• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.302-309
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• 1987

One hundred rice varieties were tested for their level of resistance to sheath blight disease at adult plant stage in field condition through 1984 to 1986. Rice plants were grown under ordinary seasonal culture and inoculated by k-2 fungus isolate during three years. k -1 isolate was also inoculated separately in 1984 and test under late seasonal culture was conducted in separate field in 1985. Degree of damage by the disease observed at 25 days after heading was used to identify the level of resistance of the rice varieties tested. Varietal differences of degree of damage were significant in five tests during three years, and the genotypic variance of degree of damage was always higher than environmental variance among varieties tested. Positive correlations between testing years, between cultural seasons, and between isolates inoculated were found in degree of damage of varieties tested for two or three years continuously. Degree of damage by the disease was correlated negatively with heading date of rice varieties except 1984 tests. Thus, the level of resistance should be compared among the variety group having almost same heading date in field condition, and late and extremely late variety groups should be tested for their level of resistance under appropriate environmental condition. Gayabyo, an early heading variety, and SR9713-54-3, a medium heading breeding line, showed consistent lower value of degree of damage during two or three years. These two varieties were selected as moderate resistant germplasm.

• Horticultural Science & Technology
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• v.34 no.2
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• pp.282-293
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• 2016

Root-knot nematodes (Meloidogyne spp.) are major plant pathogens that cause reductions in yield and quality of several solanaceous crops, including pepper (Capsicum spp.). These losses can be averted through planting of resistant cultivars. Plants are defined as resistant when they suppress nematode reproduction. In this study, the resistance degrees of 102 commercial cultivars of chili pepper (Capsicum annuum) to a root-knot nematode, Meloidogyne incognita, were evaluated by comparing the number of egg masses on their roots to those of 'PR huimangchan', a highly susceptible cultivar that exhibited the most egg masses of the chili pepper cultivars evaluated. Among these cultivars, forty-four (43.1%) showed resistance to M. incognita and eighteen (17.6%) were moderately resistant. The other cultivars (39.3%) were determined to be susceptible. For further study, six chili pepper cultivars (i.e., Gangryeokjosenggeon, Shinsegae, Muhanjilju, PR Bulrocho, PR Huimangchan, and Jjang) with different levels of resistance to the nematode were selected. Changes in resistance of the six cultivars under several conditions, such as inoculum concentration, plant growth stage, and cultivation period after transplanting were investigated. We found that an efficient screening method for resistance of chili pepper to M. incognita is to transplant the chili pepper seedlings 7 days before inoculation, to inoculate 28-day-old plants with M. incognita by loading 5,000 eggs per plant into the pot of soil, to cultivate the plants in a greenhouse ($25{\pm}5^{\circ}C$) for 45-60 days, to measure the number of egg masses on roots of the seedlings, and then to determine the resistance response of the plants by comparing the number of egg masses on the roots with a reference-susceptible cultivar 'PR huimangchan'.

• Korean journal of applied entomology
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• v.26 no.4 s.73
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• pp.245-249
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• 1987

In the 82 apple varieties tested, the distribution of varieties grouped on the damage degree to Alternaria leaf spot were 15 varieties(l8.3%), which damaged above 50%, and 51 varieties(62.2%) damaged below 5%. Susceptible varieties to Alternaria leaf spot were Raritan, Indo, Winesap and Starkrimson, moderately resistant varieties Sekaiichi and Starking, and resistant Jonathan, Tsugaru, Molliies, Jonagold, Gala etc. The leaf hair density on the backside of leaf were rarer inresistant varieties than susceptible one. In inoculation test, penetration and infection of Alternaria mali were easier on the backside than surface of apple leaf at the same varity, and infection rate with Alternaria mali were higher at removal treatment than non-removal one of leaf hairs, so we can guess that leaf hair are related to resistance of variety to Alternaria mali.

• Horticultural Science & Technology
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• v.31 no.3
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• pp.366-370
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• 2013

This experiment was carried out to establish the screening methods for the selection of Zantedeschia aethiopica cultivars resistant to calla lily soft rot caused by Pectobacterium carotovorum subsp. carotovorum. A center of leaf and petiole tissues of four Z. aethiopica cultivars were wounded and inoculated with three different inoculum concentrations, $1{\times}10^7cfu/mL$, $1{\times}10^8cfu/mL$, and $1{\times}10^9cfu/mL$, of EccNHRI-21 isolate. And they were evaluated at 4, 18, and 26 hours after inoculation. The lesion of maceration was developed well in the leaf tissues inoculated with $1{\times}10^9cfu/mL$ concentration. And evaluation of resistance in 18 hours after inoculation was correlated with field resistance positively. Using this method, ten Z. aethiopica commercial cultivars and four wild types were screened. 'Crowbrough' and 'White Cutie' were selected as highly resistant genotypes and 'Mont Blanc' and 'Silky White' as resistant genotypes. 'Wedding March' and 'Kiwi Blush' were evaluated as moderate resistant and the others including 'Childsiana' were susceptible. And all of four wild types were evaluated as more than moderate resistant. In spite of control through cultural, biological and chemical methods, the use of resistant cultivars is most efficient to overcome calla lily soft rot. This newly developed screening method was helpful for breeding new varieties resistant to calla lily soft rot.

