• Korean Journal of Weed Science
• /
• v.6 no.2
• /
• pp.168-173
• /
• 1986

The effects of varying concentrations and duration of fluazifop-butyl [(${\pm}$)-butyl [2- [4- [(5-(trifluoro methyl)-2-pyridinyl] oxy] phenoxy] propanate] treatment on cell division, cell enlargement, and protein synthesis were studied. Oat (Avena staiva L.) were treated from 0 to 48 hr with concentration ranging from $1{\times}10^{-6}M$ to $1{\times}10^{-3}M$ of fluazifop-butyl in the cell division study. There was a significant reduction in the mitotic indices of oat roots treated with $1{\times}10^{-4}M$ after 6 hr. After 18 hr treatment, All herbicide treatment inhibited cell division significantly. After 24 hr treatment almost 100% inhibition of cell division occurred at $1{\times}10^{-4}M$ to $1{\times}10^{-3}M$ while 20% inhibition of cell division occurred at $1{\times}10^{-6}M$ concentration at same exposure period. The greatest inhibition of cell division occurred between 0 to 18 hr. The avena coleoptile straight- growth test were used to determine the influence of fluazifop-butyl on eoleoptile growth. Significant inhibition of elongation of oat coleoptiles were observed at $1{\times}10^{-7}M$ to $1{\times}10^{-3}M$ after 24 hr incubation. Protein incorporation study showed that the $1{\times}10^{-4}M$ of fluazifop-butyl caused 60% inhibition of protein synthesis. It was concluded that the growth of inhibition of plants caused by fluazifop-butyl results from inhibition of cell division, cell enlargement, and protein synthesis.

• Research in Plant Disease
• /
• v.10 no.4
• /
• pp.290-296
• /
• 2004

Bacterial blossom blight is one of the most important diseases of kiwifruit (Actinidia deliciosa). The disease occurs during flowering in the late May and disease outbreaks associated with rainfall during the flowering season have resulted in a severe reduction in kiwifruit production. The causal organism isolated from diseased blossoms of kiwifruits was identified as Pseudomonas syringae pv, syringae based on the physiological and biochemical characteristics and pathogenicity test. Dead fruit stalks, dead pruned twigs, fallen leaves and soils mainly provided R syringae pv. syringae with overwintering places in the kiwifruit orchards, and the inocula also overwintered on buds, trunks, branches, and twigs on the kiwifruit trees. Among the overwintering places, the incula were detected in the highest frequencies from dead fruit stalks. The population density of P. syringae pv. syringae was speculated to be over $1{\times}10^4$cfu/ml for the bacterial infection, and the optimum temperature for the bacterial growth ranged 20 to $25^{\circ}C$. The highest population density of P. syringae pv. syringae on the overwintering places was detected in May and June when the daily average temperature coincided with the optimum temperature for bacterial growth of P. syringae pv. syringae.

• Journal of the Korean Wood Science and Technology
• /
• v.34 no.3
• /
• pp.84-89
• /
• 2006

Cultivation of cauliflower mushroom (Sparassis crispa) became a good way of consumption for coniferous sawdust. However, conventional method for the cultivation demanded ready-decomposed sawdust in field more than 6 months, which resulted in the spatial and temporal problems. This study was conducted to develop an efficient cultivation method to minimize the problem with steam-treated sawdust media of Larix leptolepis, Pinus densiflora and Pinus koraiensis. By the treatment, mycelial growth was stimulated by 10% compared to that of untreated sawdust with the sawdust media of L. leptoiepis and P. koraiensis, and the mushroom productivity was improved from 12.5% (50.1 g/400 g) to 16.7% (66.7 g/400 g) with the sawdust medium of P. densiflora from first harvest in case of KFRI644. Steam treatment is thought to be a good method for cultivation of cauliflower mushroom by minimizing culturing period and increasing productivity, which is an effective way of utilization for coniferous sawdusts.

• Korean Journal of Plant Resources
• /
• v.33 no.1
• /
• pp.1-14
• /
• 2020

This study was conducted to analyze community structure and species composition of Pinus densiflora for. erecta Stand in Mt. Cheonchuk (653 m). Field survey was carried out from June to September in 2013. 74 plots (20×20 m) were set up, 5 herb layer plots (3×3 m) were constructed for each plot, and there, Diameter at Breast Heigh t(DBH), height, environmental factor, annual growth were measured. Vascular plants were surveyed as following; 66 family, 165 genus, 211 species, 2 sub species, 29 variety, 6 form 248 taxa. Results of cluster analysis for P. densiflora for. erecta forest, 3 communities were divided into; Quercus mongolica (P-1), Quercus variabilis (P-2) and Quercus aliena-Stephanandra incisa (P-3). There were significant environmental factors that organic layer, annual growth, CEC, total total nitrogen, organic matter and pH for each community. As a result of DCA, P-1 and P-2 were distributed large range of environmental factors but relatively limited in P-3. Distributions of herb layer were affected by sand, cation exchange capacity, silt and total nitrogen. Results of MRPP test for herb layer communities, it was significantly analyzed (A=0.003, P<0.008). Species diversity index was highly recorded in P-3 and influenced by cation exchange capacity, total nitrogen, annual growth in consequence of NMS analysis.

