• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.201-206
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• 1999

For the mass production of plug seedlings in cultivar ‘Dejima’ potato (Solanum tuberosum L.) the optimal apical cutting diameter for rooting and rapid multiplication of stem cuttings in hydroponics were determined. In addition, the best planting date was predicted to increase tuber yield of plug seedlings at fall cropping in Cheju-Do, Korea. Days to initial rooting decreased as the cutting diameter was reduced. Plant height, leaf number, root length and root weight per plant were favorable as the cutting diameter was small. The ideal cutting diameter was 1-2 mm in this experiment. In the hydroponic cultures, the Japanese standard (JS) nutrient solution was the most effective for multiplication of stem cuttings. It was able to propagate more than 20 times a month from a single mother plant. Viability of plants, which were derived from plug seedlings using stem cuttings, was excellent when transplanted to the field. The number of tubers and tuber yield in both of the plug seedlings and seed potato planting plots were high when planted on 25 August. The number and yield were reduced when planted on 15 August, 5 September and 15 September. The degree of decrease of tuber yield in the plug seedling planting plot however, was lower than that of seed potatoes when the planting date was late. In the case of small tubers (under 30 g), the number of tubers and tuber yield were evidently increased in the seed potato tuber planting plot; the yield of large tuber (over 80g) in the plug seedling planting plot was higher than that of the seed potato. The total tuber yield per plant in the plug seedling planting plot was less than that of the seed potato; therefore, in order to increase tuber yield it was necessary to increase field plant density.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.1
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• pp.84-90
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• 1986

An experiment was conducted to know the effects of planting dates (March 5, 15, and 25 and April 4) and transparent polyethylene (P.E.) film treatments(tunnel, tunnel slit, and mulch) on air and soil temperatures and growth and yield of a sweet corn variety, Great Bell. Maximum air and soil temperatures and minimum air and soil temperatures were greater at tunnel>tunnel slit>mulch in that order. Differences in maximum air and soil temperatures among the P.E. film treatments were much greater than those in minimum air and soil temperatures. However, when film was opened due to high air temperature over 40$^{\circ}C$ in the tunnel, air temperature was similar but soil temperature was lower com-pared to mulch. High temperature stress could be avoided in tunnel slit without opening film by increase in the number of slits. Cold damage of corn seedlings was avoided by tunnel and reduced by tunnel slit, and frost-damaged seedlings under the mulch were recovered in few days. The number of days from planting to silking was reduced as planting date delayed. At early plantings, tunnel enhanced early growth and silking, but it delayed at late plantings because tunnel was opened during the most of day time due to high temperature. Black streaked dwarf virus(BSDV) disease was more severe at early plantings and it was reduced in tunnel slit at late plantings because plants were grown under the film at the time of infection. The number of marketable ears was similar among all treatments except mulch at March 5 planting where BSDV was severely infected. Gross income was high in tunnel and tunnel slit at March 25 planting which had more larger marketbale ears and tunnel and tunnel slit at March 5 planting which had higher market price.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.342-351
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• 1990

Experiments were conducted to find out the possibilities of producing good quality seed of summer type soybean at Chuncheon, 74m above sea level and Jinboo, 600m above sea level in 1987. Local variety, Cheonan Jaelae was used. Seeds were sown June 25 harvested five times from 35 days after flowering with five days interval to 55 days. Vegetative period was longer in the early planting and high cool area, Jinboo, which resulted longer stem length than the late planting and in the plain area, Chuncheon. Pod number and 100 grain weight were shown more and heavier in Jinboo. Earlier planting and later harvesting resulted more pod number and heaveier 100grain weight. Grain yield was heigher in Jinboo, and earlier plainting shown more grain yield and its difference was greater in Jinboo. Long grain filling duration resulted more grain yield. Unripened seeds were produced more by earlier planting with earlier harvesting and earlier planting with late harvesting showed the high rates of pod and stem blight (Diaporthe Phaseolorum). Seed With high moisture content by early harvesting showed more rotten seeds in all planting dates production was more advantageous in the high cool area, Jinboo. Optimum planting date was between May 15 and June 5. Harvesting was desirable about 45-50 days after flowering with heigher germination rate seed yield.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.4
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• pp.327-337
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• 1996

