• Korean Journal of Weed Science
• /
• v.17 no.4
• /
• pp.382-389
• /
• 1997

Collated data from the 1995-1996 floristic surveys of weeds of arable peat in Selangor district were analysed to assess composition and dominance and spatial distribution pattern based on quantitative and dispersion indices. Forty eight weed species belonging to 19 families of which 31 were broad leaves, 10 grasses and 7 sedges were sampled and these ware translated as 77.8 and 15% of the total cover, respectively, The respective important values were 71.11 and 18%. Ten species in the onder of dominance were Fimbristylis acuminata, Murdannia nudiflora, Hedyotis corymbosa, Ageratum conyzoides, Asystasia gangetica, Cleome rutidosperma, Cyperus sphacelatus, Lindernia crustacea, Ludwigia hyssopifolia of spatial distribution based on variance-to-mean ratios, Llouds mean crowding or Lloyds patchiness indices. Other species were either random or regular in their spatial distribution. Differences in species-dominance and spatial distribution pattern may be attributed to inherent variations in patchiness and fecundity schedules of each weed species, crops, cropping patterns and agronomic practices prevailing in the area.

• Korean Journal of Agricultural Science
• /
• v.41 no.3
• /
• pp.163-167
• /
• 2014

The average temperatures for year and winter season have been risen by $0.7{\circ}C$ and $1.4{\circ}C$, respectively, during the last 30 years. Recently abnormal climate phenomena occurred frequently results in severe loss of vegetable crops grown in Korea. Specially, Chinese cabbages grown in the southern area of Korea are often significantly affected by sudden cold waves during winter season before harvest. This experiment was conducted to find out a potential role of covering materials on the protection of frost damage of 'Bularm' chinese cabbage in the winter season. The lowest temperature was $-15.8^{\circ}C$ in non-covering, $-8.1^{\circ}C$ in the PE film covering and $-4.6^{\circ}C$ in the non-woven fabric covering with PE film, respectively. The cumulative times below $4.0^{\circ}C$ were 145.5 hours for the non-covering treatment, 94 hours in the PE film covering and 14.5 hours in the non-woven fabric covering with PE film, respectively. The symptoms of frost damage were severe at non-covering chinese cabbages compared to polyethylene film (PE) non-woven fabric with PE covering ones. Microscopic studies showed the normal anatomical structure of palisade and spongy tissue of cabbage leaves covered with non-woven fabric with PE film. Leaf cells, however, were slightly damaged in cabbages covered with PE film alone, and both palisade and spongy cells were were completely collapsed in uncovered cabbages. The result of this study suggests that chinese cabbages is required to be covered with non-woven fabric with PE film to minimize the frost damage by sudden cold wave below $-7^{\circ}C$.

• Korean Journal of Soil Science and Fertilizer
• /
• v.33 no.1
• /
• pp.8-14
• /
• 2000

Long term cultivation crops like tomato, capsicum, melon etc. demand much amount of continuous supplying of nutrition during the whole growing periods. It is not easy to cover satisfactorily the nutritional demands for them by splitted top dressings, slow release fertilizer applications and fertigation systems. To overcome these problems, the "CULTAN" (Controlled Uptake Long Term Ammonium Nutrition) Beaker Deposit techniques have been developed and it was put into PVC beaker with the combined nitrogen fertilizer type mixed with the ratio of one-third of ammonium sulfate-N and two-thirds of urea-N, in which nitrogen was loaded on the demanding amount of a tomato plant during the growing period. Gypsum was mixed as a binder, and loamy soil and compost were used as a diffusion regulator. It was placed upside down into root zone of tomato at the transplanting. Tomato roots were spreaded into the Deposit beaker by ammonium ions which attract root growth. The tomato fruit yield and nitrogen uptake by plant were increased by application of $NH_4$-Beaker deposit fertilizer rather than those of common fertilizer treatment. In conclusion, it was able to improve economic and ecological benefits through CULTAN system compared with common fertilization systems. CULTAN system was estimated as a prospective alternative to enhance productivity and minimize nutrient lose. In addition, it shows further developing possibility of CULTAN system by the supplement of micro-nutrients and pesticides in the macro-nutrient beaker deposits.

