• Weed & Turfgrass Science
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• v.7 no.3
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• pp.275-282
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• 2018

Miscanthus species are known as a genus of eco-friendly and low-maintenance cost ornamental grasses. Plug and cutting methods were tested for multi-propagation of most promising ornamental Miscanthus species in greenhouse and field plot. The plug formation period with three different cell sizes with four cultivars (M. sinensis 'Andersson', 'Strictus', 'Gracillimus', 'Variegatus') were evaluated the seedling development stages with two irrigation types of the over-head and the bottom watering in greenhouse and field plot afterward during 2015-2016 season. In seedling plug test, the size of tray cell affected the plug formation. Bottom irrigation resulted positively on plant height, weight, root and tiller development compared with the over-head irrigation. Plug cell size affected the plant growth in the field after transplanting. All of the 3 Miscanthus species showed higher rates of successful propagation at the lower nodes before inflorescence formation (vegetative growth stage). To analyze the survival factors of M. xgiganteus cutting, the cutting time, node part, and culm diameter were tested as independent variables with the binary logistic model. The survival probability was influenced by node part and culm diameter significantly. The third and fifth node parts showed 0.12 (8X higher failure probability) and 0.02 (50X higher failure probability) times less survival probability. It means the survival probability will be increased by using older and lower part of cuttings during a vegetative growth stage before inflorescences of M. xgiganteus.

• Korean Journal of Weed Science
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• v.14 no.4
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• pp.258-264
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• 1994

The weed survey in lowland rice field in 1992 was conducted to identify weed population change as affected by different elevation, soil type and cultivation pattern at Gangweon province. There were more perennial weeds in plain and east coastal area while more annual weeds in mid alpine and alpine area. Meanwhile, perennial weed species was more dominant at ordinary and sandy soil but annual weed species was more dominant at poorly drained soil. In general, hand and machine(30 day old seedling) transplanting would result in higher dominant weed species of perennial while there was more annual weed species in machine (10 day old seedling) transplanting and dry seeding, respectively. Also, annual weed species was more predominant at spring plowing time compared to autumn plowing time. Particularly, there was change in dominant weed species with time. In 1971 annual weed species was more predominant but perennial weed species was highly dominant in 1981 and 1992.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.3
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• pp.193-202
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• 2017

This study was carried out in 2014 and 2015 to investigate the effect of transplanting density on panicle production and to analyze the relationship of panicle production with yield traits in the mid-maturing quality rice cultivar 'Haiami' in the mid-plain area of Korea. Number of tillers per square meter increased by reducing planting distance and increasing seedling number per hill. These effects were maintained until maturity and were reflected in the final number of panicles per square meter, although the effect of planting density decreased as rice growth progressed. However, increased panicle number per square meter following dense planting did not improve head rice yield. Panicle number per square meter was negatively associated with spikelet number per panicle and was not correlated with other yield components or head rice yield. Head rice yield was not correlated with head rice percentage but was closely and positively correlated with milled rice yield. Milled rice yield did not increase with grain filling percentage but increased with spikelet number per square meter. Spikelet number per square meter increased with both spikelet number per panicle and panicle number per square meter, although the former had a greater influence. Therefore, we conclude that head rice yield of the 'Haiami' cultivar grown in the mid-plain area of Korea is not improved with an increased panicle number following high planting density but it could be improved with high milled rice yield by increasing spikelet number per unit area.

• Research in Plant Disease
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• v.14 no.1
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• pp.51-56
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• 2008