A field experiment was conducted at SNU Experimental Livestock Farm, Suweon in 1995 to determine effect of planting date on forage performance of wm hybrids of four different maturity groups. A split-plot design replicated three times was used, with com hybrids representing four maturity groups (115, 118, 121 and 125 days) being the main plots and planting dates (3124, 415, 415, 425, 515 and 5/15) the sub-plots. 1. Days to emergence and percent emergence from the March 24 planting were, on the average, 36 days and 58%, respectively, but those from the April 5 to May 15 planting averaged 12 days and 92%, respectively. 2. Plant and ear heights increased gradually as the dates of planting were delayed except the May 15 planting, however, percent ear was decreased as the dates of planting were delayed. There was a trend for the mean lodging percentage of the hybrids to be higher as the planting date was delayed. 3. The 115-and 118-day mediumearly maturing hybrids harvested on August 18 produced silages with a dry matter content between 27 and 30% at all planting dates except the May 15 planting, while the 121-and 125-day medium-late maturing hybrids produced silages with a dry matter wntent less than 27% regardless of any planting dates. 4. There were no significant differences in mean dry matter yield among the hybrids, but significant mean TDN yield differences were found. The 115-, 118- and 125-day hybrids had significantly higher mean TDN yield than the 121-day hybrid. There were significant differences in mean dry matter and TDN yields among the planting dates. The mean dry matter and TDN yields from the April 5, 15 and 25 plantings were significantly higher than those of other plantings, however, there were no significant differences in mean TDN yield among the April 5, April 15 and April 25 plantings. No significant planting date $\times$ maturity interactions were found for both the dry matter and TDN yields. 5. Mean stover NDF and ADF contents of the 115- and 118day hybrids were higher than those of the 121- and 125-day hybrids, but the reverse was true for mean stover IVDMD and RFV. Mean stover NDF an ADF contents increased with earlier plantings, but mean stover IVDMD and RFV increased when planting was delayed. Results of this experiment indicate that for corn planting in central and northern areas of Korea, early to mid-April may be the right time with the 115-to 118-day maturity hybrids when silage making before August 20 is taken into consideration.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.4
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• pp.272-275
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• 2000

Winter green manure crops including legume increase grain yield of subsequent crop and substitute N fertilizer requirement with organic-No Hairy vetch grows vigorously and can provide N-rich green manure for corn with its soil incorporation after wintering. But, grain yield of corn as succeeding crop would be reduced if its planting time is delayed until late spring. This experiment was carried out to find the proper incorporation time of hairy vetch green manure and planting time of subsequent corn in cropping system with winter hairy vetch(green manure)-summer corn. Hairy vetch was incorporated into soil at a ten-day interval between April 10 and May 10 and corn was planted at 5 days after each hairy vetch incorporation. Soil nitrate concentration on April 10 and 20 in hairy vetch plot was slightly lower than that at winter fallow. Above-ground dry matter and organic-N of hairy vetch increased linearly with delayed hairy vetch incorporation time from April 10 to May 10. Average dry matter and organic-N produced by hairy vetch were 5.7 ton/ha and 248 kgN/ha, respectively. Corn growth and yield decreased as delayed corn planting time after May in spite of increasing dry matter and N-yield of hairy vetch. Nitrogen concentration of corn grain, stalk and whole plant at harvest were the highest in May 5 planting, but total N-uptake of May 5 planting were not different from that of April 25 planting because of lower grain yield. It was concluded that the proper incorporation time of hairy vetch and corn planting time were April 20 and April 25, respectively, because grain yield was the highest and corn could use hairy vetch-N effectively to produce dry matter.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.959-963
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• 2010

This study was conducted to investigate the effect of planting dates using garlic bulbils for production of seed garlic. The planting dates were examined using 0.2 g bulbils of 'Namdo' or 'Danyang'. For the planting dates study conducted in the middle regions, the bulbils of 'Danyang' planted in autumn produced bulb weight ranging from 3.1 to 3.5 g and percentage of harvest ranged from 61 to 71. The bulbils of 'Danyang' planted in spring produced bulb weight ranging from 1.8 to 2.8 g and percentage of harvest ranged from 53 to 60. The most desirable planting date was in the early October for the middle regions. For the planting dates study conducted in the southern regions, the bulbils of 'Namdo' planted in autumn produced bulb weight ranging from 1.8 to 3.0 g and percentage of harvest ranged from 74 to 89. The bulbils of 'Danyang' planted in spring produced bulb weight ranging from 0.6 to 1.0 g and percentage of harvest ranged from 47 to 56. The most desirable planting date was in the mid and late September for the southern regions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.1
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• pp.47-55
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• 2020

This study was conducted to evaluate the flowering characteristics of 22 soybean (Glycine max Merrill) varieties of North Korea and classify the flowering group by the flowering date. The flowering date and the days required for flowering with the different planting times on May 31, June 19, June 30, July 3, and July 4 were investigated at the agricultural experimental field of Korea University for three years from 2017 to 2019. The flowering date and the days for flowering of "Yeonpungkong", an early maturing soybean cultivar of Korea, were July 18 and 48 days, respectively, at the planting time of May 31, those of "Daewonkong", a mid-late maturing cultivar, were July 30 and 60 days, respectively. Based on the flowering dates of "Yeonpungkong" and "Daewonkong", North Korean soybean varieties were classified into six flowering groups. Eight North Korean soybean varieties had the flowering dates earlier than "Yeonpungkong", including "Brekkhat" classified into the early flowering group. The range of flowering date was July 2 to 15 at planting time of May 31. Twelve North Korean soybean varieties had flowering dates similar to or later than "Daewonkong", including "Chang Dan Bac Mok" classified into the mid-late flowering group. The range of flowering date was July 24 to 30 at the planting time of May 31. For flowering response to environmental stimulus, all of the mid-late flowering varieties of North Korea responded to "photosensitive or day-length" for flowering reaction. The early flowering varieties were divided by "photosensitive" response and "temperature" response variety.

