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Prediction of Chinese Cabbage Yield as Affected by Planting Date and Nitrogen Fertilization for Spring Production (정식시기와 질소시비 수준에 따른 봄배추의 생육량 추정)

  • Lee, Sang Gyu;Seo, Tae Cheol;Jang, Yoon Ah;Lee, Jun Gu;Nam, Chun Woo;Choi, Chang Sun;Yeo, Kyung-Hwan;Um, Young Chul
    • Journal of Bio-Environment Control
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    • v.21 no.3
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    • pp.271-275
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    • 2012
  • The average annual and winter ambient air temperatures in Korea have risen by $0.7^{\circ}C$ and $1.4^{\circ}C$, respectively, during the last 30 years. The continuous rise in temperature presents a challenge in growing certain horticultural crops. Chinese cabbage, one most important cool season crop, may well be used as a model to study the influence of climate change on plant growth, because it is more adversely affected by elevated temperatures than warm season crops. This study examined the influence of transplanting time, nitrogen fertilizer level and climate parameters, including air temperature and growing degree days (GDD), on the performance of a Chinese cabbage cultivar (Chunkwang) during the spring growing season to estimate crop yield under the unfavorable environmental conditions. The chinese cabbage plants were transplanted from Apr. 8 to May 13, 2011 when 3~4 leaves were occurred, at internals of 7 days and cultivated with 3 levels of nitrogen fertilization. The data from plants transplanted on Apr. 22 and 29, 2012 were used for the prediction of yield as affected by planting date and nitrogen fertilization for spring production. In our study, plant dry weight was higher when the seedlings were transplanted on 15th (168 g) than on 22nd (139 g) of April. There was no significant difference in the yield when plants were grown with different levels of nitrogen fertilizer. The values of correlation coefficient ($R^2$) between GDD and number of leaves, and between GDD and dry weight of the above-ground plant parts were 0.9818 and 0.9584, respectively. Nitrogen fertilizer did not provide a good correlation with the plant growth. Results of this study suggest that the GDD values can be used as a good indicator in predicting the top biomass yield of Chinese cabbage.

Determination of Optimum Heating Date for Off-Season Production of Asparagus (Asparagus officinalis L.) (단경기 아스파라거스 생산을 위한 적정 가온시기 구명)

  • Seong, Ki Cheol;Kim, Chun Hwan;Lee, Jin Su;Eum, Yong Chul;Moon, Doo Kyong
    • Journal of Bio-Environment Control
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    • v.21 no.3
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    • pp.276-280
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    • 2012
  • This study was conducted to determine the ideal beginning date of plastic house optimum heating for off-season (December) production of asparagus. To achieve this, the 1.6-year-old 'Green tower' asparagus was cultivated in Jeju area ($33^{\circ}$28.110N, $126^{\circ}$31.076E) and the yield and quality among 7 different beginning dates of heating from Oct. 25 to Jan. 20 with 15-days interval were compared. The heating was controlled to maintain the inside temperature was higher than $20^{\circ}C$, But the plastic house was ventilated when the inside temperature rose to $30^{\circ}C$. Days to sprouting took longer as heating dates were delayed. Days to sprouting took 52 days in heating at December 30, and the days were shortened thereafter. As the beginning of heating was delayed, sprouting of asparagus was retarded. Among treatments, days to sprouting was 52 days and longest when the heating began on December 30. When the heating began on October 25, harvest was earliest and started on 7 November. When the heating began on November 15 and 30, harvest started on November 30 and December 18, respectively. Harvesting started on November 7 for October 25 heating, November 30 for Nov. 15 heating, and December 18 for November 30 heating, respectively. When the heating began was done after December. 15, harvesting was possible after early January. The number of spear, spear weight and yield were highly increased in the treatments of heating after January. 10 when the asparagus dormancy was broken. In the case of heating dates were before the asparagus dormancy breaking, the total yield was highest in November 15 heating with 607 kg/10a. The marketable yield of November 15 heating was 386kg/10a, which was twice higher than the 193 kg/10a of October 25 heating. Accordingly, it is recommended to start heating on November 15 for the production of off-season (December) asparagus in Jeju. Therefore, the optimum heating date to start was November 15 for the improvement of quality and yield of off-season (December) asparagus in Jeju area.

