미치는 영향을 조사하기 위하여, 중금속이 오염된 토양에 토마토를 심고, 뿌리 혹선충의 알을 접종한 후 토마토의 생육상과 뿌리혹선충의 밀도를 조사하였다. 실 험에 사용된 토양은 Cd은 3.0~10.6(mg/kg), Pb은 128.6~339.0(mg/kg), Zn은 123.7~262.19(mg/kg)이 농축되어 있으며, 농경지의 중금속 기준 농축량 높았다. 중금속이 오염된 토마토 지상부의 평균 높이와 무게는 각각 19.5cm와 3.6g 이었으 며, 중금속이 오염되지 않은 토양에서 자란 토마토의 평균 키와 무게는 51.9cm와 12.5g이었다. 토마토의 키는 신뢰한계 99%에서 통계적으로 유의성을 보였으나, 무게는 편차가 커서 유의성을 보이지 않았다. 중금속이 오염된 토양에서 자란 토 마토 뿌리의 평균 길이와 무게는 각각 5.9cm와 4.3g이었으며, 오염되지 않은 토양 에서 자란 토마토 뿌리의 평균 길이와 무게는 각각 15.0cm와 8.1g이었다. 뿌리의 길이는 99% 신뢰수준에서 통계적으로 유의성을 보였으나, 무게는 유의성이 없었 다. 뿌리혹선충에 의한 토마토 뿌리의 gall index는 오염토양이 1.3이었으며, 오염 되지 않은 토양의 gall index는 4.3으로 오염되지 않은 토양에서 자란 토마토가 뿌 리혹선충의 혹이 더욱 많았으며, 통계적으로 차이를 보였다. 선충의 밀도는 유의 성이 없었다. 중금속이 토양내에서 농도가 높을 수록 토마토의 생육과는 음의 상 관관계를 보이며, 특히 Pb은 상관계수가 -0.62로 높았다. 또한 식물기생선충인 뿌 리혹선충(Meloidogyne incognita)에 의한 혹형성과 토양내 중금속의 농도에 대한 상관계수도 -0.62로 높았다. 중금속이 토양내 고농도로 축적되어 있으면, 토마토 의 생육에 영향을 주고, 생육중 시들음 증상이 증가하며, 식물기생선충인 뿌리혹 선충의 활동에도 영향을 주는 것으로 조사되었다.

This study was conducted to identify plant-parasitic nematodes and determine the distribution pattern of the nematode species in citrus fruit orchards in Korea from April to August, 2008. Plant-parasitic nematodes were found in 139 among 178 soil samples. Tylenchulus semipenetrans was collected from 85 out of 94 Citrus unshiu orchards examined (90.4%). C. junos orchards infested with T. semipenetrans were 60 out of 84 (71.4%). However, proportion of dominant species between the two was different. At domestic Citrus orchards, it proved that T. semipenetrans was the most important plant-parasitic nematode from this study. The overall frequency of the plant-parasitic nematodes was positively correlated with the cultivation years. More alkaline soils tended to harbor more T. semipenetrans. However the correlation coefficient between the two was very low.

Root-lesion nematode (Pratylenchus vulnus) and pin nematode (Paratylenchus sp.) were detected with high population density at the spray chrysanthemum greenhouse in Gumi, Gyeongbuk. The average density of P. vulnus and Paratylenchus sp. was 667 and 716 nematodes per 100 g soil and P. vulnus density were distributed 87% to the depth of 0~30 ㎝ in greenhouse. When spray chrysanthemum cv Chopin, was transplanted in September 2004 in greenhouse, P. vulnus were 854 nematodes/100 g soil in planting and increased 14,985 nematodes/100 g soils and 1g root after 10 weeks in harvest. Shoot weight and shoot height of spray chrysanthemum decreased 24.8% and 8.0% compared with non-infested P. vulnus after 10 weeks in greenhouse.

A survey was conducted to find out the major plant parasitic nematode in Chrysanthemum morifolium fields in Korea from May to June in 2005. A genus of Pratylenchus was determined as the most important plant parasitic nematode based on analysis of total 50 samples from 8 cities of chrysanthemum field. Pratylenchus showed 86% occurrence rate and average numbered 1,095 per 200㏄ soils and Ig root. Five Pratylenchus isolates, "Muan", "Masan", "Tean", "Gumi", "Jeongup", were selected for the molecular identification of the species of Pratylenchus, and ITS and D3-28S ribosomal DNA were amplified by PCR. For the ITS, only" Muan" isolate was differentiated by total 1 kb PCR amplification, which was 200 bp larger than all the other isolates. There was no size variation in amplified D3-28S rDNA and all isolate represented approximately 320 bp of PCR product. Sequence data of D3-28S rDNA were analysed by MegAlign program in DNASTAR software and phylogenetic tree was constructed. Sequence homology was 100% between "Gumi" isolate and "Tean" isolate and "Jeongup" isolate was also close to these isolates by 99.7% sequence homology. "Gumi", "Tean" group and "Jeongup" isolate were determined to be closely related to Pratylenchus vulnus by 96.7% and 96.3% similarity in respectively. D3 sequence of "Masan" isolate was 100% identical to P. penetrans, and "Muari" isolate showed 99.7% similarity to P. brachyurus. This result was congruent with the branch divergence pattern shown in phylogenetic tree.

Total of 36 sweet potato field soils were sampled to survey the occurrence of the root-knot nematodes (RKN). The 61% of sweet potato fields in Haenam, 40% in Iksan and 31% in Yeju were infested with RKN, respectively. Average population density of RKN was 324 juveniles per 300 g soil. The resistance screening of sweet potato cultivars against RKN was carried out by using clay pots in a greenhouse. Average temperature under ground 10 ㎝ in pot was 21.5℃ during the test. There was no difference in number of egg sacs among different inoculation methods, however the egg-inoculation method was easy for treatment and had stable for results. The multiplication ratio of Melioidogyne incognita differed from 6.3 times (Jeungmi) to 63.2 times (Yulmi) by sweet potato cultivars. There were no cultivars showing resistance to M. incognita, but Jinmi, Jeungmi and Borami had resistance to M. arenaria, M. hapla and M. javanica.

This study was conducted to develop a predictive model for the growth of Escherichia coli strain RC-4-D isolated from red kohlrabi sprout seeds. We collected E. coli kinetic growth data during red kohlrabi seed sprouting under isothermal conditions (10, 15, 20, 25, and 30°C). Baranyi model was used as a primary order model for growth data. The maximum growth rate (μmax) and lag-phase duration (LPD) for each temperature (except for 10°C LPD) were determined. Three kinds of secondary models (suboptimal Ratkowsky square-root, Huang model, and Arrhenius-type model) were compared to elucidate the influence of temperature on E. coli growth rate. The model performance measures for three secondary models showed that the suboptimal Huang square-root model was more suitable in the accuracy (1.223) and the suboptimal Ratkowsky square-root model was less in the bias (0.999), respectively. Among three secondary order model used in this study, the suboptimal Ratkowsky square-root model showed best fit for the secondary model for describing the effect of temperature. This model can be utilized to predict E. coli behavior in red kohlrabi sprout production and to conduct microbial risk assessments.