• Journal of The Korean Society of Grassland and Forage Science
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• v.3 no.2
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• pp.86-91
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• 1983

The harvest schedule for maximum total yield and quality of orchardgrass sward was studied on the basis of theoretical analysis due to Chang's total yield equation. Harvesting at the 10% bloom stage of morphological development of orchardgrass swards was selected as a criterion which provided highest dry matter (DM) yield in conjunction with high and consistent levels of in vitro dry matter digestibility (IVD) and crude protein contents (CP) from harvest to harvest. However, since orchardrass after the 1st cutting do not bloom, the harvest time for the maximum yield and quality of orchardgrass swards is replaced by the three should time of the ceiling leaf area index (LAI).

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.99-100
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• 2022

화학산업이 발전함에 따라 잠재적인 화학물질 폭발사고 위험 또한 증가하고 있다. 순식간에 치명적인 인명, 재산피해를 남기는 폭발에 대한 영향을 예측, 분석하기 위해 다양한 해석모델이 활용되고 있지만, 폭발의 물리적 특성상 다양한 형태의 건물이 밀집된 지역에 대해서는 해석모델 사용만으로 높은 정확도의 분석을 진행하기에는 어려움이 있다. 따라서 본 연구는 GIS 공간정보와 3D 폭발 시뮬레이션의 약결합 방식을 적용하였다. 실제 연구지역과 동일한 환경을 구현하여 시뮬레이션을 구동하였고 이에 따른 폭발 규모와 폭발에 노출된 대상별 가해지는 압력 값을 도출하였다. TNT를 기준으로 위험물 저장 및 취급시설에 대한 최저 기준인 지정수량 200kg을 적용하였음에도 최대 2,960kPa의 압력이 발생하는 것으로 확인되었다. 본 연구로 도출된 결과에 건축물의 용도와 중요도를 적용한다면 토지이용계획 및 공간활용에 반영할 수 있으며, 안전관리자로 하여금 리스크 평가, BC분석, 안전관리계획 수립 등에 활용 가능하다고 사료된다.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.448-454
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• 2021

This study was conducted to the effect of low air temperature and light intensity conditions on yield and quality of tomato at the early stage of growth in Korea. Inplastic greenhouses, low temperature and low temperature with shade treatments were performed from 17 to 42 days after plant. Tomato growing degree days were decreased 5.5% due to cold treatment during the treatment period. Light intensity decreased 74.7% of growing degree days due to shade. After commencing treatments, the plant growth decreased by low temperature and low radiation except for height. Analysis of the yield showed that the first harvest date was the same, but the yield of the control was 3.3 times higher than low temperature with shade treatment. The cumulative yields at 87 days after transplanting were 1734, 1131, and 854 g per plant for control, low temperature, and low temperature with shade, respectively. The sugar and acidity of tomatoes did not differ between treatment and harvesting season. To investigate the photosynthetic characteristics according to the treatment, the carbon dioxide reaction curve was analyzed using the biochemical model of the photosynthetic rate. The results showed that the maximum photosynthetic rate, J (electric transportation rate), TPU (triose phosphate utilization), and R_d (dark respiration rate) did not show any difference with temperature, but were reduced by shading. Vcmax (maximum carboxylation rate) was decreased depending on the low temperature and the shade. Results indicated that low temperature and light intensity at the early growth stage can be inhibited the growth in the early stage but this phenomenon might be recovered afterward. The yield was reduced by low temperature and low intensity and there was no difference in quality.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.1
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• pp.53-59
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• 1986

The effects of soil moisture on seasonal changes of photosynthesis, transpiration and stomatal resistance were studied in sorghum (Pioneer 931) and sorghum - sudangrass hybird (Pioneer 988) at Suweon in 1985. Soil moisture was maintained with approximately 100, 80, 60 and 40% of field moisture capacity in large concrete pot (12m length $\times$ 1m width $\times$ 1m depth). 1. Photosynthesis and transpiration showed a sharp seasonal changes and reacted similarly to water stress and environmental factors, and were the highest in the middle of August, and were the lowest in the beginning of October. Sorghum - sudan hybird had better photosynthesis, transpiration and stomatal control than those of sorghum in hot summer season. 2. The rate of photosynthesis of 60 and 80% field moisture capacity was higher than that of 100 and 40% throughout growing season, but the effect of soil moisture on photosynthesis varied seasonally by climate factors. Optimum soil moisture was 60% in early summer and fall, and was 60 - 80% in hot summer season. 3. Drought and over-moisture affected physiological metabolism of plant, and so the dry matter yield of 40 and 100% field moisture capacity decreased by 70% compared with that of 60% field moisture capacity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.2
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• pp.144-150
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• 2014

