• Research in Plant Disease
• /
• v.17 no.2
• /
• pp.161-168
• /
• 2011

To establish simple and reliable screening method for resistant radish to Plasmodiophora brassicae Woron. using soil-drenching inoculation, the development of clubroot on radish seedlings inoculated with P. brassicae GN-1 isolate according to several conditions such as inoculum concentration, plant growth stage and incubation period after inoculation was studied. To select resistant radish against clubroot, 10-day-old seedlings were inoculated with P. brassicae by drenching the roots with the spore suspension of the pathogen to give $1{\times}10^9$ spores/pot. The inoculated seedlings were incubated in a growth chamber at $20^{\circ}C$ for 3 days then cultivated in a greenhouse ($20{\pm}5^{\circ}C$) for 6 weeks. Under the optimum conditions, 46 commercial cultivars of radish were tested for resistance to YC-1 (infecting 15 clubroot-resistant cultivars of Chinese cabbage) and GN-1 (wild type) isolates of P. brassicae. Among them, thirty-five cultivars showed resistance to both isolates and one cultivar represented susceptible response to the pathogens. On the other hand, the other cultivars showed different responses against the tested P. brassicae pathogens. The results suggest that this method is an efficient system for screening radish with resistance to clubroot.

• Research in Plant Disease
• /
• v.22 no.4
• /
• pp.249-256
• /
• 2016

To investigate the incidence of plant-parasitic nematodes from plastic-house fields of strawberry, 170 soil samples were collected from the main producing area of strawberry in Korea from 2014 to 2015. Based on the investigation, root-lesion nematode (RLN; Pratylenchus spp.) and root-knot nematode (RKN; Meloidogyne spp.) are the most important pests in plastic-house fields of strawberry with 57% and 36% incidences, respectively. Among the collected fields, 96 and 63 fields were infected RNL and RKN, respectively with 44 fields (38.8%) being detected at both nematode. High degree of incidence of both nematodes were observed in the regions of Jinju, Gyeonnam Province, Korea. For identification of species level, phylogenetic and distance analysis were performed using RLN and RKN isolates generated from the regions of Jinju. The results indicated that the RLN and RKN isolates were Pratylenchus vulnus and Meloidogyne hapla, respectively. This study showed that P. vulnus and M. hapla could be most dominant species in plastic-house fields of strawberry. This data will provide basic knowledge for development of effective control strategies.

• Geotechnical Engineering
• /
• v.12 no.2
• /
• pp.71-84
• /
• 1996

In order to investigate the influence of slanting angle of reticulated root piles(RRP) on their bearing capacities, model tests of compressive and uplift loads on RRP with different slanting angles, which were installed in sandy soils with a relative density of 47%, were carried out. Each pile which is made of a steel bar of 5mm in diameter and 300mm in length, is coated with sand to be 6.5mm in diameter. One set of RRP consists of 8 piles which are installed in circular patterns forming two concentric circles, each of which has 4 piles. Slanting angles of RRP for load tests are 0$^{\circ}$, 5$^{\circ}$, 10$^{\circ}$, 15$^{\circ}$, 20$^{\circ}$, and 25$^{\circ}$. In addition, compressive load tests on circular footing whose diameter is the same as the outer circle of RRP were carried out. Test results show that maximum load bearing capacities of RRP by regression analysis are obtained at about 12$^{\circ}$ and 13$^{\circ}$ of slanting angles for compressive and uplift load tests, respectively. Maximum compressive bearing capacity is estimated to be 13oA bigger than that of the vertical RRP and 95% bigger than that of surface footing. Maximum uplift capacity is estimated to be 21% bigger than that of the vertical RRP. And it can be appreciated that increasing the slanting angle makes the load -Settlement behavior more ductile.

