Hyeong-Ho Seo

Geographical Shift in Blooming Date of Kiwifruits in Jeju Island by Global Warming

A kiwifruit cultivar `Hayward` has been grown in Jeju Island where the current climate is suitable for growth and development of this crop. Prediction of the geographical shift in the phenology can help the kiwifruits growers to adapt to the local climate change in the future. Two phenology models (i.e., chill-day and DVS) were parameterized to estimate flowering date of kiwifruits `Hayward` based on the data collected from field plots and chamber experiments in the southern coastal and island locations in South Korea. Spatio-temporally independent datasets were used to evaluate performance of the two models in predicting flowering date of `Hayward`. Chill-day model showed better performance than DVS model (2.5 vs. 4.0 days in RMSE). Daily temperature data interpolated at a higher spatial resolution over Jeju Island were used to predict flowering dates of `Hayward` in 2021-2100 under the A1B scenario. According to the model calculation under the future climate condition, the flowering of kiwifruits shall accelerate and the area with poor flowering might increase due to the warmer winter induced insufficient chilling. Optimal land area for growing `Hayward` could increase for a while in the near future (2021-2030), whereas such areas could decrease to one half of the current areas by 2100. The geographic locations suitable for `Hayward` cultivation would migrate from the current coastal area to the elevated mountain area by 250 m.

Estimation of Duration of Low-temperature in Winter Season Using Minimum Air Temperature on January

The duration of low temperature in winter season is one of the important agrometeorological characteristics in crop growing fields. This study was conducted to develop a method to estimate the duration of low-temperature with monthly meteorological data. Using daily meteorological data from 61 observation sites from 1981 to 2010, we analyzed the relationships between the averages of monthly temperature minima and the durations of low-temperature ranging from -15 to , The monthly mean of the January minimum air temperature was appropriate for theestimation of the durations of lowtemperature below . We tested a simple second order equation to predict durations of low-temperature. To apply the equation to various temperature ranges, we suggested two different equations for the estimation of coefficients a and b, which are dependent on the base temperatures from -15 to . Thevalidation of the equations using other daily meteorological datasets from 1971 to 2000 showed that they were appropriate for the range from -10 to , but underestimated at .

Estimation of Soil CO 2 Efflux from an Apple Orchard

This study was conducted to quantify the soil respiratory emission (SR) in an apple orchard and to determine its relationship with key environmental factors such as air temperature, soil temperature and soil moisture content. Experiment was made over the period from 23 April 2007 to 31 March 2008 in `Fuji` apple orchard of National Institute of Horticultural and Herbal Science in Suwon, Gyeonggi-do, Korea. The SR was measured by using the automatic opening/closing chamber system based on a closed method. Diurnal variations in SR showed an increase around 0700 hours with increasing soil temperature, its peak between 1400 and 1500 hours, and then a gradual decrease thereafter. Daily variations in SR depended largely on soil and air temperatures over the year, ranging from 0.8 to 13.7 g . During the rainy spell in summer (JulyAutumn) with higher temperature and more precipitation, the SR was lower than that in the spring (MayJune) with moderate temperature. The SR showed a significant exponential relationship with soil temperature (

Factors Involved with the Incidence of Black Stain in Pear Fruits During Growing Season

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Quantitative Approach of Soil Prediction using Environment Factors in Jeju Island

Potential factors favoring black stains during fruit development in Pyrus serotina was investigated. Black stain occurred from young fruit till harvest. The color of the affected fruits in early stage was black or light reddish brown, but turned to light brown over time. Fruit bags with lower light transmission and inner bags with poor aeration stimulated the symptoms, and high water permeability of the bags increased the black stain. Much rain and/or poor light transmission and aeration within the canopies also favored the occurrence of black stain. Diminution of pathogenic fungi density by lime sulfur was more effective than the canopy spray of fungicide for the prevention of black stain.

Effect of Consecutive Application of Organic Matter on Soil Chemical Properties and Enzyme Activity in Potato Cultivation Soil

Parent material, climate, topography, biological factors, and time are considered five soil forming factors. This study was conducted to elucidate the effects of several environment factors on soil distribution using quantitative analysis method, called soil series estimation algorithm in the soils of Jeju Island. We selected environment factors including mean temperature, annual precipitation, surface geology, altitude, slope, aspect, altitude difference within 1 area, topographic wetness index, distance from the shore, distance from the mountain peak, and landuse for a quantitative analysis. We analyzed the ranges of environment factors for each soil series and calculated probabilities of possible-soil series for certain locations using estimation algorithm. The algorithm can predicted exact soil series on the soil map with correctness of 33% on ranking, 62% within ranking, 74% within ranking after estimating using randomly extracted environment factors. In predicted soil map, soil sequences of Entisols-Alfisols-Andisols on northern area and Alfisols-Ultisols-Andisols on western area can be suggested along increasing altitude. More modeling studies will be needed for the genesis process of soils in Jeju Island.

Effects of Differentiated Temperature Based on Growing Season Temperature on Growth and Physiological Response in Chinese Cabbage 'Chunkwang'

This study was carried out to evaluate effect of consecutive application of organic matter on soil chemical properties and dehydrogenase, acid phosphatase activity in non-volcanic ash soil during three cropping season. Organic matter mixture and organic fertilizer (MOF, ), food waste compost (FWC, ), and pig manure compost (PMC, 2,000, 4,000, and ) were applied for each cropping season. Soil pH values were increased after three cropping season in all treatment. In the soils of the increased application of PMC, soil pH, total-nitrogen, available phosphate, exchangeable cations (K, Ca, and Mg), and heavy metal (Zn and Cu) contents were increased. In addition, Soil dehydrogenase activity was significantly increased in proportions to PMC application rate and cropping season during potato cultivation period. The activity was two times higher in PMC () than control after the third cropping season. Soil dehydrogenase activity was in order of PMC>FWC>NPK+PMC>MOF. Acid phosphatase activity was higher in PMC () than other treatment. Soil Zn content and dehydrogenase activity showed linearly correlation, which were MOF (=0.427), FWC (=0.427) and PMC (=0.411, p