• Proceedings of the Korean Society of Crop Science Conference
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• 2001.05a
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• pp.190-191
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• 2001

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1997.12a
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• pp.88-98
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• 1997

This study was conducted to develope the gripper of a robotic transplanter for bedding plants. Specific objectives of this study were 1) to develope the gripper for plug tray seedlings and 2) to find the suitable finger type for transplanting. The performance of gripper was tested and compared by two different transplanting methods, which were to consider the leaf position of seedlings and not to consider. The results of this study are summarized as follows. (1) The gripper of a robotic transplanter was developed and tested with 4 different finger type. (2) The shovel type finger was suitable for transplanting with the least percent of damaged seedlings.

• Journal of Bio-Environment Control
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• v.23 no.3
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• pp.199-204
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• 2014

This study evaluated the effect of water content in the substrate during pre- and post-grafting period on the survival rate and quality of tomato plug seedlings. Nine combinations of three water levels (high, medium, and low) were set up in the substrate of both scion and rootstock. The water content in the substrate of the scion did not affect the survival rate of grafted tomato seedlings, while the survival rate was statically different among the various water contents in the substrate of the rootstock. The maximum survival rates (100%) were observed in seedlings treated with high water levels in the substrate of the rootstock, and the survival rates declined with decreasing water content in the rootstock substrate. The growth characteristics were not significantly affected by different water content in the scion substrate, while they were statically different among the seedlings treated with various water contents in the rootstock substrate. The growth characteristics decreased with decreasing water content in the rootstock substrate. The highest value of compactness was observed in grafted seedlings, which combined medium water level in the scion and high water level in the rootstock substrate treatment. The root morphology of tomato seedlings was also affected by water content in the rootstock substrate. The total root surface area, total root length, and number of root tips decreased with deceasing water content in the rootstock substrate.

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.2
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• pp.59-69
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• 2019

This study was carried out to investigate effects of soil water content on growth and antioxidative enzymes activity of tomato seedlings during the nursery period. The water stress significantly damages morphological, physiological, and biochemical activities in plants. The seedlings planted with soil on the tray were irrigated and categorized into 3 groups with 30 g, 40 g, and 50 g of plant-soil weight. After then, the changes in weight of the soil and the seedling were measured evey 2 hours for 4 days and the leaf temperature was measured with the thermal-camera at the same time. The antioxidant enzymes were measured to determine the level of stress using all of the seedling samples. The result showed that the decrease of soil weight in the day time was faster than that in the night time, but there was no significant difference in the weight loss of the seedlings and soil among the groups. However, the group with 50 g of wight showed the highest SOD and POD contents. This is considered that the continuously wet soil on the root zone of the seedlings caused more stress for the seedlings. Therefore, it is concluded that the excess moisture content causes stress to stimulate the secretion of antioxidant enzymes, and the effect of stress is required to be analyzed comprehensively using environmental data and also the physiological data that are collected over a longer period.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.379-387
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• 2007

This research was conducted to evaluate the influence of pre-planting fertilizer levels (PFL) and initiation time of fertigation (ITF) on growth and nutrient contents of tomato plug seedlings. The pre-planting fertilizer levels in a coir+peatmoss+perlite (4:4:2, v/v/v) substrate were adjusted to 0.5X, 1.0X and 1.0X, and initiation time of fertigation was set to 7, 14,21 and 28 days after sowing. Elevated PFL in same ITF increased plant growth such as fresh and dry weights at 35 and 70 days after sowing. Plugs with early feeding among treatments of equal amount of PFL also showed better growth as compared to those of later feeding. In each ITF, 0.5X treatment had the higher tissue $P_2O_5$ contents than 1.0X and 1.5X treatments. Elevated PFL resulted in the decrease of tissue K, Mg and Fe contents and increase of tissue Ca contents. The pH in soil solution of all root substrates except 0.5X treatment at 35 and 70 days after sowing were greater than 7.0, which is too high. This suggests that the amounts and kinds of Ca containing fertilizers should be altered to decrease the pH. The results of this research indicated that fertilizer levels should be increased to 1.5X except Ca fertilizer, and fertigation immediately after moving plug trays from germination room to greenhouse is required to increase crop growth and decrease cropping time.