• Journal of Korean Society of Forest Science
• /
• v.101 no.3
• /
• pp.443-453
• /
• 2012

The objectives of this study were to find out proper potting medium and nutrient levels in the soil to promote the root nodule formation in black locust (Robinia pseudoacacia L.) seedlings. Commercial potting medium, compost, organic fertilizer, molded forest fertilizer, and compound fertilizer were used at different mixing rates to bring in various levels of mineral nutrients in the soil. Seedlings were grown in pots in a greenhouse for three months. Commercial potting medium containing peatmoss, vermiculite, and geolite was not suited for early nodule formation due to lack of nutrients, even though it produced good total dry weight. Compost was the best medium to promote both high total dry weight production and nodule formation with providing the proper levels of nitrogen and phosphorus in the soil. Molded forest fertilizer was acceptable for nodule formation. Compound fertilizer and organic fertilizer was not suited for nodule formation. The potting medium should contain optimum levels of nitrogen (0.05-0.2%) and phosphorus (100-600ppm) to promote early nodule formation in black locust seedlings.

• Research in Plant Disease
• /
• v.23 no.2
• /
• pp.186-192
• /
• 2017

To survey the incidence of plant-parasitic nematode in strawberry nursery, 117 soil samples were collected from main producing area of strawberry nursery plants in 2016. The incidences of two major problematic nematodes such as root-lesion nematodes (Pratylenchus spp.) and root-knot nematodes (Meloidogyne spp.) were 11% and 3%, respectively. Strawberry nurseries using upland soil either in fields or in plastic-houses showed were higher infection rates of Pratylenchus spp. or Meloidogyne spp. than others. On the other hand, a strawberry nursery using pots filled with bed soil in plastic-house was the lowest infection rate with 0%. Phylogenetic relationships and distance analysis were performed for identification of Pratylenchus spp. and Meloidogyne spp. detected from strawberry nurseries. As the results, they were identified as Pratylenchus penetrans, Pratylenchus vulnus and Meloidogyne hapla. Meanwhile, when nursery plants of strawberry infested with P. vulnus transplanted to pots filled with sterilized soil, P. vulnus was detected from soil in pots as 33% frequency. Thus, P. vulnus can be spread through nursery plants of strawberry infested with that. These studies suggested that Pratylenchus spp. and Meloidogyne spp. were ploblematic nematodes in major areas of strawberry nursery plants and P. vulnus could be spread through nursery plants of strawberry.

• Korean Journal of Environmental Agriculture
• /
• v.3 no.1
• /
• pp.10-15
• /
• 1984

To get information on the behavior of phorate in vegetables under the subtropical conditions, phorate granule (10%) was applied to silt loam soil at the rate of 40㎏ a.i./ha and incorporated to 10㎝ soil depth just befere sowing. Insecticide residues in vegetables were determined with GLC and confirmed qualitatively with TLC. Phorate and its metabolites were absorbed by the radish and carrot roots and rapidly translocated into foliages. The compounds detected in vegetables were phorate, phorate sulfoxide, and phorate sulfone. Residue levels of compounds in radishes were higher in foliages than in roots and much more residues were present in leaf lamina than in midribs. The concentration of the total residues in vegetable roots was rapidly decreased with the time, while the amount of total residues in radish roots was increased with the time. Therefore, the rapid decline of residue levels in vegetables was mainly attributed to the dilution of insecticide residues by the rapid growth of these vegetables.

• Korean Journal of Soil Science and Fertilizer
• /
• v.35 no.1
• /
• pp.1-11
• /
• 2002

Root distribution was monitored in the root zone of corn fields on several soil series in central Illinois during three growing seasons in order to find the effect of soil series and tillage system on root growth. A minirhizotron technique was used to videotape each soil profile in weekly intervals to a depth of 75 cm under conventional tillage (CT) and no tillage (NT) systems of cultivation. Root distribution near soil surface generally increased during the early stages of the growing season, but declined as surface soil moisture was depleted in late summer. Even though root distribution was not significantly different between soil series in this experiment. differences in root distribution between soil series were associated with the increases in root-available water storage capacity. Root population in the top 30 cm of NT plots. where increased water infiltration rates and saturated flow of soil moisture into the subsoil, was generally higher than that of CT plots in Illinois corn fields. Foots appeared in the deeper layers later in the growing season, with root penetration into subsoil layers occurring as much as 2-3 weeks earlier on the NT plots than in CT plots. In conclusion, root distribution was significantly affected by the tillage systems, but not different by soil series.