• Journal of The Korean Society of Grassland and Forage Science
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• v.30 no.1
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• pp.1-8
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• 2010

Few management studies have been conducted on late planting date for corn silage in paddy field as a barley-corn forage cropping system. Experiments were conducted during 2007 and 2008 at the Chungnam Agricultural Research & Extension Services. The objectives of this study were to determine relationships between planting date and com forage yield and to determine the best hybrid at the delayed planting after whole crop barley's harvest. The treatments consisted of 2 planting dates and 7 hybrids. Delayed planting considerately reduced stem diameter, individual ear size and weight. The ratio of dried leaf and culm in aerial plants was increased and that of ear was decreased. The coefficient of variation in fresh, dry matter (DM) and total digestible nutrients (TDN) yield was higher at delayed planting date on cropping system with whole crop barley than that of planting at optimum season. So, fresh weight was reduced by 91.8%, dry matter by 72.6%, grain yield by 51.0% and TDN yield by 68.1%. The appropriate hybrid for delayed planting after whole crop barley harvest in middle region was 'Gangdaok' as lower in the reduction of ear size and weight compared to that of planting at optimum season. Reduction in grain yield caused to decrease the DM and TDN yields. Therefore, to gain stable dry matter in silage corn by delayed planting date on cropping system with whole crop barley was necessary to select com hybrid on the minimum reduction in ear size and weight.

• Korean Journal of Medicinal Crop Science
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• v.28 no.2
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• pp.136-141
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• 2020

Background: The leaves of the goji berry (Lycium chinense Mill.) are used as raw materials in processing and by replace fruits to some extent. The reason is that the leaves are cheaper, however, betaine content is higher than in the fruits. These experiments were conducted to determine the planting density and cutting height for producing a large number of leaves. Methods and Results: The cultivar 'Myeongan' with many branches was used. When the shoot height reached 50 cm - 70 cm, harvesting was possible four times a year. The time to next harvest was approximately 38 days after regeneration of new shoots. Leaf quantity was in the order of 1st > 2nd > 4th > 3rd harvest. Insect damage occurred during the third harvest in late July and early August, therefore, eco-friendly control was necessary. The total yield was higher at the planting density 60 cm × 30 cm than that of 60 cm × 20 cm or 60 cm × 40 cm. The yield at cutting for shoot height of 60 cm was increased by 6.3 percent compared to that of 50 cm, At the cutting height of 70 cm, harvest was difficult owing to hardening of stems and thorns. Betaine content, an indicator component of goji berry, was not significantly different according to planting densities and cutting height. Conclusions: The ideal cutting period to produce leaves of goji berry for processing is when the shoots grow to approximately 60 cm, and the leaves can be harvested 4 times a year. The dried-leaf yield was highest at the planting density of 60 cm × 30 cm.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.3
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• pp.162-168
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• 2022

This study was carried out to investigate the effects of planting densities on the growth characteristics, dry matter yield, and feed value of "Geukdong 6" (a new variety of corn for feed). The experimental design was arranged in a randomized block design with three replications. Treatments consisted of six planting densities, 60 cm × 25 cm (T1), 60 cm × 30 cm (T2), 70 cm × 25 cm (T3), 70 cm × 30 cm (T4), 80 cm × 25 cm (T5) and 80 cm × 30 cm (T6). All treatments were sown on May 14, 2021, and the harvest was on October 3 (late flowering). Plant length and the number of tillers were the highest in T5 (p<0.05), but the number of leaves and stem diameter were the highest in T6 than in the other treatments (p<0.05). Leaf length, leaf width, and dead leaf were not significantly different among the treatments. Organic matter was highest in T6, and crude protein was highest in T5 (p<0.05). The ether extract was not significantly different among the treatments. Crude fiber, NDF, and ADF were highest in T2 with relatively higher planting density (p<0.05). Calcium and phosphorus were not significantly different among the treatments. TDN content was the highest in T3 (p<0.05). Sugar degree (Brix), fructose, glucose, dextran, isomerose, and inverted sugar were not significantly different among the treatment. Fresh yield, dry matter yield and TDN yield were higher in order of T6 > T5 > T4 > T3 > T2 > T1 (p<0.05). Relatively feed value was higher in order of T3 > T6 > T5 > T1 > T4 > T2 (p<0.05). Based on the above results, planting density could be recommended from 80 cm × 30 cm for efficient production of "Geukdong 6".