• Research in Plant Disease
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• v.10 no.2
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• pp.105-111
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• 2004

Mycelial growth and days required for sclerotial formation(DRSF) in vitro, and disease incidence of infected plants in the field were investigated to evaluate disease resistance of nine garlic cultivars against two species of Sclerotium causing garlic white rot. There were differences among mycelial growth and sclerotial formation of two white rot pathogens on different garlic cultivars in vitro. Mycelial growth showed the highest level on the clove of 'Daeseo'. Sclerotia of two white rot pathogen were formed the earliest on the clove of 'Kodang' and the latest on the clove of 'Namdo'. In field trial all of nine garlic cultivars were highly susceptible to Sclerotium cepivorum and cold-type garlics were less susceptible than warm-type garlics. Meanwhile garlic cultivars used showed differences among resistant responses to Sclerotium sp., forming large sclerotia. All of warm-type garlics showed highly susceptible response, but three cold-type garlics, 'Seosan', 'Danyang' and 'Yechon' showed moderate resistant response and 'Euisung' showed resistant response. To evaluate cultivar resistance of garlics quantitatively disease progress curve was transformed as linear regression equation. Among the intercept (early disease incidence) and the slope (disease infection rate) obtained from the transformed equation, final disease incidence, and area under disease progress curve(AUDPC), AUDPC was the most effective to evaluate disease resistance of garlics to both of white rot pathogens. There was little correlation between mycelial growth and sclerotial formation on garlic cloves in vitro, and epidemiological parameters (early disease incidence, final disease incidence, disease infection rate, AUDPC) obtained from the field trial. Mycelial growth of S. cepivorum was positively correlated with final disease incidence and disease infection rate obtained from the field trial, meanwhile DRSF was negatively correlated with the epidemiological parameters.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.126-140
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• 1977

Present studies were carried out for breeding cold resistant clones of Citrus, improving overwintering techniques of Citrus in Jeju island as well as other southern region, Result obtained were as follows 1. In the vinyl house covered with two sheets of straw mat, 12 indivuals were found as non-injury and 15 were slightly injured by leaf freeging test at $-9^{\circ}C$ for 2 hours treatment. 2. In the condition of vinyl house covered with straw mat and viny film mulching and heat-in by sun-light, the inside temperature of vinyl house were not lowered below $-3^{\circ}C$ and the ground temperatura in vinyl house keeps above $0^{\circ}C$ during winter though outdoor temperature were lower by $-15^{\circ}C$(Daejeon area). 3. The vinyl tunnel inside the vinyl house and vinyl film mulching on ground position showed greater effectiveness for preventing heat loss from house but there were no significant difference between the color of vinyl film covered the tunnel. 4. In the vertical distribution of maximum temperature in vinyl house, the upper space was slightly higher than the lower position at high temperature condition, while minimum temperature was distributed as higher as the middle position, ground surface and upper position in order at low temperature condition 5. In the horizontal distribution of temperature in vinyl house, ground and surface-temperature of north side was lower than the other sides, and citrus planted within 30cm from north side wall died by cold injury and in the other side near wall appeared slight symptom of cold injury. 6. The insulating trench ($30{\times}30{\times}30cm$) packed with straw bundle installed under north wall might be effective to prevent heat loss of ground temperature. 7. In cloudy and snowy day, the temperature difference between indoor and outdoor were less, and the indoor temperature were maintained highly during night due to the effect of prevention of heat loss. 8. The highest temperature in a day was observed at about P.M. 3 both inside and outside of vinyl house and the lowest temperature was observed at about A.M. 6. The difference between the highest and lowest temperature of indoor in a sunny day was $19^{\circ}C$, compared with $9^{\circ}C$ on a cloudy or snowy day in late November. Especially, lowering of temperature in a snowy day was so less that the curve of temperature change was comparatively constant, 9. If the effective methods of citrus cultivation in vinyl house with improved clone such as hardiness. semi-dwarf and spur type are applied, it might be possible to cultivate the citrus tree safely in Jeju island as well as other southern rejion and to magnity the cultivation of citrus tree.