• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.3
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• pp.143-150
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• 2003

This study was conducted to determine the response of main growth characters, yield and chemical composition of Jeju native soybean based on the difference between phosphate rates (0, 50, 100, 150, 200, 250kg/ha) from May 11 to September 10 in 2002 in Jeju island. Days to flowering was delayed from 92 days to 97 days as the increasing of phosphate rate. Also plant height grew longer from 109cm to 124cm. The number of branches and leaves, stem diameter, root length and weight of root grew powerful as phosphate rate increased from 0 to 250kg/ha. Fresh forage yield was 26.5MT/ha in the nonphosphate plot and then was 36.9MT/ha as phosphate rate increased to 250kg/ha. And the difference between 200kg/ha and 250kg/ha in phosphate rate was not significant. Dry matter, crude protein and TDN yield increased 6.0∼7.9MT/ha, 0.9∼1.4MT/ha and 3.4∼4.9MT/ha respectively, as the increasing of phosphate rate. Also crude protein, crude fat, NFE and TDN content increased 15.5∼18.3%, 2.2∼3.3%, 42.5∼43.5%, and 56.7∼61.9% respectively. In contrast with this, crude fiber and crude ash decreased 32.1∼28.1% and 7.7∼6.8% respectively. To reach the climax of forage yield was estimated optimum phosphate rate to be 200kg/ha.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.3
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• pp.135-142
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• 2003

Jeju native soybean was grown at five plant densities(30${\times}$30cm, 30${\times}$25cm, 30${\times}$20cm, 30${\times}$15cm, 30${\times}$10cm) from May 11 to September 10 in 2002 in Jeju island to determine the optimum plant density. Days to flowering was delayed from 94 days to 98 days as increasing of plant density. Plant height was 103cm at 30${\times}$30cm plot, as plant density increased, was 117cm at 30${\times}$10cm plot. As plant density increased, the number of branches and leaves, stem diameter, weight of plant, root length and weight of root grew low. As plant density increased from 30${\times}$30cm to 30${\times}$15cm, fresh forage, dry matter, crude protein and TDN yield increased 23.3∼36.5MT/ha, 5.1∼8.0MT/ha, 0.8∼1.4MT/ha and 2.9∼4.8MT/ha respectively, but decreased at 30${\times}$10cm plot. As plant density increased, crude protein, crude fat, NFE and TDN content increased 16.2∼17.9%, 2.7∼3.7%, 37.6∼40.7% and 56.1∼60.0% respectively. In contrast with this, crude fiber and crude ash decreased 34.9 ∼30.8% and 8.6∼7.2% respectively. To reach the climax of forage yield was estimated optimum plant density to be 30${\times}$15cm.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.1
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• pp.62-66
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• 1984

One row of pollen parent to two rows of seed parent (1:2), 2:4 and solid (1:2) planting patterns (PP) were compared in seed parent densities of 3,500, 5,000 and 6,500 plants per 10 ares to determine effects of PP and plant density on growths of seed and pollen plants, and seed yield of seed parent of modified single cross corn hybrid. Planting pattern did not significantly affect agronomic characteristics of seed plant except ear number per 100 plants and seed yield which were greater in solid and 1:2 PP than in 2:4 PP. Significant PP x plant density interaction did not exist for agronomic characteristics of seed parent. In the seed parent, plant height and 100 kernel weight were not affected by plant density, but ear height, ear number per 100 plants, and kernel number per ear were linearly decreased with increased plant densities. Seed yield ranged from 330 to 460 kg per 10 ares and overall yield response to plant density was quadratic. Tassel length and spikelet number per tassel of the pollen parent were significantly affected by PP and plant density. Significant PP x plant density interaction existed for tassel length and spikelet number per tassel. Tassel length and spikelet number per tassel were greater in 1:2 and 2:4 PP compared to solid PP and were greatly reduced with increased plant densities in solid and 1:2 PP. The results indicated that 1:2 or 2:4 PP at around 5,000 plants per 10 ares for seed parent would be suitable for seed production of modified single cross com hybrid.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.4
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• pp.481-487
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• 1983

The need to synchronize flowering in two lines of different maturities is frequently encountered in hybrid com (Zea mays L.) seed production. To establish the methods for synchrony of flowering in parent lines of different maturities be effects of clipping at 4 and 6-leaf stages of growth and two levels, clear polyethylene mulching and five different planting dates on flowering date growth and seed yield of two dent com inbred lines of different maturities were evaluated Clipping just above the shoot-apex delayed pollen sheeding 6 to 9days and silking 5 to 13 days but reduced stand and seed yield 30 to 70% and 67 to 81%. respectively. Clipping 5cm above the shoot apex delayed flowering 1 to 4 days without stand reduction but reduced yield 3 to 29%. Laterclipping was slightly more effective for delaying flowering than earlier clipping but reduced stand more severely when clipped just above the shoot apex. Under clear polyethylene film mulching, flowering of two lines was 13 to 15 days earlier and seed yield of B68 (late line) was significantly increased. As planting was delayed from April 18 to June 13, the number of days from planting to flowering of two lines decreased due to increase in air temperature. However, growing degree days (GDD) from planting to flowering of each lines was similar regardless planting dates indicating that GDD can be satisfactoryly used for choosing the planting dates of parent lines of different maturities. Seed yields of two lines were decreased with delaying planting dates.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.2
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• pp.227-232
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• 1983