• Korean journal of applied entomology
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• v.11 no.2
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• pp.55-60
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• 1972

The study has been carried to investigate the nature of resistance in rice varieties against bacterial leaf blight caused by Xanthomonas oryzae (Uyeda et. Ishiyama) Dowson. In this study, differences on several morphological histological and bacterial growth in rice leaf extract from different varieties were examined. Shirogane and Norm 6 as resistant varieties, Paldal as moderately resistant, and Jinheung, Kimmaze and Suwon 213 as susceptible varieties were used throughout the experiment. 1. Susceptible varieties Jinheung, Kimmaze have more hydathods in flag leaf than resistant varieties but there were no difference between resistant varieties and moderatly resistant varieties. 2. Average length of xylem vessel elements were 50r longer in leaf veins of susceptible varieties Jinheung, Kimnaze and Suwon 213 than those of resistant varieties, but there were no difference among Paldal, Norm 6 and Shirogane. 3. Kimmaze and Suwon 213 have larger diameter of xylem vessel elements than those of other varieties examined. However, it did not differ significantly between resistant varieries and susceptible varieties statistically. 4. Jinheung and Kimmaze have more secondary xylem vessels in root of 6-7th leaf stage than those of Shirogane and Norm 6. Suwon 213, however, showed least number of secondary xylem vessels exceptionally. 5. Leaf extract from resistnat variety Shirogane, suppressed bacterial growth significantly when compared with those from other varieties. 6. Bacterial growth in autoclaved leaf extract from resistant varieties and susceptible varieties did not show any noticeable difference. In general, fresh extract maintained more bacteria than in autoclaved extract after 48 hours of incubation period.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.3
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• pp.203-208
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• 1984

This study was investigated to know the possible linkage relationship between blast resistance gene and plant height gene in rice. Two resistant varieties, Tadukan and Tetep were crossed with six susceptible semi-dwarf tester lines. Progenies derived from the crosses were inoculated with spray method at 3-4 leaf stage with blast races, C-8$^{+t}$ and T-2$^{+t}$. The results indicated that: (1) Resistance of Tadukan and Tetep to the C-8$^{+t}$ was controlled by a single dominant gene, respectively. (2) Resistance of Tadukan and Tetep to the T-2$^{+t}$ was expressed by complementary gene action between two dominant genes, respectively. (3) No linkage relationship was found between resistance gene and plant height gene of both Tadukan and Tetep when tested with C-8$^{+t}$ and T-2$^{+t}$, respectively.espectively.

• Korean journal of applied entomology
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• v.40 no.2
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• pp.143-147
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• 2001

Nineteen pepper (Capsicum annuum L.) cultivars were screened for the resistance to two common species of root-knot nematodes, Meloidogyne incognita and M. arenaria. The tested pepper cultivars showed different degrees of resistance to M. incognita but all were resistant to M. arenaria. The cultivars cv. Gonggongchil, Green No. 500 Pimento, Dahonggeon, Manitta, Shinbaram, Perfecto, and Hanmaeum were resistant to the both species of root-knot nematodes. Therefore, seven selected resistant pepper cultivars are recommended as resistant rotation crops in greenhouses where root-knot nematodes are problematic.

• Current Research on Agriculture and Life Sciences
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• v.32 no.3
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• pp.111-117
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• 2014

Phytophthora blight caused by Phytophthora capsici Leonian is a dangerous disease threatening pepper growers worldwide. The efficacy of chemical control is generally low as the pathogen is soil-borne and rapidly spread by zoospores during the rainy season. Thus, based on the demand for resistant varieties, various good resistant sources, such as CM334, AC2258, and PI201234, have been reported and their inheritance of resistance studied by many different authorities. However, the mode of inheritance remains unclear, as 1 or 2 independent dominant genes, 3 genes, or multiple genes have all been reported as responsible for resistance. Recently, QTL mappings of the gene factors for resistance have been reported, and molecular markers for resistance used in breeding programs. With the release of many resistant commercial hybrid cultivars, differentiation of pathotypes of the pathogen is attracting interest among breeders and plant pathologists. Various authorities have already classified the pathogen strains into different races according to the inter-action between resistant host plants, including the source of resistance, such as CM334 and PI201234, and resistant commercial varieties and P. capsici isolates. However, no standard differential host sets have yet been established, so the results are good only for the pathogen strains used in the experiments. Thus, for breeding varieties with durable resist-ance, it is important to introduce resistance from different sources and use diverse local pathogen strains collected in the target area for distribution in a breeding program.

• Korean journal of applied entomology
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• v.26 no.4 s.73
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• pp.257-259
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• 1987

One thirty one varieties of Groundnut were screened for search of multiple disease resistance against rust caused by Puccinia arachidis speg. and leaf spots caused by Cereospora arachidis Hori and Phaeoisariopsis personata . Out of these, 7 were resistant, and 11 were moderatly resistant. Percent disease severity and its' effect on yield was assessed.

• Korean journal of applied entomology
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• v.38 no.3
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• pp.249-253
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• 1999

To study races of Heterodera glycines in Korea, 21 soil samples were collected from eight provinces in 1995. Four races were found; race 3(48%) was a dominant race flowed by race 5(24%), race 1(19%), and race 6(9%). About 30~40% of H. glycines populations reproduced on Pickett and PI88788, while non reproduced on Peking or PI90763. Development of resistant soybean cultivar targeting to race 5 and 6 of H. glycines using PI90763 and PI88788 as a parent is recommended.