• Journal of Korean Society of Forest Science
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• v.95 no.4
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• pp.501-506
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• 2006

To study the regeneration process of tree species after clear cutting, we investigated the density of seedling occurred after 1 year in the coniferous forest of Sikotuko Hokkaido, northern Japan that was clearcut after windthrow damage due to typhoon. As the results, 25 species of tree seedlings were growing and the density of seedlings and sprouts was $9.8trees/m^2$ ($1.25tres/m^2{\sim}54.44trees/m^2$) in the area of clear cutting. The 87% ($8.6/m^2$) of all seedlings was current seedlings and non-animal dispersal seedlings (average density $7.2tree/m^2$) were about 5 times more than animal-dispersal seedlings ($1.4tree/m^2$). The seedling density was beyond $6tree/m^2$ within 10m and $2{\sim}9tree/m^2$ in 150~250m from a natural forest. Number of non-animal dispersal seedlings were decreased along the distance from a natural forest but there was not such a tendency in animal dispersal seedlings. The variation in seedling density was higher in non-animal dispersal seedling than in animal dispersal seedling. In natural regeneration of tree species after clear-cutting, the possibility that pioneer species like Betula spp. etc. will be composed of the major species is high. Therefore, in order to maintain the species diversity, the nurture work for reducing competition among the individuals is necessary.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.2
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• pp.204-213
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• 1986

The objective of this paper was to examine the response of rice seedling emergence and early growth under the different temperature (day/night, 29/21$^{\circ}C$, 17/17$^{\circ}C$, 12/12$^{\circ}C$) and the different seeding depth (1 cm, 2 cm, 3 cm). The trial was carried out in the phytotron and field in the Crop Experiment Station, Suwon, Korea in 1985. Calcium peroxide-coated seeds were very effctive in promoting seedling emergence, seedling establishment and eary growth of rice. Coated seeds were more effective in low temperature condition (17/17$^{\circ}C$, 12/12$^{\circ}C$) than in high temperature (29/21$^{\circ}C$) at the phytotron trial. The deeper the seeding depth, the less the emergence and seedling establishment, and the available seeding depth was I cm in the direct seeding under the flooded soil. In the field trial (seeding date, May 1) the results for the emergence and seedling establishment were similar to those in the phytotron trial. Available cultivars for the direct seeding cultivation under the flooded soil were Cheonmabyeo, Namyangbyeo, Kihobyeo, Akibare, Nakdongbyeo and Dongjinbyeo in Japonica type, and Taebaegbyeo, Samgangbyeo and Gayabyeo in Indica x Jponica type. Coefficients of variation to the emergence and seedling establishment between rice cultivars were very high. Therefore, in the direct seeding cultivation under the submerged paddy, choice of rice cultivars and improved technique for direct seeding will be more necessary.

• Korean Journal of Agricultural Science
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• v.1 no.1
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• pp.9-26
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• 1974

1. Results in Nursery This experiment was carried out on the effect of the seed treament, soil preparations, kinds of covering soil and inside covering methods in two rice varieties, 'Tongil' and 'Akibare' to find out the most reasonable model of the flat nursery bed, with which lower cost is required comparing with the tunnel nursery. The results obtained are as follows: (1) The seedling of all plots of the ordinary seed were very poor compared to the plots of sprouted seed. (2) In case that the variety 'Tongil' was cultivated on the dry nursery bed, the good seedling percentage and the plant height rat io were significantly increased but the other characteristics of the seedling were not noticeable. (3) The kinds of the covering soil had not an effect on the seedling growth significantly. (4) Inside straw mulching was seemed effective for the protection in the case of the extreme high temperature and heavy rain fall, even though there was not significant differences between inside straw mulching and no treatments at the flat type nursery. (5) Difference of seedling growth between the flat type nursery and the tunnel type nursery was not significant. And it's reason was thought that the covering period of polyethylene film was short in semi hot nursery for the common early transplanting cultivation of rice. (6) The percentage of good seedling was higher at 'Akibare' than 'Tongil', variety but the number of seedling leaf and the seedling growth ratio in height were significantly increased in the variety 'Tongil'. The other seedling characters between there two varieties were not significantly different. 2. Results after transplanting This experiment was conducted to study on the ripening percentage, rice yield and disease, appearance of the seedling from sprouted seed plots including common irrigated nursery as check plot after transplantnig. The results obtained are summarized as follows: (1) The rice yield, the yield components and the appearance of leaf discoloration of both varieties, 'Tongil' and 'Akibare' were slightly betterat the plot of the standard tunnel nursery than that of the flat nursery with inside mulching or the among these three plots. (2) For 'Tongil' variety, the ripening percentage and the rice yield were significantly decreased at the common irrigated nursery compared with semi hot nursery. (3) The ripening percentage and the rice yield of 'Akibare' contrasted with 'Tongil' were significantly decreased at thesemi 'hot-nursery compared with common irrigated nursery. The main reason was thought to be the injury of the rice stripe disease (Rice stripe disease virus). Considering above mentioned experimental result, the seedling of 'Tongil' must be cultivated on the semi bot nursery for better ripening percentage as well as rice yield and for prevention of red discoloration. And as a model of semi hot nursery, the polyethylene covering nursery of standard tunnel type is most desirable but that of flat type with inside straw mulching is thought to be desirable too.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.181-188
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• 2020