Photosynthetic Characteristics and Chlorophyll Content of Rhododendron micranthum by the Natural Habitat (자생지에 따른 꼬리진달래의 광합성 특성 및 엽록소 함량)

  • Kim, Nam-Young;Lee, Kyeong-Cheol;Han, Sang-Sub;Lee, Hee-Bong;Park, Wan-Geun
    • Journal of Bio-Environment Control
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    • v.21 no.2
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    • pp.147-152
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    • 2012
  • This study was conducted to investigate the photosynthetic R. micranthum by natural habitats. In the results, natural habitats didn't affect values of light saturated point, light compensation point and photosynthetic capacity of R. micranthum. We investigated light response curve and chlorophyll content at each habitat. Light compensation points were 11.8 ${\mu}mol\;m^{-2}\;s^{-1}$, 11.5 ${\mu}mol\;m^{-2}\;s^{-1}$ and 10.4 ${\mu}mol\;m^{-2}\;s^{-1}$ in Seokpo-ri, Yeonha-ri, and Mt. Worak. Light saturation points showed that R. micranthum is shade tolerant specie which has the light saturation point approximately 500~600 ${\mu}mol\;m^{-2}\;s^{-1}$. Photosynthetic rates of R. micranthum leaves were 5.5 ${\mu}mol\;m^{-2}\;s^{-1}$, 5.4 ${\mu}mol\;m^{-2}\;s^{-1}$ and 5.6 ${\mu}mol\;m^{-2}\;s^{-1}$ in Seokpo-ri, Yeonha-ri and Mt. Worak. On the other hand, since between $20^{\circ}C$ and $30^{\circ}C$, it appeared that the values of net photosynthetic rates of R. micranthum leaves in all sites were high. Especially, the rates were highest at $25^{\circ}C$. Because of low stomatal transpiration rate in saturation radiance, the moisture utilization efficiency in Yeonha-ri was lower than other habitats. Rates of chlorophyll a, chlorophyll b, and total chlorophyll content in Mt. Worak were no significant difference. Therefore R. micranthum has characteristic of shade tolerant species. The moderate temperature for R. micranthum is between $20^{\circ}C$ and $30^{\circ}C$.

Heating Performance of Hot Water Supplying System in Greenhouse (온수배관을 이용한 온실의 난방성능)

  • Yoon, Yong-Cheol;Shin, Yik-Soo;Kim, Hyeon-Tae;Bae, Seoung-Beom;Choi, Jin-Sik;Suh, Won-Myung
    • Journal of Bio-Environment Control
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    • v.21 no.2
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    • pp.79-87
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    • 2012
  • This research was conducted to obtain basic data with regard to the heating performance that would be produced by installing an aluminum hot water pipe inside the greenhouse with the goal of reducing the heating energy in greenhouse. The research results are summarized as follows. The degree of difference in relation to the temperature by height within the greenhouse during the entire experiment was significant - within the range of 4.0~$7.0^{\circ}C$. The temperature difference between incoming and outgoing water was about $3.3^{\circ}C$ greater when FCU was activated compared to when it was not activated. Meanwhile, the amount of energy consumed increased about 36.2~40.1%. The amount of pyrexia per hour also increased by 44.6~52.0%. During the experiment period, circulated flux was within the range of 0.48~$0.49L{\cdot}s^{-1}$ while average fluid speed was 1.53~$1.56m{\cdot}s^{-1}$. The average temperature difference between incoming and outgoing water was 6.24~$11.50^{\circ}C$. The amount of heating value by each set temperature within the minimum outdoor temperature range of -14.0~$-0.6^{\circ}C$ was 135,930~307,150 kcal, and the range was within the 9,610~$19,630kcal{\cdot}h^{-1}$ per hour. This demonstrated that about 23~53% heating energy of the maximum heating load could be supplied. Total radiating value and amount of energy consumed were 2,548,306 kcal and 3,075.7 kWh, respectively. When heating takes place using oil, which is a fossil fuel, the total amount of light oil consumed was 281.6 L while the cost was 321,000 won. When the electricity cost for farms is applied, the total cost was about 110,730 won, which is about 33.5% of the cost required compared to oil consumption. The temperature at in the experiment area was about 8.3~$14.6^{\circ}C$ higher compared to that of the control area.