• Ecology and Resilient Infrastructure
• /
• v.9 no.2
• /
• pp.83-92
• /
• 2022

The 2020 summer extreme flood severely disturbed the riparian ecosystem of the Seomjin River. Some trees were killed by the flood impact, whereas others have recovered through epicormic regeneration after the disturbance. At the same time, several tree individuals newly germinated. This research aimed to explain the recovery of the riparian ecosystem by spatial proximity between each tree individual of different characteristics, such as "dead", "recovered", and "newly germinated". A spatial point pattern analysis based on K and g-functions revealed that the newly germinated trees and the existing trees were distributed in the spatially clumping patterns. However, further detailed analysis revealed that the new trees were statistically less attracted to the recovered trees than the dead trees, implying competitive interactions hidden in the facilitative interactions. Habitat amelioration by the existing trees positively affected the growth of the new trees, while "living" existing trees were competing with the new trees for resources. This research is expected to provide new knowledge in this era of rapid climate change, which likely induces stronger and more frequent natural disturbance than before. Environmental factors have been widely used for ecosystem modeling, but species interactions, represented by the relative spatial distribution of plant individuals, are also valuable factors explaining ecosystem dynamics.

• Research in Plant Disease
• /
• v.22 no.1
• /
• pp.18-24
• /
• 2016

This study was conducted to elucidate the cultural and pathogenic characteristics of Cladosporium cucumerinum PT1 and resistance of 81 commercial cucumbers (Cucumis sativus). Cucumber leaves and fruits appeared as scab were collected from a plastic film house located in Pyeongtaek, Gyeonggi-province, Korea in late March, 2015. A casual fungus was isolated from the diseased fruits on potato dextrose agar and it was identified as C. cucumerinum PT1 based on the morphological characteristics. To find out the effect of wounding and fruit size on the development of cucumber scab, small (<10 cm long), medium (10 to 20 cm long), and large (>20 cm long, commercially mature fruit) size cucumber fruits were harvested, C. cucumerinum PT1 pathogens were inoculated with a single droplet of suspension ($1{\times}10^5$ spores/ml) on wounded or unwounded cucumber fruits. Small fruits were completely damaged with showing severe water-soaking symptoms and fast pathogen growth regardless of wounded or unwounded. Meanwhile slight water-soaking symptoms on medium and large size fruits occurred and disease development into plant tissues was observed only on wounded fruits. Disease resistance of 81 commercial cucumber cultivars was evaluated on third-stage seedlings and small fruits by inoculating suspension ($1{\times}10^5$ spores/ml) of C. cucumerinum PT1. As a result, mini and pickling cultivar groups were resistant, 'Cheoeumcheoreom' cultivar was symptomless and the other cultivars were resistant to medium resistant. On the other hand, most of cucumber cultivars belonging to the other groups were susceptible. Disease resistance of cucumber against cucumber scab was significantly different among cultivars and a few cucumber cultivars showed different disease resistant responses to two bioassay methods using seedlings and small fruits. Therefore, to screen scab resistance in cucumber, a test using both fruits and seedlings is advisable. We think that the selected resistant cultivars can be used to control cucumber scab effectively under the farmhouse condition.

• Research in Plant Disease
• /
• v.18 no.1
• /
• pp.1-9
• /
• 2012

A total of 20 agricultural organic materials including inorganic compounds, plant oils and plant extracts were used in the study for assessing the control efficacy on pepper diseases. Among inorganic compounds, only copper hydroxide showed inhibitory effect on both Phytophthora capsici causing Phytophthora blight and Colletotrichum acutatum causing anthracnose. Phosphorous acid inhibited the growth of P. capsici on PDA, and Sulfur/quicklime had it on that of C. acutatum. Plant essential oil, rosemary oil, and rapeseed oil among plant oils and plant extract of Japanese apricot/ginkgo nut inhibited the mycelial growth of the two pathogens. In the screening using pepper plant seedlings, the control efficacy on Phytophthora blight in 6-leaf stage of seedling was superior to that in 4-leaf stage of seedling. A protective effect on Phytophthora blight was displayed by copper hydroxide, sulfur/quicklime, water soluble calcium, phosphorous acid, plant essential oil, and cloves extract. When C. acutatum was inoculated by the non-wound method, copper hydroxide and rapeseed oil showed excellent protective activities with control values of 91.3% and 82.6%, respectively. However, copper hydroxide did not show any activity, when C. acutatum was inoculated after wounding pepper fruits. All organic materials never showed the curative effect on Phytophthora blight and anthracnose in pepper seedling assay and fruit assay.