This study was conducted to identify the optimal conditions for seedling growth in Veronica rotunda var. subintegra (Nakai) T.Yamaz. which a endemic plant and can be development as ornamental plants. We sowed V. rotunda var. subintegra (Nakai) T.Yamaz. seeds, and exposed the seedling was different treatment conditions. We varied soil type and fertilizer concentration, shading ratio, additional fertilizer concentration, pretreatment light exposure and collection time of seeds. We found that seedling growth was good in horticultural substrate (with no additional fertilizer), but mixed soils supplemented with fertilizer inhibited growth, regardless of the fertilizer concentration. In the 55% shading treatment, seedling growth was greater than in the non-shading treatment. High concentration addition of fertilizer (Hyponex) promoted plant growth, in terms of both plant length and fresh weight. Exposure of seeds to a red light-source prior to germination had a greater effect on seedling growth than exposure to other light sources. Seedlings exhibited better growth when grown from seed collected in 2018, rather than 2017.

• Journal of Biosystems Engineering
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• v.28 no.5
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• pp.395-402
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• 2003

Standard ginseng seedling, selected after one year's rearing in the seedling bed has been conventionally transplanted in Korea. Recently, the direct seeding areas have been increasing to product high quality ginsengs for red-ginseng processing. Reciprocating push-rod brush, holed-roller and vacuum suction seeders, planting with 30 ${\times}$ 30mm spacings and adjustable to the folds were designed and theirs performances were evaluated. The developed three types of seeders reliably performed at the success rate over 95% with less than 10% in slip rate, and could be used a seeder for the greater spacings by adjusting metering parts. The research concluded that the vacuum suction seeder was the most feasible and practical with the greatest metering success and the least slip among three type seeders of the reciprocating push-rod brush, holed-roller and vacuum suction seeders. The vacuum suction seeder holds a seed with each needle nozzle using the negative pressure created by a vacuum pump. The capacity was 24.5 times greater than a man power at the speed of 5 m/min.

• Journal of Biosystems Engineering
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• v.23 no.3
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• pp.259-270
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• 1998

An automatic seedling transplanter, employed an innovative plug-seedling feeder was developed by improving the problems of conversational feeding and transplanting mechanisms. With conventional methods, missing and damage rates of seedling were high for long seedlings over 20cm and also breaking seed-bed was frequently observed. Thus, a pushout-bucket slide-hopper type trandsplanter was devised and tested. Test results of picking and transferring accuracies of the developed transplanter are as follows : A prototype transplanter performed with 1.5% of missing rate. The deviations of horizontal feed ranged from -0.3mm to 2.8mm and averaged 0.673mm for the 128-hoe test tray : and ranged from -lmm to ＋3mm and averaged 0.785mm for the 200-hole test tray. The deviations could decrease with precise manufacturing and lightening the mechanism. The maximum and deviations of vertical feed were -2.3mm and + 1mm, respectively, for the 128-hole test tray ; and were ＋3mm and ＋2.5mm, respectively, for the 200-hole test tray. The missing rate, seeding bruise rate and seed-bed damage rate were esitmate to be 1.3％, 0.4% and 3.5％, respectively, with the developed automatic transplanter.

