• Journal of Bio-Environment Control
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• v.7 no.3
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• pp.253-258
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• 1998

Lettuce plants(Lactuca sativa var. capitata L.) were subjected to nitrogen starvation for 18, 14, 11, 7, and 0 days before harvest. The nitrate content of lettuce was decreased greatly by nitrogen starvation and also its fresh weight. The nitrate content of the middle part of leaves was lowest at the treatment of 18 days before harvest. In the inner part it was lowest at the treatment of 11 and 14 days before harvest. The longer the period of nitrogen starvation was, the more were decreased the absorption rates of cations at harvest. During the experiment, the pH was decreased except the treatment of 7 days before harvest. The EC was continuously increased regardless of treatments.

• Korean Journal of Organic Agriculture
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• v.9 no.1
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• pp.17-27
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• 2001

To clarify the proper and safe duration of maturation periods for sawdust-pig manure composts, leaf lettuces were applied with pig manure composts fermented for 15, 30, 45, 60, 75 days and 1 year (control) and cultivated in a plastic house with or without additional PE film tunnel. The changes in physiochemical properties of soil and leaf lettuce growth were measured. Shorter duration of maturation periods enhanced the generation of N $H_3$ gas from the composts and resulted in significant decrease in seed germination, growth and yield of leaf lettuce. Under with and without PE tunnel conditions the concentration of N $H_3$ from compost over 3.8 and 2.1 mg/100g composts, respectively induced growth reduction. In proportion to the increase of maturation duration saw-dust containing pig manure exhibited decrease in C/N ratio, N $H_4^{+}$-N, N $H_4^{+}$N $O_3^{-}$ ratio but increase in N $O_3^{-}$-N contents. In case of applying pig manure compost without PE film tunnel condition the minimum maturation period of pig manure composts for safe leaf growth was 60 days, while minimum 75 days of maturation was required when applied with PE film tunnel. tunnel.

• The Korean Journal of Ecology
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• v.23 no.2
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• pp.149-155
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• 2000

The allelopathic effects of Artemisia lavandulaefolia were studied using several test plants and microbes. Aqueous extracts and volatile compounds of A. lavandulaefolia inhibited seed germination, seedling and root growth of the test species such as Achyranthes japonica. Lactuca sativa, Artemisia princeps var. orientalis. Oenothera odorata, Plantago asiatica. Aster yomena, Elsholtzia ciliata, and Raphanus sativus var. hortensis for. acanthiformis. The root growth of test species was more affected than shoot growth by allelochemicals of A. lavandulaefolia. Essential oil of A. lavandulaefolia had antibacterial and antifungal effects. However, the antimicrobial activity of the essential oil was dependent upon the microbial species and concentrations. Callus growth of Oryza sativa, Brassica campestris subsp. napus var. pekinensis and Achyranthes japonica was sensitive by the essential oil of A. lavandulaefolia. Twenty three chemicals were identified from A. lavandulaefolia essential oil by gas chromatography. Primary allelochemicals among them were 1, 8-cineole, 1-$\alpha$-terpineol, $\alpha$-terpinene. camphor, 2-buten-1-ol and azulene. We concluded that aqueous extract and essential oil of A. lavandulaefolia were responsible for allelopathic effects.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.114-114
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• 2017

The aim of this research is to improve Korean lettuce varieties in terms of Fusarium wilt, bolting under hot weather and nutritional function applying genomics approaches. To find related gene/molecular markers, we selected 96 lettuce varieties which are popular in domestic fresh vegetable markets. To construct frame works of the genomic approaches, we exploited GBS(Genotyping by Sequencing) and found total 61,407 SNPs from lettuce whole genomes (MAF>0.02). We observed that Three SNPs array per 100kb of lettuce genome. Average LD decay is expected to expand up to 3.9M(million)bp. Thus, we concluded that about 104 SNPs exist within a LD, which is sufficient to use GWAS(Genome-wide Association Study) to explore the useful gene/molecular markers. In addition, we optimized mass screening method to evaluate disease resistance levels against Fusarium wilt and are testing the bolting sensitivity during summer growing season for those lettuce allele mining set.