Yams (Dioscorea spp), which are edible or medicinal tuber crops, are a important crop in South Korea. Yams require a high level of soil fertility. The various cultural practices such as fertilizing and plowing were tested for marketable tuber production in Chinese yam (Dioscorea opposita). Tuber yield was also affected by organic matters in soil. Application higher level of organic matters result in increased each tuber weight and tuber yield per unit area. The nutrient absorption quantity of the plant such as nitrogen, phosphoric acid, calcium and potassium was increased from 100~120 days after planting, which time to begin tuber enlargement. The tuber yield was increased when the fertilization increased in quantity. Total yield and marketable ratio were the highest in 31~32 kg/10a of nitrogen fertilizer. From above result, income become larger with increase of marketable yield and quality improvement at 63% (27 kg/10a) level of conventional N fertilization (43 kg/10a). The tuber yield was not significantly different between with in various application level of potash fertilizer. Tuber size and weight decreased accordingly to decreased fertilizing level, so the rates of small tubers increased greatly at cultivation without chemical fertilizer. In considering the accumulation rates of allantoin in Chinese yam tubers, the apt harvest season was after October. The allantoin quantity of it was not influenced with nitrogen fertilizing. Moreover it was advantageous with decrease of chemical fertilizer and appropriate fertilizing in soil environment protection. Commercial tuber's number and yield were increased in trenching before planting with trencher compared with rotavating with tractor.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.248-262
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• 1987

This experiment was conducted to study plant characteristics and dry matter production of several rice varieties. The results are summarized as follows. 1. Culm length was gradually shortened as varieties were improved and showed significant decrease in Japonica X Indica hybrids. 2. Panicle length seems to be shortened as varieties changed from group I to group III. However, varieties in group IV had longer panicle length in spite of shortening tendency in other groups. 3. Leaf blade length was decreased as varieties improved, but leaf blade width was increased. 4. Panicle exertion showed significant decrease as varieties improved. 5. Number of panicles per square meter among Japonica varieties was gradually increased and similar to the number of spikelets per panicle. Number of spikelets on Indica X Japonica hybrids were higher than Japonica varieties, whereas 1,000 kernel weight was slightly decreased. 6. Dry weight of leaf sheath and culm, and leaf blade was highest at the time of heading and the weight of panicle showed significant increase between 10 and 20 days after heading. 7. The maximum crop growth ratios of leaf blade, stem and panicles were attadined at the stage of heading, booting and milking, respectively. 8. The distribution ratio of dry matter was higher in leaf blade than in stem at the tillering stage. At the heading stage, the distribution ratio of dry matter was higher in order of culm, leaf blade and panicle. At the maturing stage, the ratio was higher in order of panicle, stem and laf blade. 9. Correlation coefficients among grain yield, harvest index, and biological yield were all significant and they were positive.

• Journal of The Korean Society of Grassland and Forage Science
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• v.43 no.1
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• pp.28-34
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• 2023

This experiment was carried out to determine effects of seed rate of native grasses, called native summer forage crops (NSFC), on their growth characteristics and yields in no-tillage paddy fields in central provinces. NSFC cultivation was performed according to the agricultural guidelines of the Rural Development Administration (RDA) during 2020 to 2022. Echinochloa crusgalli 'Jeju native', Setaria viridis 'Korean native type', Digitaria sanguinalis 'Korean native type') were sown by various seed rate in the experimental field (3m × 4m plot) of Department of Animal Resources Development, Seonghwan-eup, Cheonan, Korea in late-May or early-June for 3 years and harvested in middle-September. Dry matter yields (DMY) in Echinochloa crusgalli and Setaria viridis increased as increasing seed rate. DMY in 40 kg ha^-1 of Echinochloa crusgalli was the highest and DMY in 60 kg ha^-1 of Setaria viridis was the highest. However, All treatments of Digitaria sanguinalis showed similar DMY. Yields of NSFC were the order of Echinochloa crusgalli (9,681~11,092 kg ha^-1) > Digitaria sanguinalis (8,311~9,023 kg ha^-1) >etaria viridis (3,145~4,749 kg ha^-1). The contents of crude protein in NSFC were the order of Digitaria sanguinalis > Echinochloa crusgalli > Setaria viridis. The contents of ADF and NDF in NSFC were the order of Echinochloa crusgalli > Digitaria sanguinalis > Setaria viridis. As shown in above results, we suggest that introduction of NSFC is one of the most important skills in order to stably increase yields of forage crops for utilization of the double cropping system in no-tillage paddy fields.