Physico.chemical Properties of Peatmoss and Coir Dust Currently Used as Root Medium Components for Crop Production in Korean Plant Factories (국내에서 식물공장용 배지 재료로 유통되는 피트모스와 코이어 더스트의 물리.화학적 특성)

  • Shin, Bo Kyoung;Son, Jung Eek;Choi, Jong Myung
    • Journal of Bio-Environment Control
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    • v.21 no.4
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    • pp.362-371
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    • 2012
  • Objective of this research was to secure the information on physical and chemical properties of peatmoss and coir dust. To achieve this, 6 kinds of peatmoss and 10 kinds of coir dust currently used in the country as the root medium components in plant factories were collected and analysed. The mean ${\pm}$ standard deviation (SD) of total porosity and container capacity in peatmoss and coir dust were $79.6{\pm}5.04$ and $83.6{\pm}6.18%$, and $69.9{\pm}10.17$ and $65.9{\pm}3.46%$, respectively. These indicate that peatmoss has higher water holding capacity than coir dust and the characteristics are highly varied among peatmoss. The 4 out of 5 kinds of peatmoss had lower than 10%, but coir dust had 12~26%, of air-filled porosity. The percentage of easily available water and buffering water in peatmoss and coir dust was 18~22 and 11~16% and 9~13 and 5.5~7.5%, respectively. These results indicate that precise irrigation is required when coir dust is used as the root medium. The ranges of pH and electrical conductivity (EC) were 3.46~4.17 and $0.137{\sim}0.253dS{\cdot}m^{-1}$ in peatmoss and 5.31~6.48 and $0.250{\sim}0.1.580dS{\cdot}m^{-1}$ in coir dust. However, $0.563{\pm}0.83dS{\cdot}m^{-1}$ in mean ${\pm}$SD of coir dust EC indicates that it is higher than that of peatmoss, and the coir dust are highly varied in EC. The cation exchange capacity of peatmoss was 3 to 4 times as high as that of coir dust. The coir dust had higher $NO_3$ and $PO_4$ and lower $NH_4$ than peatmoss. The K and Na concentrations in coir dust were extremely high indicating that these ions caused the rising in EC. The percentage of hot water and alkali extracts of peatmoss were 6.67~16.37 and 0~38%, whereas those of coir dust were 30.0~65.1 and 23.1~70.3%. These results mean that possible existence of growth inhibiting materials in coir dust.

Effect of Shading Methods on Growth and Fruit Quality of Paprika in Summer Season (파프리카 여름재배시 차광방법이 생육과 과실특성에 미치는 영향)

  • Ha, Jun Bong;Lim, Chae Shin;Kang, Hyo Yong;Kang, Yang Su;Hwang, Seung Jae;Mun, Hyung Su;An, Chul Geon
    • Journal of Bio-Environment Control
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    • v.21 no.4
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    • pp.419-427
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    • 2012
  • This study was carried out to investigate the effect of two shading methods, shading agent spray on the glasshouse and internal shading screen treatment, on the growth and fruit quality of paprika (Capsicum annuum L. 'Cupra' and 'Coletti') in summer season cultivation. In the shading agent treatment, a commercial shading agent diluted with water at a ratio of 1 : 4 was sprayed on the roof of a glasshouse. In the internal shading screen treatment, a 10~20% shaded screen was used during the day time when the sun radiation was greater than $700W{\cdot}m^{-2}$. Compared to the unshaded control, photosynthetic photon flux density (PPFD) decreased in the greenhouse in the shading agent (SA) and shading screen (SS) treatments by 20% and 30%, respectively. Lower air temperatures and higher relative humidities were observed in the SA than in both the control and the SS treatment. Time to reach the break point of humidity deficit $8g{\cdot}m^{-3}$ was 2 hours late in the SA than in both the control and the SS treatment. Compared to control, both the SA and the SS treatments showed lower instantaneous temperatures of leaf, fruit, and flower by $2^{\circ}C$, $5^{\circ}C$ and $3^{\circ}C$, respectively. There were no differences in number of branches, stem diameter, and leaf size among treatments although both shading treatments promoted plant height in both cultivars. Botrytis infection ratio declined with the SA treatment by 14.7% in 'Cupra' and 22.1% in 'Coletti' as compared to that in the control. Shading increased fruit size in both cultivars, whereas no differences were observed in the number of locules and thickness of fruit tissue among treatments. Shading treatment increased mean fruit weight by a range of 10 to 15 g per fruit, while it decreased soluble solids contents as compared to that in the control. Similar Hunter values were observed among treatments, while fruit firmness increased slightly in shading treatments. Compared to the control, shading treatments improved marketable fruits by 11.7~22.6% and increased the number of fruits per plant by 4~9.2 in both 'Cupra' and 'Coletti'. The results of this study indicate that shading agent application on the roof of glasshouse would be one of the most effective options to reduce heat stress imposed on the paprika crop in summer cultivation, resulting in improved crop growth and fruit yield.

