• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.1
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• pp.1-6
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• 2003

This study was determined to the growth characteristic, yield and chemical content of Azuki bean(Vigna angularis W.F. $W_{IGHT}$) based on five phosphate rates (0, 40, 50, 120, 160, 200kg/ha) from May, 2002 to August, 2002 in Jeju province. Plant height was 80.7cm at 0kg/ha of phosphate level md, as phosphate rates were increased to 160kg/ha and 200kg/ha, lengthened 88.8cm and 88.9cm, respectively, but between the two phosphat levels were no significance(P＞0.05 or 0.0l). Numbs. of branches and leaves per plant, stem diameter, and weight of leaves and stems per plant were the same response with plant height. Fresh forage, dry matter, crude protein, and TDN(total digestible nutrient) yield at the control were 23.8MT/ha, 3MT/ha, 0.5MT/ha and 1.8MT/ha, respectively, at the 200kg/ha plot were 47.3MT/ha, 7.2MT/ha, 1.3MT/ha, and 4.7MT/ha, respectively, as phosphate rate was increased. As phosphate rate increased from 0kg/ha to 200kg/ha, the content of crude protein, crude fat NFE(nitrogen free extract) and TDN increased 15.2%~18.6%, 3.4%~4.5%, 41.4%~45.5% and 58.3%~65.5%, respectively, whereas the content of crude fiber and crude ash were decreased 31.5%~24.8% and 8.1%~6.6%, respectively.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.1
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• pp.7-12
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• 2003

This study was conducted to determine the influence of seeding date (May 3, 13, 23, June 2, 12) on the growth characteristics yield and feed value Azuki bean(Vigna angularis W.F. Wight) from May 3, 2002 to August 3, 2002 in Jeju province. Plant height was the longest (84cm) when seeded on 13 May and was the shortest (48.4cm) when seeded on 12 June. Numbers of branches and leaves per plant, stem diameter and weight of leaves and stems per plant were the same trend with plant height. Fresh forage, fry matter, crude protein and TDN(total digestible nutrient) yield per ha at were increased to 54.6MT, 7.7MT, 1.4MT and 4.5MT, respectively, whereas decreased as seeding date was delayed and then at seeding on 12 June were decreased to 11.5MT/ha 2.12MT/ha 0.4MT/ha and 1.3MT/ha, respectively The content of crude protein, crude fat, NFE(nitrogen free extract) and TDN were incresed 17.6%∼21.3%, 3.3%∼4.5%, 34.3%∼41.4% and 56%∼64.8%, respectively, as seeding was delayed from 3 May to 13 June. Whereas the content of crude fiber and crede ash were decreased 33.8%∼23.5% and 11%∼9.3％, respectively.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.459-469
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• 2015

The effects of elevated spring temperatures on the growth and fruit quality of the mandarin hybrid 'Shiranuhi' [(Citrus unshiu ${\times}$ C. sinensis) ${\times}$ C. reticulata] were investigated in plastic greenhouses, to develop a cropping system to improve the quality of the fruit and increase the income of growers on Jeju Island, South Korea. Under conditions of elevated temperature I ($25/15^{\circ}C$, day/night) and elevated temperature II ($28/18^{\circ}C$, day/night) during early spring, budburst was advanced by 11 and 15 d, and full bloom by 22 and 45 d, respectively, compared to those of the plants grown at ambient air temperature in a plastic greenhouse. Elevated temperatures decreased the number of spring shoots but increased mean spring shoot length and leaf area. Growing 'Shiranuhi' trees at elevated temperatures resulted in increases in mean fruit weight and fruit L/D ratio (> 1.0). In addition, fruit color development was significantly advanced in trees grown under elevated temperatures during early spring, which allowed the fruit to be harvested 1-2 months earlier than trees grown under ambient air temperature. Fruit soluble solids content (SSC) and titratable acidity (TA) at harvest were similar between elevated temperature I and ambient air temperature, but were significantly higher than at elevated temperature II. Considering fruit quality, harvest time, and yield, the elevated temperature treatment regime of $25/15^{\circ}C$ (day/night) during early spring could be useful for cultivation of the mandarin hybrid 'Shiranuhi' to increase the income of growers.