• Journal of Biosystems Engineering
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• v.29 no.3
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• pp.251-260
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• 2004

As a basic experiment for robot hand for transplanting plug seedling, the experimental robot hand system which moves up and downward vertically, and allows hand blade to open and close was made. The system was constructed with the robot hand mechanism, the tray, the plug seedling, and the measuring equipments. The penetrating force and holding efficiency were analyzed according to the soil moisture and the variation of hand blade angle. The highest holding efficiency could be obtained at the penetrating angle of approximately from 0 to 0.36 degree and at the moisture content of soil from 71% to 75%. The external force acted on the robot hand should maximum force when the robot hand was penetrated to soil, minimum of approximately 30.4 N when the penetrating angle was 0$^{\circ}$ and moisture content was 66-70%. It was increased with increasing or decreasing the Penetrating angle from 0 degree and also with increasing or decreasing the moisture content of soil from 66-70%. For optimal design of the robot hand and manipulator, the external force acted on robot hand had to be based on the returning force of soil, when the robot hand was penetrated to the soil. In consideration of safety ratio, the appropriate external force seemed to be 39-49 N.

• Journal of Bio-Environment Control
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• v.12 no.3
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• pp.166-172
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• 2003

Rockwool slabs used for hydroponic cultures are expected to have potential to be reused after breakdown as a growing medium component for hydroponic culture of vegetables and cut flowers, pot plants, or plug plants. This study was conducted to test the feasibility of using particles of used rockwool slabs (PURS) mixed with woodchips for growing plug seedlings of ‘Nokkufang’ pepper. In the first experiment growth of pepper seedlings was tested in media of steam sterilized PURS mixed with chestnut woodchips (CW), which was weatherized for six months and screened through 2.8 mm or 5.6 mm sieves, at 100:0, 75:25, 50:50, 28:75 or 0:100 (%, v/v). In the second experiment growth of pepper seedlings was tested in 20 different media containing steam sterilized PURS mixed with 4 mm chestnut woodchips (CW), 4 mm pinc woodchips (PW), coir, peatmoss, or perlite. In the first experiment, there were no significant growth differences as affectcd by particle size of CW, while the overall best growth was achieved il1 the control and l00% PURS. In the second experiment, seedling growth was enhanced as compared to the control in 100% PURS or PURS mixed with peatmoss, coir, or perlite. In contrast, growth was suppressed as the proportion of peatmoss or coir mixed with PURS decreased and the proportion of CW increased. Growth was better in the PURS + peatmoss than in the 100% PURS or PURS + coir, and when woodchips were mixed with coir than peatmoss.

• Horticultural Science & Technology
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• v.18 no.1
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• pp.33-38
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• 2000

This study was conducted in an effort to meet the need for domestic production of hydroponic media and for medium development using recycled hydroponic rockwool slabs. Two experiments were conducted to evaluate the growth of plug seedlings of petunia 'Romeo' in various mixtures including particles of used rockwool slabs (rockwool particles) and wood chips. In the first experiment, seedlings were grown in plugs filled with mixtures of steam- sterilized rockwool particles and chestnut wood chips, which had been weathered for six months and screened through either 2.8 mm or 5.6 mm sieve, at the mixing ratio of 100:0, 75:25, 50:50, 25:75, or 0:100 (v/v). In the second experiment, seedlings were grown in plugs filled with twenty different mixtures of steam-sterilized particles of used hydroponic rockwool slabs with 4 mm chestnut or pine wood chips, coir, peatmoss, or perlite. In the first experiment seedling growth was not affected by particle size of chestnut wood chips, was superior in the control (commercial plug medium) and in 100% rockwool particles, but was suppressed as mixing ratio of chestnut wood chips increased. In the second experiment, leaf length, and shoot fresh and dry weights were the greatest in rockwool particles+peatmoss+coir treatment, followed by rockwool particles+peatmoss treatment. Leaf length was suppressed as ratio of wood chips increased, especially of chestnut wood chips. Root development was the greatest in rockwool particles+peatmoss+perlite treatment, followed by the control, and rockwool particles+peatmoss+coir treatment. The growth was suppressed as the mixing ratio of rockwool particles, peatmoss, or coir decreased.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.160-166
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• 1996