• Journal of Biosystems Engineering
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• v.26 no.5
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• pp.415-422
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• 2001

A seedling pick-up device for vegetable transplanters was developed and its work performance was evaluated at the laboratory. The pick-up device extracts seedlings from a 200-cell tray of seedlings and transfers them to the place where they are to be transplanted into the soil. The device consists of a path generator, pick-up pins and a pin driver. The path generator is a five-bar mechanism comprised of a fixed link, a driving link, a driven link, a connecting link and a slider. The slider is constrained to move along the driven link and a fixed slot of combined straight-line and circular paths. The connecting link joins the driving link and the slider. When the slider moves along the straight-line path of the slot it takes seedlings out from the cell and transfers them to the transplanting hopper when moving along the circular path. A proto-type of the pick-up device was built and tested under the various operational conditions such as age of seedling, approach direction and penetration depth of pins to the cell, holding method of seedling and extracting velocity. The device extracted 30 seedlings per minute with the maximum success ratio of 97% using the seedlings of 23 days old. Some design details were also discussed and suggested to enhance the performance of the device.

• Journal of Environmental Science International
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• v.33 no.5
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• pp.305-322
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• 2024

The aim of this study was to investigate the effects of artificial light sources on the germination and seedling vigor of lettuce, aiming to identify the optimal artificial light source for producing high-quality seedlings. Lettuce cultivar of 'Tomalin' and 'Seonpunggold' exhibited the highest seed emergence in the Metal halide(MH) lamp and High-pressure sodium(HPS) lamp treatment group, while the emergence rate parameter, T50, was the fastest in the HPS lamp treatment group. Both cultivars showed good growth characteristics such as number of leaves, root length, and stem diameter under RGB-LED, and their seedling vigor was excellent as well. The plant height was smallest in the Red + Green + Blue LED treatment, but the leaves were round and thick, resulting in higher biomass and dry weight. Single light sources of Red LED and Blue LED led to reduced growth compared with that under the mixed light treatments. Chlorophyll content in lettuce varied with the type of artificial light, with both cultivars exhibiting the highest chlorophyll content in the Red + Green + Blue LED treatment. The most suitable artificial light for lettuce seedling growth was the Red + Green + Blue LED treatment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.147-151
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• 2003

Normal seed tubers and plug seedlings raised from stem cutting and mini-tubers ($10\pm3$ g) were planted or transplanted on August 20,2001 in bare soil or under transparent and black polyethylene film mulches to evaluate the effects of mulch material and seedling type on the growth and tuber yield of fall-grown potato (Solanum tuberosum L. cv. Dejima) in Jeju region. Total tuber number per plant was 4.6 regardless of mulch treatment, and direct planting seed potatoes resulted in the greatest tubers (5.14)/plant and followed by transplanting seedlings raised from cutting and mini-tubers (4.15 and 5.15 tubers/plant). Transparent and black polyethylene film mulches increased total tuber yield by 16 and 8%, respectively, and average tuber weight by 14 and 12%, respectively, compared with no mulch (21.16 t/ha and 72.2 g/tuber). Transplanting plug seedlings raised from cutting resulted in the greatest tuber yield, followed by transplanting plug seedlings raised from mini-tubers and direct planting seed potatoes.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.111-111
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• 2017

The development and productivity of maize (Zea mays L.) is frequently impacted by water scarcity, and consequently to increased drought tolerance in a priority target in maize breeding programs. To elucidate the molecular mechanisms of resistance to drought stress in maize, RNA-seq of the public database was used for transcriptome profiling of the seedling stage exposed to drought stress of three levels, such as moderate, severe drought stress and re-watering. In silico analysis of differentially expressed genes (DEGs), 176 up-regulated and 166 down-regulated DEGs was detected at moderated stress in tolerance type. These DEGs was increasing degradation of amino acid metabolism in biological pathways. Six modules based on a total of 4,771 DEGs responses to drought stress by the analysis of co-expression network between tolerance and susceptible type was constructed and showed to similar module types. These modules were discriminated yellow, greenyellow, turquoise, royalblue, brown4 and plum1 with 318, 2433, 375, 183, 1405 and 56 DEGs, respectively. This study was selected 30 DEGs to predicted drought stress response gene and was evaluated expression levels using drought stress treated sample and re-watering sample by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). 23 genes was shown increasing with drought stress and decreasing with re-watering. This study contribute to a better understanding of the molecular mechanisms of maize seedling stage responses to drought stress and could be useful for developing maize cultivar resistant to drought stress.