• Korean Journal of Environmental Biology
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• v.30 no.2
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• pp.98-106
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• 2012

The chlorophyll fluorescence and photosynthetic $CO_2$ fixation capacity of leaves from three major crop trees found on Jeju Island, Camellia sinensis L., Camellia japonica L., and Citrus unshiu M., were analyzed. The photosynthetic $CO_2$ fixation rate of C. sinensis was similar to that of C. unshiu, and much higher than that of C. japonica which belongs to the same genus. Stomatal conductance in the three species was high at dawn and low during daytime. The intercellular $CO_2$ concentration of the three species was also high at dawn and decreased at midday. The transpiration rate showed an opposite trend from the intercellular $CO_2$ concentration. The photochemical efficiencies of PSII (Fv/Fm) in C. sinensis were slightly lower at midday compared to the level at dawn and/or dusk. The decline in Fv/Fm of C. sinensis at midday was much smaller than that of C. japonica. These results indicate that C. sinensis is better acclimated to high levels of radiation under natural conditions in late summer, although its PSII reaction center was inhibited by strong radiation. Of the chlorophyll fluorescence parameters in the species, the RC/CS decreased significantly while the ABS/RC, TRo/RC, ETo/RC, and DIo/RC increased significantly at midday in late summer. However, C. unshiu did not show significant changes in these values depending on the time of day. Among the three species, the daily $CO_2$ fixation rate in C. sinensis ($320.1mmol\;m^{-2}d^{-1}$) was the highest, followed by that of C. unshiu ($292.5mmol\;m^{-2}d^{-1}$) and C. japonica ($244.8mmol\;m^{-2}d^{-1}$). Thus, C. sinensis may be a valuable crop tree in terms of the uptake of $CO_2$ under natural field conditions.

• Korean Journal of Environment and Ecology
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• v.30 no.2
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• pp.146-154
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• 2016

In this study, understanding the habitats on spot-billed duck that wintering-breed in the korea, which using the GPS-Mobile based Telemtry (WT-200), I tried to take advantage as the basic data of the protection and management of the habitats of the waterbirds of Korea. Study area is Gyeonggi-do Bokhacheon, Chonmichon, Chungcheongnam-do Gokugyochon, Chungcheongbuk-do Byeongcheoncheon, Jeollabuk-do Mangyunggang, which Five rivers and Jeju Island reservoir, I have attached the tracking of the location(WT -200) to the twenty-five spot-billed ducks. among twenty five ducks, twelve ducks moved to overseas countries, the arrival site was China, North Korea, Russia. Moving average distance was 683km, the largest distance was 1,238km. The average northbound starting date was April 26. The average daily movement distance of thirteen ducks remaining in the domestic country is $1.0{\pm}0.89km$, maximum travel distance was 23.8km. The average daily movement distance of wintering prior to average going north dating is a 0.9km, is the largest 14.6km, the breeding season is an average 1.3km, maximum was 14.4km. Spot-billed duck used the rivers in domestic country most frequently, following was rice field, a filed, reservoir. It used the river most frequently during the wintering period, in the breeding season it used paddy paddies most frequently. While wintering, during the day and night's utilization rate was the highest in the river, but utilization rate was incleased on filed, paddy filed at night. During breeding season, daytime and night's utilization rate was the highest but, utilization rate was increased on river and utilization rate was decreased on river. In accordance with time change, spot-billed duck showed different tendency in paddy fields, and they utilized the filed adjacent to rivers mostly.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.116-124
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• 2006

Remarkable winter season warming has been observed in East Asian countries during the last century. Accordingly, significant effects on dormancy and the resulting budburst of deciduous trees are expected. However phenological observations are rare and insufficient compared with the long-time climate records in the same region. A chill-day accumulation, which can be estimated from daily maximum and minimum temperature, is expected to make a reasonable proxy for dormancy depth of temperate zone fruit trees. To simulate dormancy depth during 1921-2004, a chill-day model parameterized for 'Campbell Early' grapevine, which is the major cultivar grown virtually anywhere in South Korea, was applied to daily temperature data at 8 locations in South Korea. The calculations showed that the chilling requirement for breaking endo-dormancy of this grapevine cultivar can be satisfied by mid-January to late February in South Korea, and the date was delayed going either northward or southward from the 'Daegu-Jeonju' line crossing the middle of South Korea in the east-west direction. Maximum length of the cold tolerant period (the number of days between endo-dormancy release and forced dormancy release) showed the same spatial pattern. When we divide the 83 years into 3 periods (I: 1921-1950, II: 1951-1980, and III: 1981-2004) and get the average of each period, dormancy release date of period III was accelerated by as much as 15 days compared with that of period I at all locations except Jeju (located in the southernmost island with subtropical climate) where an average15-day delay was predicted. The cold- tolerant period was also shortened at 6 out of 8 locations. As a result, budburst of 'Campbell Early' in spring was accelerated by 6 to 10 days at most locations, while inter-annual variation in budburst dates was increased at all locations. The earlier budburst after the 1970s was due to (1) warming in winter resulting in earlier dormancy release (Incheon, Mokpo, Gangneung, and Jeonju), (2) warming in early spring accelerating regrowth after breaking dormancy (Busan and Jeju), and (3) both of them (Seoul and Daegu).