• Food Science and Preservation
• /
• v.14 no.2
• /
• pp.170-176
• /
• 2007

In this study, extract of Ailanthus altissimawere prepared using hot water under high pressure. The extract were examined for election donating ability (EDA), superoxide dismuase (SOD)-like activity, nitrite scavenging ability (NSA), xanthine oxidase inhibition levels, and tyrosinase inhibition ability. The EDA, using the 1,1-diphenyl-2-picrylhydrazyl method of root extract was 91.25% at 1.0mg/mL. The SOD-like activity of leaf extract was highest at 49.07% and the NSA was 93.33% at pH 1.2, and 85.40% at pH 3.0. The xanthine oxidase inhibitory levels of extracts of A. altissima roots, stems, and leaves were 92.09 97.44% when the extract were tested at 2.0mg/mL. The highest tyrosinase inhibition levels obtained from loot extract were 67.38% at 2.0mg/mL and 63.97% at 0.1mg/mL.

• Research in Plant Disease
• /
• v.25 no.3
• /
• pp.124-130
• /
• 2019

The study was conducted to investigate the infestation and distribution of plant-parasitic nematodes on Chinese yam (Dioscorea batatas) in Andong, Korea. Root-knot nematodes, Meloidogyne incognita was the most prevalent nematode species which is found from 43 yam fields (81.1%) with high population densities (average of 450 juveniles/$300cm^3$). Other nematodes, root-lesion nematode (Pratylenchus spp.) and pin nematode (Paratylenchus spp.) were less problematic. Density of juveniles (J2) of M. incognita was $10\;J2/300cm^3$ by August, then increased to 274 in September and 624 in October. The highest J2 density was found at the soil depth between 40 and 50 cm ($1,840\;J2/300cm^3$). M. incognita was able to infest yam tuber down to a depth of 70 cm and developed galls outside and brown spots inside. The highest number of females were found at 40-50 cm (79 females/10 cm piece) tuber from the top.

• Journal of Korea Foundry Society
• /
• v.42 no.2
• /
• pp.83-93
• /
• 2022

Throughout this research course, we have analyzed the financial situation of more than 2,700 companies using credit evaluation disclosures from 2017 to 2019. The population was gathered based on the certification of Ppuri companies and Ppuri Expertise companies through the Korea National Ppuri Industry Center, accompanied by the NICE credit evaluation index. For the first time in Korea, we wanted to look at growth, profitability, and stability through financial analysis of the Ppuri industry. Through an indepth analysis, we identified operating income (rate), net income (rate), asset size, and debt ratio, along with three years of Ppuri company workers and total sales fluctuations, and looked at the financial structure per capita. In addition, financial status per person was compared by dividing Ppuri companies into six groups by employee size. Groups were 10 or fewer people, 11 to 20 people, 21 to 50 people, 51 to 200 people, 201-300 people, and 300 or more people; single individual companies were excluded for research convenience. Overall, the financial situation of Ppuri companies was judged to be in a very bad downturn, and financial indicators deteriorated over the course of the three years of investigation. In particular, the smaller the number of employees, the greater the financial fluctuations were and the worse the situations were. Among Ppuri companies, the casting industry, which is the technical starting point for the value chain of the industry, was found to also be in a very bad state, with continued workforce declines, total assets and sales reductions at severe levels, and operating income (rate) and net income (rate) also very poor. This is why we need a suitable and feasible policy direction, something that is difficult but must be allowed to develop.