Objective of this study was to investigate the effects of all current speed on the microclimates above and inside the plug stand under artificial light. Maximum air temperature appeared near the top of the plug stand. Difference in air temperature inside the plug stand increased with the decreasing air current speed. Difference in relative humidity(DRH) to the relative humidity at the Inlet of the main air flow conditioner Inside and above the plug stand decreased with the increasing air current speed. Relative humidity inside the plug stand was 10-15% higher than that above the plug stand. DRH inside a stand of plug at air current speed of 0.3m s$^{-1}$ was about two times as many as that at air current speed of 0.9 m s$^{-1}$ . DRH inside the plug stand was 2.8-6.5% higher at LAI of 2.6 than that at LAI of 0.5. Gradient for the vapour pressure deficit was distinctly appeared at the low air current speed. Direction of vapour pressure flux is from the medium surface upwards. Difference in vapour pressure(DVPD) to the vapour pressure deficit at the inlet of the main air flow conditioner inside and above the plug stand decreased with the increasing height above the medium surface. DVPD inside the plug stand was 0.3-0.4㎪ higher at air current speed of 0.9m s$^{-1}$ than that at air current speed of 0.3m s$^{-1}$ . Results for the effects of air current speed on the relative humidity and vapour pressure deficit indicated that the microclimates above and inside the plug stand at the rear region in plug trays were slightly unfavorable compared to those at middle region.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.616-625
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• 2016

This research was conducted to investigate the optimum level of nitrogen incorporated during formulation of root media as pre-plant fertilizer on the growth of plug seedlings of 'Bool-am No.3' Chinese cabbage. A root medium was formulated by blending peatmoss:coir dust:perlite at a ratio of 3.5:3.5:3.0 (v/v/v). The nitrogen was incorporated in the seven treatments at a rate of 0, 100, 250, 500, 750, 1,000, and $1,500mg{\cdot}L^{-1}$ during the root medium formulation. The concentrations of other essential nutrients except nitrogen were controlled to equal in all treatments. Then, the root medium was packed into 72-cell plug trays and seeds were sown. The growth measurements as well as tissue and soil solution analysis for nutrients were conducted 2 and 4 weeks after seed sowing. As seedlings grew, the pH in the extracted solution of all treatments tended to decrease. The decreases in the treatments of high N concentrations were more severe than those with low N, but the differences among treatments were not statistically significant. The differences of EC in extracted solution of root media among treatments were sizable until week 3, but the differences began to lessen and the EC decreased in all treatments after week 4. Growth of the aerial parts of plug seedlings at 2 weeks after sowing were highest in the $100mg{\cdot}L^{-1}$ and lowest in the $1,500mg{\cdot}L^{-1}$ treatments, but those at 4 weeks after sowing were highest in the $500mg{\cdot}L^{-1}$ and lowest in the $0mg{\cdot}L^{-1}$ treatments among all treatments tested. The tissue N content was highest and lowest in the treatments of 250 and $1,000mg{\cdot}L^{-1}$, respectively, when tissues were harvested at 4 weeks after sowing and analysed based on the dry weight of above-ground tissue. The contents of micronutrients were the highest in the 1,000 and $1,500mg{\cdot}L^{-1}$ treatments among all treatments. The results shown above indicate that the $250mg{\cdot}L^{-1}$ of pre-plant N and elevation of post-plant N concentration to above $100mg{\cdot}L^{-1}$ are suitable for raising plug seedlings of Chinese cabbage using inert media.