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.385-392
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• 2009

This study was conducted to reclassify Namweon series, black volcanic ash soils, in Jeju Island based on the second edition of Soil Taxonomy : A Basic System of Soil Classification for Making and Interpreting Soil Surveys. Morphological properties of typifying pedon of Namweon series were investigated and physicochemical properties were analyzed according to Soil Survey Laboratory Methods Manual. The typifying pedon of Namweon series has black (10YR 2/1) silt loam Ap horizon (0~11 cm) and black (10YR 2/1) silt loam BA horizon (11~72 cm). Bw horizon (72~100 cm) is very dark brown (10YR 2/2) silt loam. That occurs on lava plain derived from volcanic ash materials. The typifying pedon contains 5.2~6.4% oxalate extractable (Al + 1/2 Fe), over 85% phosphate retention, and lower bulk density than $0.90Mg\;m^{-3}$. Ap, BA, and Bw horizons of the pedon have andic soil properties. That can be classified as Andisol. The typifying pedon has an udic soil moisture regime and has a 1,500 kPa water retention of 15% or more on air-dried samples throughout all horizons, and can be classified as Udand. Ap and BA horizons (0~72 cm) have a color value, moist, and chroma of 2 or less, melanic index of 1.70 or less, and 6% or more organic carbon. That meets the requirements of melanic epipedon. That keys out as Melanudand. That has more than 6.0% organic carbon and the colors of mollic epipedon throughout a layer 50 cm or more thick within 60 cm of the mineral soil surface.. Thus, that keys out as Pachic Melanudand. The pedon has a fine-earth fraction that has a water content at 1,500 kPa tension of 12% or more on air-dried samples and has less than 35% (by volume) rock fragments. Thus, the substitute for particle-size class is medial. That has a sum of 8 times the Si (percnt by weight extracted by acid oxalate) plus 2 times the Fe (percnt by weight extracted by acid oxalate) of 5 or more, and 2 times the Fe is more than 8 times the Si. Thus, the mineralogy class is ferrihydritic. Namweon series can be classified as medial, ferrihydritic, thermic family of Pachic Melanudands, not as ashy, thermic family of Typic Melanudands.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.1
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• pp.20-27
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• 1983

A series of laboratory experiment was conducted to find out the chemical composition, characterization of humic substances by physical and chemical methods and reaction of Na-pyrophosphate, $Ca(OH)_2$ and rice straw with albumin on the degradation of soil organic matter in the volcanic ask soils of the Jeju Island. Results obtained were summarized as follows: 1. The contents of organic matter, available silicon, active iron and aluminum concentration in volcanic ash the soils were remarkably higher but available phosphorous was comparatively lower than the mineral soils. In volcanic ash soil, the contents of potassium, calcium and magnessium were higher in upland soil than that of forest soil. The ratios of active $Al^{{+}{+}{+}}/Fe^{{+}{+}}$, C/P and $K/Ca^+$ Mg were apparently high in volcanic ash soils while that of $SiO_2$/O.M. was high in mineral soil. 2. The carbon/nitrogen ratio in humin, humic acid content in organic matter, and carbon contents of humin in total carbon of soil organic matter were apparently higher in the volcanic ash soils than in the mineral soils, The total nitrogen and fractions of acid or alkali soluble nitrogen were remarkably high in volcanic ash soils while mineralizable nitrogen ($NH_4$-N and $NO_3$) contents were high in mineral soils. 3. The values of K600, RF and log K were also higher in volcanic ash soils than those in mineral soils, and the absorbance in the visible range were high and color was dark in the soil of which humification was progressed Extracted humic acid from volcanic ash soil was less reactive to the oxidizing chemical reagent and was persistance to the acid or alkali hydrolysises. 4. The major oxygen-containing functional groups in humic substances of volcanic ash soils were phenolic-OH alcoholic-OH and carboxyl groups while those in mineral soil were methoxyl and carbonyl groups. 5. Absorption spectra of alkaline solution of humic acid ranged from 200 nm to maxima 500 nm. Visible spectra peaks of from humic substances in the visible region were recognized at 350, 420, 450 and 480 nm. Only one single absorbance peak was observed in the visible region at 362 nm for Heugag series and two absorbance Peak were also at 360 nm and 390 nm for Yeungrag series. 6. Evolution of carbon as $Co_2$ was increased with addition of Na-pyrophosphate in Namweon and Heugag series, and "priming effects" took place on the soil organic matter decomposition by addition of rice straw with albumin in Ido series.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.2
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• pp.116-121
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• 1983