• Korean Journal of Environmental Agriculture
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• v.3 no.1
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• pp.52-56
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• 1984

In order to evaluate the applicability of two kinds of antibiotic fermentation residues on rice and tomato growth, yield, yield components, and some indicators for plant growing status were checked including analysis of physico-chemical properties of these two antibiotic fermentation residues. The results obtained are as follows: 1) These two antibiotic fermentation residues contain high organic matter ($21.6{\sim}24.2%$), phosphorus ($2900{\sim}4600 ppm$) and exchangeable cations ($55.4{\sim}138.3 meq/100 g$,), showing their pH values of $7.0{\sim}8.0$ range. 2) Both have developed net positive charge rather high and stiffly that exhibits high negative ion adsorption capacities, accordingly showing higher zero point of charges($pH 7.0{\sim}8.0$) than those of common soils. 3) The effect of the two kinds of antibiotic fermentation residues on rice growth was more or less the same comparable to the effect of the other fertilizers applied, showing the maximum yield at the application rate of 40 ㎏/10a. 4) The effect of these antibiotic fermentation residues on tomato growth was also similar to effects on rice plant showing the yield increment upon fertilizer application including two antibiotic fermentation residues but no significant differences among fertilizers. 5) According to the plant growing status, plant height, dry matter, number of effective tillers and grain number per panicle of rice and plant height and fresh weight of plant of tomato showed similar trend with yield of both plants.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.292-299
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• 2022

This study was conducted to analyze physical and chemical properties of horticultural substrates and response of hydroponically grown two cultivars of 'Namcheon' and 'Somirang' perilla by four different substrates: coir (chip:dust = 5:5), perlite, granular rockwool, and commercial mixed substrate (cocopeat:peatmoss:vermiculite:perlite: zeolite = 50:25:10:10:5). There were no significant differences in EC and pH according to substrates. Container capacity was the greatest in granular rockwool, and it showed appropriate levels in mixed substrate and coir. Air space was higher in coir and perlite than the other treatments. Bulky density reached a proper standard in all substrates excepting coir. The leaf length and width of 'Namcheon' indicated the most in mixed substrate, though the value of 'Somirang'was greatest in coir substrate. The leaf weight of both cultivars was highest in mixed substrate, and relatively low in coir and perlite. The total yield of leaves was separated by two groups: higher group, which are mixed substrate and granular rockwool, and lower group, which are coir and perlite. There was a large gap by 28% between these two groups. Therefore, this study suggests that substrates with high water holding capacity such as mixed substrate or granular rockwool are most suitable for the hydroponic cultivation of perilla, which require sufficient moisture supply to the root zone.

• Journal of Bio-Environment Control
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• v.28 no.1
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• pp.9-15
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• 2019

This study aimed to examine the effects of different degrees of defoliation during harvest season on hydroponically cultured 'Seolhyang' strawberry's fruit characteristics, plant growth, and changes in nonstructural carbohydrates, and find an effective defoliation method. On November 29, 2013, some of the 'Seolhyang' leaves were non-defoliated and the others were defoliated remaining 9 and 5 leaves. The number of fruits and fruit weight were not significantly different in the first flower cluster but in the second, third, and fourth flower clusters decreased as the level of defoliation increased. The soluble solids content and acidity of fruits decreased in all the clusters as the level of defoliation increased. The leaf area and leaf dry weight of strawberry plant in all the treatment groups decreased from January to March and root dry weight sharply decreased during February. Thereafter, during April, the growth of plant increased. As defoliation increased, the dry weight of fruits, flower clusters, crowns, and roots decreased, and during late growing period, difference in dry weight according to the degree of defoliation was considerable. The content of carbohydrate was greater in the leaves than the fruits excepting January 30 and February 28, 2014 and in the case of strawberry plant that continuously produce fruits, the content of carbohydrate decreased in the leaves and roots. As defoliation increased, the content of carbohydrate in fruits, flower clusters, crowns, and roots decreased. Defoliation for strawberry plants is carefully done during harvest season. Twelve leaves during December and 14 leaves from January to March should be maintained, and in April when the number of leaves increases, old leaves should be defoliated.