Two single cross maize hybrids planted on May 4 and 25 and June 15, 1982 were grown at 40,000:55,000 70,000 and 85,000 plants per hectare to evaluate plant density effect on growth and grain yield at different planting dates. Two hybrids with different leaf angle (Suweon 19 with horizontal leaves and Suweon 58 with erect leaves) and the same maturity were used. The number of days from planting to silking varied from 74 to 58 days as planting was delayed from May 4 to June 15. However, growing degree days from planting to silking was about $810^{\circ}C$ regardless planting dates. Grain yields of two hybrids were significantly decreased as planting was delayed. The number of ears per 100 plants and the number of kernels per ear of two hybrids were linearly decreased with increasing plant density. The optimum plant density for Suweon 19 estimated by Duncan's method was about 55,000 plants hectare for May 4 and 25 plantings and decreased to 32,000 plants/hectare for June 15 planting. The optimum density for Suweon 58 was estimated to be about 71,000 plants/hectare for May 4 planting and 54,000 plants/hectare for May 25 planting, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.143-150
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• 1998

In order to evaluate the nitrogen (N) balance, from the different application methods and levels of $^{15}N$ applied to a satsuma mandarin orchard soils in spring, we surface-applied N as urea at the rates of 50 (water-dissolved), 100 (solid and water-dissolved) and 150% (solid) of the recommended rate ($180kg\;ha^{-1}$) in spring (lebeled N), summer (nonlebeled N) with application ratio of 5:2:3. Fruit yield and quality were not significantly affected by any treatment. Nitrogen contents of spring flush leaves in late August were 3.0% regardless of the treatments. The N recovery by parts of tree itself was in the order of leaves, fruits, roots, stems, and the highest recovery per tree was 22.3% in the 50% recommended water-dissolved surface broadcast while there were not much differences for N recovery (11.9 to 13.6%) among the other three treatments. Total N content in top 30cm of soils was 0.47% regardless of the treatments, but N proportion and total residual N from the fertilizer applied increased with increasing N rate while the N recovery in soils decreased. For the recommended N rate, N proportion and the residual N from the fertilizer applied were greater in the water-dissolved surface broadcast than those in soils surface broadcast. The highest total (tree + soils) N recovery was 70.9% in the 50% recommended water-dissolved surface broadcast, but tended to decrease to 52.2, 46.6, and 43.2% for the recommended water-dissolved surface broadcast, 100 and 150% of the recommended solid surface broadcast, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.132-139
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• 1999

A field experiment was conducted at Cheju from early March 1998 to early March 1999 to evaluate the effects of foliar applied urea on leaf N content and N recovery in satsuma mandarins (Citrus unshiu Marc.). Seven years old 'Okitsu Wase' trees received foliar spray of urea (22 or 43 g N $tree^{-1}yr^{-1}$) or soil application of urea (86 g N $tree^{-1}yr^{-1}$). 56% of N was applied in spring, 11% in summer and 33% in fall. There were seven trees per N treatment and two trees per N treatment received $^{15}N$-labeled urea in spring and summer to determine N recovery. There were no differences between the treatments for fruit yield and its quality. Nitrogen content of spring flush leaf blades up to early September was greater for trees received foliar spray comparing with soil application but was not greatly affected by any treatment after mid-November. The recovery of fertilizer N in various parts of trees receiving foliar spray of 22 g N $tree^{-1}yr^{-1}$ was greatest, followed by receiving foliar spray of 43 g N and soil application of 86 g N. The recovery of fertilizer N in tree was 29.2 and 17.7% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, respectively and 8.0% for soil application of 86 g N $tree^{-1}yr^{-1}$. The recovery of fertilizer N in the upper 40 cm of soil was 50.3, 45.6, and 51.8% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, and soil application of 86 g N $tree^{-1}yr^{-1}$ respectively. The total (tree, fallen leaves, winter weeds, and soil) recovery of fertilizer N was 81.8, 65.1, and 60.6% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, and soil application of 86 g N $tree^{-1}yr^{-1}$, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.4
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• pp.408-421
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• 1989