• Korean Journal of Organic Agriculture
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• v.19 no.4
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• pp.589-602
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• 2011

In this study, experiments were conducted to determine the effect of different compost teas on plant growth reponses and yield of leaf lettuce. Compost tea is a liquid extract of compost obtained by mixing compost and water for a defined period of time. The pig manure and spent mushroom compost were made by steeping compost in water. Compost tea was aerated from 24 hours and molasses and kelp were added as supplements. The four types of compost were tested growth of lettuce. EC of animal manure compost tea was higher than that of spent mushroom compost tea. Mineral nutrients were significantly higher in animal manure compost tea compared with spent mushroom compost tea. Compost tea contains nutrient and a ranges of different organisms. The beneficial fungi and actinomycetes were prominent in a spent mushroom compost tea. Compost tea from animal manure had the higher numbers of total bacteria. The actinomycetes densities were high in spent mushroom compost tea. But actinomycetes were not founded in animal manure compost tea. The growth characteristics of lettuce in animal manure compost tea were higher than those of spent mushroom compost tea. And also SPAD value in leaf was high in plot treated with animal manure compost tea. The fresh yield of lettuce in animal compost tea was higher by 181% that of control plot. The effect of compost tea on growth of lettuce was largely attributable to mineral nutrient.

• The Korean Journal of Ecology
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• v.23 no.6
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• pp.431-434
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• 2000

To examine the allelopathic potentials of Chrysanthemum boreale, aqueous extracts and essential oil of the plant were used in these experiments. Seed germination of the receptor species was inhibited by the aqueous extracts and the inhibitory effect was increased in proportion to the concentration of extracts. In contrast, seedling elongation showed varied results. Achyranthes japonica, Bidens bipinnata, Raphanus sativus var. hortensis for. acanthiformis, Plantago asiatica, Pimpinella brachycarpa and Lactuca sativa were inhibited by increasing concentration of the aqueous extract, while Brassica campestris subsp. napus var. pekinensis and Echinochloa crus-galli were stimulated by the extract. Dry weight was also inhibited proportionally by increasing concentration of the aqueous extract, while some species were stimulated by a lower concentration of the extract. The volatile substances of C. boreale did not affect the seed germination of receptor plants, but seedling elongation and dry weight of some species were inhibited dose-dependently. Root hair development of selected plants was inhibited along with the concentration of essential oil. The above mentioned results, therefore, confirmed that the natural substances from C. boreale had allelopathic potentials to other plants.

• Journal of Environmental Science International
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• v.26 no.1
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• pp.109-118
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• 2017

This study was conducted to investigate the effects of intermittent plasma and electrolysis treatments on lettuce (Lactuca sativa var. oak-leaf.), nutrient solution components ($NO_3{^-}-N$, $NH_4{^+}-N$, $PO{_4}^{3-}-P$, $K^+$, $Ca^{2+}$ and $Mg^{2+}$) and environmental parameters (electrical conductivity, total dissolved solids and pH). The recirculating hydroponic cultivation system consisted of planting port, LED lamp, water reservoir and circulating pump. Nutrient solution was circulated in the following order: reservoir ${\rightarrow}$ filtration-plasma or filtration-electrolysis ${\rightarrow}$ planting port ${\rightarrow}$ reservoir. The results showed that nutrient solution components and environmental parameters were changed by plasma or electrolysis treatment. Lettuce growth was not affected by the intermittent plasma or electrolysis treatment with 30 minutes or 90 minutes, respectively. The roots of the lettuce was damaged by excessive plasma and electrolysis treatment. Electrolysis treatment had greater effect on than plasma treatment because of the accumulation of high levels of TRO (Total Residual Oxidants).