• Korean journal of applied entomology
• /
• v.24 no.2 s.63
• /
• pp.65-70
• /
• 1985

The locational preference of the brown planthopper (BPH) Nilaparvata lugens ($St{\aa}l$) and the whitebacked plant hopper (WBPH) Sogatella furcifera(Horvath) was studied on rice cultivars IR22 and IR36 as an integral part of subsequent research on insect-fungal pathogen relationships. The BPH was observed to stay consistently on the basal portion while the WBPH showed a general preference for the upper portion regardless of varieties, rice growth stages and insect population density levels. The habitat preference of both species (BPH and WBPH) was found not to be affected by the presence of the other species when both species are present on the same host plant Five rice cultivars with different reactions to BPH biotype 2 were used in the study on BPH-Rhizoctonia solani relationship: IR22 and TN1 (susceptible); Triveni and ASD7 (moderately resistant); and IR42 (resistant). Test plants were inoculated with R. solani (Kuhn) $3{\sim}4$days after insect infestation. Sheath blight disease severity/incidence was significantly higher in the treatment where BPH+R. solani were together than in the treatment with only the pathogen. Symptom expression of the disease in the BPH-pathogen combination was faster and mycelial growth was more profuse inducing the formation of more infection structures. Regardless of varietal reaction to BPH biotype 2, the degree of hopperburn was significantly higher in the combination of the two pests as compared with that of BPH alone. There could be a synergistic relationship between the insect pest and the pathogen indicated by a positive interaction between the two species.

• The Korean Journal of Ecology
• /
• v.17 no.3
• /
• pp.299-310
• /
• 1994

Intraspecific clonal interactions have important influences on a population structure of the cellular slime mold (CSM). This study was to investigate whether or not evolutionary change in a population could be induced by clonal competition, and to elucidate how various clones in a population evolve in a homogeneous environment of laboratory culture. The characteristic clones of Polysphondylium pallidum which had different resource consumption rates (RCR) and mating types I and II were selected for study. Investigation was conducted for 4 experimental time interval $(T_0-T_4)$; one experimental time interval took almost 10-14 days from inoculation to havest of fruiting bodies. Two sets of 50 clones were cultured from 50 clones at To, and RCR variations of the population were compared between $(T_0\;and\;T_4)$ for each set of clones. Each clone of the CSM had a diverse resource consumption rate, or growth rate, in a homogeneous and limited Cerophyl agar plate despite the passage of 48-56 generations from the beginning of the experiment. Diverse clones with different growth rate could coexist in one site of the homogeneous agar plate as well as heterogeneous soil microenvironment. When there was high clonal diversity of RCR, a clone in a population had high chances to encounter other clones with resultant increased clonal competition. In one set, 26 of 37 clones of mating type I were changed to mating type Il for the 4 experimental time intervals, which indicated that the rate of competitive exclusion among clones during total experiment from $(T_0\;to\;T_4)$ was 0.703. In another set, 31 of 37 clones of mating type I were changed to mating type II , having the rate of competitive exclusion 0.838. The frequency of each of mat~ng types changed by 0.93-1.29% in each successive generation. The competitive exclusion among clones occurred by 1.26-1.75% when approximately $2.6{\times}10^8$ bacterial cells were provided as food and thereafter one generation of myxamoebae of CSM elapsed at room temperature. This finding implicated that in the vegetative state of P, pallidurn there was 1.26-1.75% probabil~ty of evolutionary change per generation changing from one clone to another clone.

• The Korean Journal of Pesticide Science
• /
• v.21 no.1
• /
• pp.26-32
• /
• 2017

Antimicrobial activity of 6 phosphate compounds as $H_3PO_3$, $H_3PO_4$, $K_3PO_4$, $K_2HPO_4$, $KH_2PO_4$ and $NH_4H_2PO_4$ against Phytophthora capsici JHAW 1-2 and Colletotrichum acutatum JC24 was investigated in this study. Inhibitory effect on zoospore release, zoosporangia germination and zoospore germination was superior than mycelial growth. Among 6 compounds, $H_3PO_3$ and $H_3PO_4$ showed the best antimicrobial activity against P. capsici JHAW 1-2. Diseases controlling activity of the phosphate compounds tested on seedling and fruit of pepper against Phytophthora blight was also better than those against anthracnose. When $H_3PO_3$ was applied to the pepper seedlings at a concentration of $100{\mu}g\;mL^{-1}$, severe phytotoxicity was occurred. However, with applying $10{\mu}g\;mL^{-1}$ of $H_3PO_3$ showed 100% the disease control efficacy. In case of $100{\mu}g\;mL^{-1}$ $H_3PO_4$ application showed excellent antimicrobial activity against P. capsici JHAW 1-2, and 56.7% of the disease control efficacy with no phytotoxicity. To investigate the control efficacy against anthracnose, conidia suspension was inoculated with non-wound and wound inoculation method on pepper fruit. Among 6 compounds, only $100{\mu}g\;mL^{-1}$ of $H_3PO_3$ and $H_3PO_4$ had a activity of more than 70%, but the control activity on other treatments was minimal or unacceptable.