• Journal of Plant Biotechnology
• /
• v.48 no.3
• /
• pp.124-130
• /
• 2021

Nitrate is an important nutrient and signaling molecule in plants that modulates the expression of many genes and regulates plant growth. In this study, we cover the research status of transcription factors related to the control of gene expression by nitrate signaling in higher plants. Nitrate reductase is a key enzyme in nitrogen assimilation, as it catalyzes the nitrate-to-nitrite reduction process in plants. A variety of factors, including nitrate, light, metabolites, phytohormones, low temperature, and drought, modulate the expression levels of nitrate reductase genes and nitrate reductase activity, which is consistent with the physiological role if. Recently, several transcription factors controlling the expression of nitrate reductase genes have been identified in higher plants. NODULE-INCEPTION-Like Proteins (NLPs) are transcription factors responsible for the nitrate-inducible expression of nitrate reductase genes. Since NLPs also control the nitrate-inducible expression of genes encoding the nitrate transporter, nitrite transporter, and nitrite reductase, the expression levels of nitrate reduction pathway-associated genes are coordinately modulated by NLPs in response to nitrate. Understanding the function of nitrate in plants will be useful to create crops with low nitrogen use.

• Korean Journal of Soil Science and Fertilizer
• /
• v.37 no.4
• /
• pp.199-206
• /
• 2004

Factors of universal soil loss equation, USLE, and its revised version, RUSLE for Korean soils were reevaluated to estimate the national scale of soil loss based on digital soil maps. Rainfall erosivity factor, R, of 158 locations of cities and counties were spacially interpolated by the inverse distance weight method. Soil erodibility factor, K, of 1321 soil phases of 390 soil series were calculated using the data of soil survey and agri-environmental quality monitoring. Topographic factor, LS, was estimated using soil map of 1:25,000 scale with soil phase and land use type. Cover management factor, C, of major crops and support practice factor, P, were summarized by analyzing the data of lysimeter and field experiments for 27 years (1975-2001) in the National Institute of Agricultural Science and Technology. R factor varied between 2322 and 6408 MJ mm $ha^{-1}$ $yr^{-1}$ $hr^{-1}$ and the average value was 4276 MJ mm $ha^{-1}$ $yr^{-1}$ $hr^{-1}$. The average K value was evaluated as 0.027 MT hr $MJ^{-1}$ $mm^{-1}$. The highest K factor was found in paddy rice fields, 0.034 MT hr $MJ^{-1}$ $mm^{-1}$, and K factors in upland fields, grassland, and forest were 0.026, 0.019, and 0.020 MT hr $MJ^{-1}$ $mm^{-1}$, respectively. C factors of upland crops ranged from 0.06 to 0.45 and that of grassland was 0.003. P factor varied between 0.01 and 0.85.

• Journal of Environmental Impact Assessment
• /
• v.26 no.2
• /
• pp.127-139
• /
• 2017

Measurements of net ecosystem exchange (NEE) of $CO_2$ based on the eddy covariance technique provide reasonable carbon balance estimates in response to local environmental conditions. In South Korea, the forest ecosystems cover approximately 64% of the total area, thereby strongly affecting regional carbon balances. Cultivated croplands that cover about 17% of the total area should also be considered when calculating the carbon balance of the country. In this study, our objectives were (a) to quantify the range and seasonal variation of NEE at forest ecosystems, including deciduous, coniferous, and mixed forests, and agricultural ecosystems, including rice paddies and a potato field, in South Korea and (b) to compare NEE at ten Fluxnet sites that have the same or similar ecosystems as found in South Korea. The results showed that the forest and agricultural ecosystems were carbon sinks. In Korea, NEE at the forest ecosystems varied between -31 and $-362gC/m^2/yr$, and NEE at the croplands ranged from -210 to $-248gC/m^2/growing$ season. At the deciduous forest, NEE reached low values in late spring, early summer, and early autumn, while at the coniferous forest, it reached low values in spring, early summer, and mid autumn. The young mixed forest was a much stronger carbon sink than the old-growth deciduous and coniferous forests. During each crop growing season, beet had the lowest NEE value within six crops, followed by wither wheat, maize, rice, potato, and soybean. These results will be useful for designing and applying management strategies for the reduction of $CO_2$ emissions.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.60 no.3
• /
• pp.374-380
• /
• 2015