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.4
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• pp.25-42
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• 2018

The purpose of this study is to present the basic data for management of ecologically restored stream by surveying and analysing the vascular plants distributed in Chunghyocheon stream, Gyeongju-si. The survey of vascular plants in this site was conducted before and after restoration. The number of vascular plants were summarized as 276 taxa including 68 families, 188 genera, 242 species, 1 subspecies, 29 varieties and 4 forms. The rare plants were 2 taxa including Prunus yedoensis Matsum. and Iris ensata var. spontanea (Makino) Nakai, and the Korean endemic plant was Lespedeza maritima Nakai. The specific plants by floristic region were 13 taxa including 1 taxa of grade V, 3 taxa of grade III, 1 taxa of grade II and 8 taxa of grade I. The naturalized plants were 62 taxa including Persicaria orientalis (L.) Spach, Lepidium virginicum L., Poa compressa L. and so forth. The invasive alien plants were 3 taxa including Ambrosia artemisiifolia L., Aster pilosus Willd. and Lactuca scariola L.. The hydrophytes were 34 taxa including 26 taxa of emergent plant, 1 taxa of floating-leaved plant, 2 taxa of free-floating plant and 5 taxa of submerged plant.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.5
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• pp.15-41
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• 2017

The purpose of this study is to present the basic data for conservation of forest ecosystem by surveying and analysing the flora distributed in Nakdong-Jeongmaek Mountains, Korea. The numbers of flora were 901 taxa including 116 families, 433 genera, 790 species, 4 subspecies, 90 varieties, 15 forms and 2 hybrids. The threatened species was Pedicularis ishidoyana. The rare plants were 33 taxa including Pseudostellaria sylvatica, Cimicifuga heracleifolia var. bifida, Isopyrum mandshuricum, Paeonia japonica, Syringa patula var. kamibayshii, Lilium distichum, Iris odaesanensis and so forth. The Korean endemic plants were 35 taxa including Salix koriyanagi, Thalictrum actaefolium var. brevistylum, Corydalis maculata, Lespedeza maritima, Cirsium setidens, Carex okamotoi and so forth. The specific plants by floristic region were 155 taxa including 55 taxa of grade I, 41 taxa of grade II, 36 taxa of grade III, 18 taxa of grade IV and 5 taxa of grade V. The naturalized plants were 62 taxa including Rumex obtusifolius, Amaranthus lividus, Medicago sativa, Geranium carolinianum, Malva sylvestris var. mauritiana, Foeniculum vulgare, Sonchus oleraceus, Tradescantia reflexa and so forth. The invasive alien plants were 5 taxa including Rumex acetocella, Solanum carolinense, Ambrosia artemisiifolia, Aster pilosus and Lactuca scariola.

• Journal of Environmental Science International
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• v.24 no.8
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• pp.1075-1084
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• 2015

This study was conducted to investigated the changes in the nutrient components ($NO_3{^-}-N$, $NH_4{^+}-N$, $PO_4{^{3-}}P$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$) and environmental parameters (electrical conductivity, total dissolved solids and pH) on the leaf lettuce (Lactuca sativa L.) grown with hydroponics. Recirculating hydroponic cultivation system was consisted of planting port, LED lamp, water tank, and circulating pump for hydroponic. Nutrient solution was used in the standard solution for Japan vegetables experimental station and commercial hydroponic. The result showed that electrical conductivity (EC), total dissolved solids (TDS) and pH, depending on the growth of lettuce decreased continuously. With the growth of the lettuce, nitrate nitrogen, ammonia nitrogen, phosphate phosphorus were required for periodic replacement. The number of pH compensation due to the growth of lettuce are the most high. The concentration of $Ca^{2+}$ and $Mg^{2+}$ during the lettuce growth showed no significant change. However, $K^+$ concentration increased due to the replacement with nitrogen and phosphorus. Electric conductivity and total dissolved solids with total nutrient concentration showed the linear relationship and the correlation coefficient $R^2$ were 0.8601 and the 0.827, respectively.