Effects of Different EC in Nutrient Solution on Growth and Quality of Red Mustard and Pak-Choi in Plant Factory (식물공장내 양액의 EC가 적겨자와 청경채의 생육 및 품질에 미치는 영향)

  • Lee, Sang Gyu;Choi, Chang Sun;Lee, Jun Gu;Jang, Yoon Ah;Nam, Chun Woo;Yeo, Kyung-Hwan;Lee, Hee Ju;Um, Young Chul
    • Journal of Bio-Environment Control
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    • v.21 no.4
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    • pp.322-326
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    • 2012
  • Recently, researches related to plant factory system has been activated and production of Ssam-vegetables using artificial lighting has been increasing. In South Korea, Ssam-vegetables are very popular and the consumption is increasing every year. Because leaf vegetables cultivated under hydroponic systems are more preferable rather than those cultivated by soil culture in Korea, the plant factory system would be more effective in production of Ssam-vegetables. Therefore, this study was carried out in order to analyze the yield and vitamin C contents in red mustard (Brassica juncea L.) and pak-choi (Brassica campestris var. chinensis), which are used a lot for the Ssam-vegetables in South Korea, as influenced by different concentrations of the nutrient solution in a plant factory system. As a results, there was no significant differences in the plant height among the treatment of EC in the nutrient solution, but for red mustard plants, the number of leaves tended to decrease in the treatment with higher EC. Leaf area of pak-choi plants was significantly increased in the higher EC, while the fresh weight had a tendency to increase along with increasing EC in the nutrient solution for both crops. The photosynthetic rates did not show a distinct tendency by EC levels for red mustard plants, but for pak-choi plants, it tended to be higher at the high EC. The contents of ascorbic acid in leaves were higher with decreasing EC concentration in the nutrient solution for red mustard plants, while the content was the highest at EC $2.0dS{\cdot}m^{-1}$ for pak-choi plants. In summary, considering the marketable yields and vitamin C at different nutrient concentrations in a plant factory, the optimal concentration for red mustard and pak-choi plants was thought to be EC $2.0{\sim}2.5dS{\cdot}m^{-1}$.

Evaluation of Fruit Quality during Shelf-life at High Temperature Environment in 'Wonhwang' and 'Whasan' Pears ('원황' 및 '화산' 배의 숙도별 고온유통환경에서의 품질 평가)

  • Lee, Ug-Yong;Oh, Kyoung-Young;Choi, Jin-Ho;Hwang, Yong-Soo;Choi, Jong-Myung;Chun, Jong-Pil
    • Journal of Bio-Environment Control
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    • v.20 no.3
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    • pp.233-240
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    • 2011
  • We evaluated the changes of fruit quality factors and the incidence of physiological disorders during the periods of high temperature environment in 'Wonhwang' and 'Whasan' pears to determine appropriate harvest time for exportation. In 'Wonhwang' pears, the fruits harvested at 130 days after full bloom (DAFB) showed 31.3 and 17.6N of flesh firmness after 5 and 10 days after simulated marketing at $30^{\circ}C$, respectively, while those of the fruits harvested at 135 DAFB lowered to 16.7 or 6.9N, respectively. Whereas, 'Whasan' pear showed higher firmness during 14 days of high marketing condition than 'Wonhwang' pears which represented 30.4, 26.5 and 21.6N in the fruits harvested 145, 150 and 155 DAFB, respectively. Higher soluble solid contents and lower acidity values observed in the late harvested fruits in both cultivar along with increased marketing period at $30^{\circ}C$. Late harvested 'Wonhwang' pears showed higher respiration rate and ethylene production than early harvested ones, while those of 'Whasan' pears showed lower values regardless of fruit maturity which represented less than 50% of 'Wonhwang' pears. The incidence of physiological disorders such as internal browning, water soaking, flesh spot decay, core breakdown and pithiness appeared more severely in the fruits of 'Wonhwang' in accordance with the progress of high temperature marketing and fruit maturity. Whereas, those symptoms were occurred only after 14 days of prolonged marketing time in 'Whasan' pears. Consequently, it was needed to pay more attention to determine the ripeness when the fruits exported to the country with high temperature environment, especially in the fruits of 'Wonhwang' pears showing rapid quality loss and severe physiological disorders.