This study firstly provides basic data for selection of cultivatable bioenergy grass in barren reclaimed lands applied with solidified sewage sludge. The experimental plots consisted of a plot containing reclaimed land mixed with solidified sewage sludge (MSS 50), a plot covered by solidified sewage sludge (CSS 100), and an original reclaimed soil plot (ORS). The growth, biomass production of bioenergy grasses and soil chemical properties were investigated in each experimental plot for 5 years. The organic matter (OM) and total nitrogen (T-N) content in both MSS 50 and CSS 100 were considerably higher than those in ORS. In bioenergy grasses, M. sacchariflorus cv. Geodae 1 showed an excellent growth and adaptability on reclaimed land applied with solidified sewage sludge. The application of solidified sewage sludge may provided soil nutrition in the reclaimed land due to the fact that bioenergy crops grew better in soils applied with solidified sewage sludge than in untreated soils, and treated soils had higher OM and T-N content than untreated soils. This study suggests that M. sacchariflorus cv. Geodae 1 is the most suitable biomass feedstock crop for biomass production and that solidified sewage sludge may be used as a soil material for cultivation of bioenergy grass on reclaimed lands.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.4
• /
• pp.475-483
• /
• 2012

Recently, agricultural lands decrease sharply, which was caused by urbanization, land consolidation, road construction, and innovation city construction, etc. In particular, Goyang, Chenan and Wonju city were had severe land use change. Therefore, we analyzed changes of land use, soil properties, and soil information in order to provide the basic soil information and soil management practice in these cities. The results are summarized as follows. The area of crop cultivated land in Korea (2011) was reduced to 17.3ha compared to ones from the previous year (2009). The paddy field decreased by 24.2 ha but, upland field increased by 7.0 ha. The reasons for the reduction of the paddy field were converting paddy field to upland (20.7 ha) > public facilities (3.2) ${\geq}$ building (3.2) > idle land (1.3) > and others (0.9). Other reasons for reduction in the upland field were switching upland to paddy field, (20.7 ha) > land developed (4.5) > and restoration (0.3) respectively. The main reason of converting paddy field to upland was changing from rice to more profitable upland or greenhouse crops. The cropland area (paddy fields, upland, orchard) of Goyang, Cheonan, and Wonju city were reduced to 1,466 ha, 9,708 ha and 6,980 ha respectively. The ratio of cropland area in each city was reduced by 45~25% dramatically compared to upland soil survey project in Korea (1995~1999). These data were compared with MiFAFF statistics data to use for land use cover map of Ministry of environment. But they were differences significantly. Therefore, intensive investigation should be advised throughout the utilization plan. The paddy fields located in small valley in Wonju city were changed into upland or orchard. The drainage classes of soil have been deteriorated because the flows of water were intercepted by road construction and other disturbance to water flows. In particular, paddy fields have been changed to not only upland, orchard, greenhouse cultivation but also to fallow and soil dressing on paddy in Wonju city. The soil suitability classes of paddy field in Wonju innovation city were the 3rd grade for 70.8% of the area and the 4th grade for 29.2%. The soil suitability classes of upland was the 4th grade for 88.7% of the area. Fortunately, good soil suitability classes were not belong to innovation city in Wonju. So, the good farm land should be conserved and revise the related law.

