial functional food ingredients.