The effects of seeding and clipping termination dates, and seeding and fertilizer rates on forage and grain yields were evaluated in 1989 harvest year for dual production of forage and grain of naked and malting barleys in Cheju province. In the experiment I, 'Saessalbori' (naked barleY)1 and 'Doosan 22' (malting barley) were seeded on Sept. 21, Oct. 12 and Nov. 2, respectively. An unclipped(grain-only) treatment that was planted on Nov. 2 was included for check. In the experiment II, the two above cultivars were planted at seed rate of 14, 20 and 26 and kg/l0a. Fertilizer rates were 9-6-12, 17-13-8 and 22-16-11 (N-P$_2$O$\sub$5/-K$_2$O) kg/l0a. Seeding dates were Oct. 13 and Nov. 7 for clipped treatments and grain -only treatment(seeding rate: 14kg/l0a, N-P$_2$O$\sub$5/-K$_2$O=9-6-12 kg/l0a), respectively. All treatments in both experiments were harvested for grain yield. In Saessalbori, survival following forage removal was 100％ regardless of seeding and clipping termination dates, and seeding and fertilizer rates. In Doosan 22, survival percenage decreased with increasing seeding and fertilizer rates when plants was clipped in January to Febuary. Forage yield of two cultivars increased with early planting and delays in clipping termination and tended to increase as seeding and fertilizer rates were increased. Crude ash and fat were not affected by seeding and fertilizer rates, and clipping date. Crude protein increased with an increase in fertilizer rate and decreased with delays in clipping date. N free extract tended to increase with delaying clipping date and decreased with increasing fertilizer rate. Earlier planting resulted in earlier heading and maturity. Clipping slightly delayed heading of Saessalbori and greatly delayed that of Doosan 22. Maturity of Doosan 22 was delayed 3 to 5 days by increased fertilization. Clipping shortened culm length more severely in Doosan 22 than in Saessalbori. The later the clipping termination, the shorter the culm length. The number of spikes per m$^2$ and the number of kernels per spike were not affected by clipping in Saessalbori while those of Doosan 22 were decreased with delays in clipping termination. Delaying forage harvest resulted In a reduction in grain yield. However, final clipping on Feb. 27 reduced grain yield of Saessalbori by only 6-11 ％ compared to the grain-only treatment. In Doosan 22, forage harvest after Dec. 28 resulted in 6 to 66％ reduction of grain yield. The data indicate that grazing of naked and malting barleys until late Feb. and late Dec., respectively, might not reduce grain yields when planted on mid-Sept. to mid-Oct.

• Journal of The Korean Society of Grassland and Forage Science
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• v.25 no.2
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• pp.125-130
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• 2005

This study was conducted from March 16 to July 6 in 2004 at Jeju Island to investigate the influences of sowing dates(on March 16, March 26, April 5, April 15 and April 25) on creeping bentgrass vegetation. The result obtained were summarized as follows; Plant height was 22.7 cm at March 16 planting. It was longest but after that planting, plant height gradually shorted. Then it was shortest at April 25 planting(16.6 cm). Root length and Minolta SPAD-502 chlorophyll reading value were directly proportional plant height response. Leave and root weight were greatest at March 16 planting. It were 1,373 kg /10a and 2,374 kg /10a, respectively. These weight decreased gradually as planting was delayed from March 16 to April 25. Degree land cover and density of creeping bentgrass were $98.0\%$ and $99.3\%$, respectively, at March 16. After that planting they were decreased ($97.5\%$, $98.7\%$). But degree land cover and density of weed tended to increased gradually as the planting was delayed. The number of weed species were increased from March 16 to April 25. It showed increase that Poa annua, Stellaria media and Chenopodium album var. centrorubrum(at March 16 planting), Poa annua, Digitaria adscendens and Chenopodium album var. centrorubrum(at March 26 planting), Digitaria adscendens, Chenepodium album var. centrorubrum and Stellaria media(at April 5 planting), Digitaria adscendens, Stellaria media and Chenopodium album var. centrorubrum(at April 15 planting), Digitaria adscendens, Polygonum hydropiper, Chenopodium album var. centrorubrum(at April 25 planting). Based on the these findings, optimum sowing date for growth of creeping bentgrass seems to be about early seeding in atmospheric phenomena and volcanic ash soils of Jeju island.

• Journal of The Korean Society of Grassland and Forage Science
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• v.25 no.2
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• pp.131-136
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• 2005

This study was conducted from March 21 to July 7 in 2004 at JeJu Island to investigate the influences of seed-ing rates (4, 6, 5, 10 and 12 kg/10a) on creeping bentgrass vegetation. The result obtained were summarized as follows; plant height was getting longer as seeding rate increased from 4 to 12 kg/10a, Although it was no significance from 10 to 12 kg/10a. Root length, Minolta SPAD-502 chlorophyll reading value, leave and root weight increased as the plant height increased. The degree of land cover and density of creeping bentgrass also increased as seeding rate increased from 4 to 12 kg/10a, and the degree of land cover and density of weed decreased. The number of weed species on decreased as increasing of seeding rate. Then ranking of the dominant weeds were Digitaria adscendens, Chenopodium album var. centrorubrum md Poa annua (at 4 kg/10a seeding rate), Digitaria adscendens, Chenopodium album var. centrorubrum and Stellaria media (at 6 kg/10a seeding rate). Chenopdium album var. centrorubrum, Poa annua and Digitaria adscendens (at 8 kg/10a seeding rate), Digitaria adscendens, Chenopdium album var. centrorubrum and Steilaria media (at 10 kg/10a seeding rate), Chenopdium album var. centrorubrum, Digitaria adscendens and Stellaria media (at 12 kg/10a seeding rate). These results showed that the optimum seed-ing rate is 10 kg/10a for growth of creeping bentgrass in volcanic ash soils of Juju island.