Development of Fertilizer-Dissolving Apparatus Using Air Pressure for Nutrient Solution Preparation and Dissolving Characteristics (공기를 이용한 양액 제조용 비료용해 장치 개발 및 용해특성)

  • Kim, Sung Eun;Kim, Young Shik
    • Journal of Bio-Environment Control
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    • v.21 no.3
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    • pp.163-169
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    • 2012
  • We have conducted three experiments to develop a fertilizer-dissolving apparatus used in fertigation or hydroponics cultivation in order to decrease the fertilizer dissolving time and labor input via automation. All of the experiments were conducted twice. In the first experiment, four selected treatments were tested to dissolve fertilizers rapidly. The first treatment was to dissolve fertilizer by spraying water with a submerged water pump, placed in the nutrient solution tank. The water was sprayed onto fertilizer, which is dissolved and filtered through the hemp cloth mounted on the upper part of the nutrient solution tank (Spray). The second treatment was to install a propeller on the bottom of the nutrient solution tank (Propeller). The third treatment was to produce a water stream with a submerged water pump, located at the bottom of the tank (Submerged). Finally, the fourth treatment was to produce an air stream through air pipes with an air compressor located at the bottom of the tank (Airflow). The Spray treatment was found to take the shortest time to dissolve fertilizer, yet it was inconvenient to implement and manage after installation. The Airflow treatment was thought to be the best method in terms of the time to dissolve, labor input, and automation. In the second experiment, Airflow treatment was investigated in more detail. In order to determine the optimal number of air pipe arms and their specification, different versions of 6- and 8-arm air pipe systems were evaluated. The apparatus with 6 arms (Arm-6) that was made of light density polyethylene was determined to be the best system, evaluated on its time to dissolve fertilizer, easiness to use regardless of the lid size of the tank, and easiness to produce and install. In the third experiment, the Submerged and Arm-6 treatments were compared for their dissolving time and economics. Arm-6 treatment decreased the dissolving time by 8 times and proved to be very economic. In addition, dissolving characteristics were investigated for $KNO_3$, $Ca(NO_3)_2{\cdot}4H_2O$, and Fe-EDTA.

Comparison of Wetting and Drying Characteristics in Differently Textured Soils under Drip Irrigation (점적관개 시 토성별 습윤.건조 특성 비교)

  • Kim, Hak-Jin;Son, Dong-Wook;Hur, Seung-Oh;Roh, Mi-Young;Jung, Ki-Yuol;Park, Jong-Min;Rhee, Joong-Yong;Lee, Dong-Hoon
    • Journal of Bio-Environment Control
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    • v.18 no.4
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    • pp.309-315
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    • 2009
  • Maintenance of adequate soil water content during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement for precision irrigation would allow efficient supply of water to crops, thereby resulting in minimization of water drainage and contamination of ground water. This research reports on the characterization of spatial and temporal variations in water contents through three different textured soils, such as loam, sandy loam, and loamy sand, when water is applied on the soil surface using an one-line drip irrigation system and the soils are dried after the irrigation stops, respectively. Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30cm depths. Spatial variability in water content for each soil type was strongly influenced by soil textural class. There were big differences in wetting pattern and the rate of downward movement between loam and sandy loam soils, showing that the loam soil had a wider wetting pattern and a slower rate of downward movement than did the sandy loam soil. The wetting pattern in loamy sand soil was not apparent due to a low variability in water content (< 10%) by a lower-water holding capacity as compared to those measured in the loam and sandy loam soils, implying that the rate of water drainage below a depth of 30cm was high. When soils were dried, there were highly exponential relationships between water content and time elapsed after irrigation stops ($r^2$${\geq}$0.98). It was estimated that equilibrium moisture contents for loam, sandy loam, and loamy sand soils would be 17.6%, 6.2%, and 4.2%, respectively.