• Journal of Forest and Environmental Science
• /
• v.17 no.1
• /
• pp.1-17
• /
• 2001

Forming a part of "Cooperative Practical Study for the Modernization of the Management of National Forest", this study was conducted to provide overall ecological information for the natural regeneration of major tree species on the basis of community structural attributes in the deciduous forest ecosystem. Followings are summarized characteristics of the natural regeneration for the selected tree species. Betula costata : Although large number of seeds are dispersed by wind, they require mineral soils to germinate. Thick litter layer could be an obstacle to germinate. After germination, the seedling requires large amount of light for successful establishment. Acer mono : Characterized by high shade tolerance and weak drought resistance, the seedling should be overcasted with more than 50% of canopy coverage. High stand density should be maintained to produce good quality of timber. The potential of coppice may be high. Ulmus laciniata : Since this species needs high rate of troll moisture and light, around 60% of canopy coverage should be maintained to retain moisture and incoming light. The competition with other vegetation should be removed for the favor of successful seedling establishment. Fraxinus mandshurica : This species requires moist mineral soils to germinate. After germination, the seedling needs large amount of light and moisture for successful establishment. Site preparation should be applied to reduce competition with weedy vegetation. Fraxinus rhynchophylla : Interval of large seed crops may be highly varied. Thick litter layer could be an obstacle to germinate. Site preparation should be applied to reduce competition with weedy vegetation so as to achieve successful seedling establishment. Quercus mongolica : Including the difficulty of seed supply by the consumption, thick litter layer and mountain bamboo cover could be the obstacle to germinate. More than 50% of relative light intensity is necessary to achieve successful seedling establishment. Kalopanax pictus : Thick litter layer could be an obstacle to germinate. The seedling needs large amount of light and moisture for successful establishment. Abies holophylla : In spite of high shade tolerance, the growth rate in sapling stage may be extremely slow. Cornus controversa : Seeds (drups) are consumed and dispersed by animals, tending to be not sufficient in seed supply. This species requires large amount of light for successful germination and seedling establishment. Tilia amurensis : The difficulty of seed supply might be expected with low seed purity and double dormancy. Since thick litter layer could be an obstacle to germinate, the species requires moist mineral soils for successful germination. The potential of coppice may be extremely high.

• Korean Journal of Soil Science and Fertilizer
• /
• v.26 no.3
• /
• pp.172-180
• /
• 1993

Chemical properties of the soils were surveyed in the field of vinyl houses concentrated in the area of Bunpyong-dong and Shinchon-dong of Cheongju, Chilgeum-dong of Chungju and Gageum-myeon of Jungweon-gun. Chungcheongbuk-do province. 1. Content of chemical component of the soil in the vinyl house was higher than in open field. In more than half of the vinyl house soils surveyed, electric conductivity was more than 4.0 mmhos/cm and available phosphate was more than 1,000ppm. 2. Contents of availble phosphate and exchangeable potassium were increased with years of cultivation and their content of accumulation in soil were in the order of Bunpyong-dong>Shinchon-dong>Gageum-myeon>Chilgeum-dong. While their mobility was comparatively low. 3. $NO_3$-N content was remarkably higher in vinyl house soil and the older in cultivation made $NO_3$-N content higher same as the case of available phosphate content. However easy leaching of $NO_3$-N through soil profile is expected due to the fact that $NO_3$-N content was rapidly decreased by removal of polyethylene film cover from the frame of house after harvest of crops. 4. It is a tendency that various chemical contents of vinyl house soils wer higher in 1992 than in 1988~1990, especially much higher from the area of Bunpyong-dong and Shinchon-dong of Cheongju. 5. Salt accumulation in vinyl house soil has been increased with continuing cultivation. Therefore amount of fertilizer application should be controlled in order to avoid salt toxicity, quality deterioration for crop and salt contamination of ground water.