Powdery mildew of lettuce that is a newly reported disease became a threat to organic cultivation of lettuce in Korea since the disease caused by Podosphaera fusca resulted in a half of yield loss in heavily infected fields. To improve micro-environmental conditions around lettuce, ACF (air-circulation fan) was installed on inside roof of plastic house at 6 m intervals. The ACF increased 57% of lettuce yield and reduced 71.4% of lettuce seedling death. COY (cooking oil and yolk mixture) consisted of cooking oil 0.3% and egg yolk 0.08% reduced lettuce seedling death from 89.3% to 92.9% under the greenhouse. Seven-day interval spray of COY resulted in high control values of powdery mildew of lettuce ranging from 89.6% to 96.3%, which was comparable to a fungicide, Azoxystrobin. Lettuce yield was increased about two times compared to a non-treated conventional cultivation. Qualities of lettuce such as hardness and chlorophyll content were also improved by COY and ACF combination. Effect of COY on control of the disease was improved when $CaCO_3$ or $SiO_2$ 1,000 ppm was supplemented. Results indicated that the COY made of cooking oil such as canola emulsified with yolk was highly effective on control of powdery mildew of lettuce and suitable for organic agriculture, especially when combined with ACF.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.60-73
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• 1989

Two field experiments were carried out to assess the applicability of a central composite design (CCD) in determining optimum culture condition of an early rice cultivar, Unbongbyeo in southern Korea. A central composite design with two replicates was applied to five levels of five factors such as the number of hills per 3.3m2, the number of seedlings per hill, the levels of nitrogen, the transplanting date and the seedling age (Experiment 1). The levels of planting density were ranged from 30 hills to 150 hills per 3.3m2 ; the number of seedlings per hill from 1 seedling to 9 seedlings per hill; the levels of nitrogen application from 1 kg/l0a to 21 kg/l0a; the transplanting date from June 15 to July 5; the seedling age from 25 days to 45 days. A fractional factorial design was applied to three levels of five factors tested in CCD (Experiment 2). Yield per hill and per unit area were examined and the results obtained from both experiments were compared. The benefits from the central composite design were discussed. Maximum yield of brown rice per unit area was obtained at the combination of the central levels of one of five factors when the other four factors were fixed at central point. Furthermore, brown rice yield per unit area affected by interaction of two factors was maximized at the central point when the remain three factors being fixed at the central level. The responses of five factors to brown rice yield per hill and unit area were found to be a saddle point in both designs. Actual values of the stationary points were 107 hills per 3.3 m2, 4 seedlings per hill, 10 kg nitrogen per l0a, transplanting date of rice on June 26 and 33 days of seedling age in the central composite design. Brown rice yield per unit area at the stationary points were estimated 439 kg/l0a in the central composite design and 442 kg/l0a in the fractional factorial design. Considering the number of experimental treatment combinations, the central composite design was rather convenient in reducing the number of treatment combinations for similar information. It was more convenient for an experimenter to present the results from the central composite design than those from the fractional factorial design. Considering the optimum yields of brown rice per unit area at the stationary points being verified as saddle points in both designs. inter-heterogeneity of each of the factors should be avoided in setting up factors in pursuit of inducing unidirectional response of the factors to yield. Even though both the lower and higher levels in the central composite design being beyond the region of an experimenter's interest. they were considered highly valued in interpretation of the results. Conclusively. the central composite design was found to be more beneficial to optimize culture condition of paddy rice even with several levels of various factors were involved.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.49-49
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• 2015

Over the past decade, clubroot has emerged as a major constraint to canola (Brassica napus) production in central Alberta, Canada. The number of fields with confirmed P. brassicae infestations in Alberta has increased steadily from 12 in 2003 to nearly 2,000 in 2014. Management of clubroot on canola has focused on sanitization of field equipment, soil amendments to reduce viable pathogen populations, long rotations out of susceptible crops and cropping of resistant cultivars. Clubroot resistance is the most effective and economical method of disease mitigation, but the recent identification of isolated P. brassicae populations with novel virulence phenotypes capable of overcoming resistance in most canola cultivars highlights the variable nature and adaptability of the pathogen. Recent studies have shown slight reductions in pathogen populations through crop rotations, but much more substantial reductions in spore populations in heavily infested areas near field entrances using fumigants such as Vapam (metam-sodium) or Basamid (dazomet). Greenhouse trials showed that seedling emergence, plant height and root weight increased, while primary and secondary infection and disease severity decreased with increased Basamid dosage. However, field trials showed some phytotoxicity. Application of Vapam at rates of 0.4 to $1.6mL\;L^{-1}$ soil resulted in 12-16 fold reductions in clubroot severity and primary and secondary infection. Vapam also was effective in reducing clubroot severity and improving canola seed yield under field conditions. These studies underscore the need for good resistance stewardship and for the integration of multiple products and practices for successful management of clubroot on canola.