A study was conducted to evaluate the effect of $^{60}CO-{\gamma}$ irradiation on the preservation on Satauma mandarin in Cheju Island. Four varieties (S. m. early, S. m. Komezawa, S. m. Hayashi and S. m. Aoshima) were irradiated using 10,000Ci, $^{60}CO-{\gamma}$ ray with dosages of 0, 50, 100 and 150Krad. During 92 days of storage the effects of irradiation on mandarin porperties were as follows: At the end of storage period the accumulated fruit rotting percentage were S. m. Komezawa($T_2$);74.32%, S. m. early($T_1$);69.67%, S. m. Aoshima($T_4$);64.33% and S. m. Hayashi ($T_3$);61.79%. The rottings steadily increased from the early stage of storage and rapid spoilage continued after 59 days of irradiation. A high corelation existed between fruit rotting and varieties ($T_3$;Y=0.78x-15.30, $T_4$;Y=0.79x-12.29, $T_1$;Y=0.93x-9.01 and $T_2$;Y=0.79x-13.49) High dosages(100 and 150 Krad)improved fruit preservation during the mid storage stage. However 76 days after high dose irradiation there was no significant difference a rotting between irradiated fruit and the control. Irradiation decreased acidity of fruit during storage (p<0.01). The mean acidities of examined varieties were $T_1$;1.01%, $T_3$;1.01%, $T_4$;0.84% and $T_2$;0.77%. A significant differences were observed in acidity between varieties and dosages(P<0.01) With one exception in all treatments. the increase in free and total sugar content was not statestically significant. The exception was the 50 Krad treatment where the total sugar content decreased. $T_1$ and $T_4$ showed slightly higher value of than Brix $T_2$ and $T_3$, and were significantly(P<0.01) decreased by higher dosage. The ascorbic acid content in all treatments decreased with length of storage and also decreased significantly with a higher dosage.

• Food Science and Preservation
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• v.22 no.2
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• pp.241-250
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• 2015

This study investigated the sensory attributes of Satsuma mandarins to provide basic data for the establishment of a quality grade establishment of mandarins. Samples of the mandarins in different sizes (small, medium, and large) were collected via organic green house cultivation, conventional cultivation without pesticides and conventional cultivation in Jeju Island. Eight trained panels performed the triplicate measurements. From the results of the quantitative descriptive analysis, mandarin samples were selected with five types of appearances (gloss intensity, color intensity, peel width, damage degree, and peel texture), three types of odors (sour, sweet, fresh), six types of tastes (sour, sweet, bitter, fresh, tasteless, and off flavor) four types of texture (hardness, granule toughness, juicy, and tough feel), and three types of after-tastes (sour, sweet, and bitter). The results of the analysis of the quality characteristics of the samples showed that their, pH, total acidity and solids contents differed depending on the size of the samples more than their cultivation methods. The correlation coefficients between the quality properties of the mandarins showed that their, sample size was positively correlated with their peel width and toughness. Moreover, the soluble solid of sample was positively correlated with its color intensity, sweet and fresh orange flavor. However, soluble solid content of the samples was negatively coreelated with their bitter flavor, tastelessness, and off flavor. In the principal component analysis of the sensory attributes data, PC1 represented the soluble solid, gross intensity, orange color, sour and sweet odor, unique mandarin flavor (sweet and, fresh orange), etc., and PC2 (26.77%) the size, pH, sample acidity, and peel texture.