• BMB Reports
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• v.49 no.12
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• pp.693-698
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• 2016

In this study, a tissue-specific GAL4/UAS activation tagging system was used for the characterization of genes which could induce lethality when ubiquitously expressed. A dominant mutant exhibiting stunted growth was isolated and named defective root development 1-D (drd1-D). The T-DNA tag was located within the promoter region of AtTX12, which is predicted to encode a truncated nucleotide-binding leucine-rich repeat (NLR) protein, containing a Toll/interleukin-1 receptor (TIR) domain. The transcript levels of AtTX12 and defense-related genes were elevated in drd1-D, and the misexpression of AtTX12 recapitulated the drd1-D phenotypes. In the presence of ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1), a key transducer of signals triggered by TIR-type NLRs, a low-level of AtTX12 misexpression induced strong defective phenotypes including seedling lethality whereas, in the absence of EDS1, a high-level of AtTX12 misexpression induced weak growth defects like dwarfism, suggesting that AtTX12 might function mainly in an EDS1-dependent and partially in an EDS1-independent manner.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.104.2-105
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• 2003

Bacterial isolates, CC178, PTC25, HC39 and KY165 originally obtained from the leaves of cucumber or tomato were selected for biocontrol agents against gray mold of cucumber and tomato by in vivo cucumber seedling assay. Each suspension of the selected epiphytic bacteria were sprayed three times at seven-day interval from early stage of cucumber in a field. Incidence of gray mold on cucumber fruits treated with isolates CC178, PTC25, HC39 and KY165 was 15.3％, 18.2％, 23.6％, and 10.4％, respectively, whereas that of control was 38.0％ after 7 days of final spray. On the other hand, treatment with the selected isolates, CC178, PTC25, HC39, and KY165 on tomato showed 2.2％, 1.3％, 2.9％, and 3.5％ in the incidence of gray mold on leaves, whereas that of control was 9.3％. All selected isolates had strong antagonistic activity against Botrytis cinerea on dual culture plate assay.

• The Korean Journal of Ecology
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• v.20 no.6
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• pp.413-421
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• 1997

Ecological characteristics of Rumex acetosella have been studied both in the laboratory and in the field. R. acetosella grows well straight up after germination, elongating and thickening their rhizomes with sprouts erupting along their bodies of the rhizome. The number and development of leaves and ramets reach their peak by April. The size of leaves and the cover degree of the plant increase from April to May. R. acetosella is an ephemeral, a short life mode plant, finishing its life cycle in July or August. The germination and seedling growth of selected species exposed to aqueous extracts of R. acetosella were in inverse proportion to concentration. The growth of Rumex japonicus and Digitaria sanguinalis cultivated in soil with R. acetosella was more inhibited than that of the control. Twelve chemical compounds were identified from R. acetosella by GC and HPLC and verified by bioassay with the same chemical reagents. It would be assdumed that these chemical substances are responsible for the allelopathic effect of R. acetosella. In short, R. acetosella plants grow vigorously from April and maintain their superior competitive ability to other plants in forming their communities by emitting chemical substances into their environment.

• Journal of Environmental Science International
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• v.25 no.8
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• pp.1051-1056
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• 2016

The growth characteristics of Paeonia ostii 'Fengdan' seedlings roots in response to trichokonins-spray treatment were investigated in this study. One-year-old seedlings of P. ostii 'Fengdan' were potted in plastic cups containing garden mold and grown under field conditions. The results showed that application of trichokonins significantly promoted root growth in P. ostii 'Fengdan' seedlings. The total root projection area, total root surface area, total root volume, total root length, root number and root diameter of seedlings treated with 0.25 mg/L trichokonins were higher by 141.70, 116.59, 119.44, 55.97, 348.88 and 127.78%, respectively, than that of the control. Thus, the results supported the hypothesis that good growth condition for roots could directly improve their nutrient absorption and utilization efficiency, promoting plant growth and development.