• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.361-361
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• 2017

The NPK are known as macro elements that affect crop growth and yield. In 1989, Cambodia Agricultural Research and Development Institute (CARDI) gave a recommendation rate of fertilizer on rice production based on soil types. This recommended rate of NPK seems however relatively low as compared to farmers' practices nowadays and the amount in the neighboring countries. The CARDI recommended rate for Prateah Lang soil type is 50kg N, $25kg\;P_2O_5$, $25kg\;K_2O\;ha^{-1}$ while recent farmers' practice rates are 55 - 64kg N, 24 - 46kg $P_2O_5$, $30kg\;K_2O\;ha^{-1}$. However, the overuse of chemical fertilizer will lead to un-preferable plant growth, insect pest, disease and economic yield. Thus, we examined the effect of different NPK application rates on the growth and yield components in Prateah Lang soil type in Takeo province to investigate appropriate rates for improving rice productivity with economic efficiency. This study was conducted from July to November during wet season in 2013. A multi-locational trial with 6 treatments (T0 - T5) of NPK rates in 5 locations (trial 1 - 5) with 3 replications was conducted. The different combinations of NPK application were employed from 0, 50, 60, 80, 100, $120kg\;N\;ha^{-1}$, 0, 25, 30 45, $60kg\;P_2O_5\;ha^{-1}$ and 0, 15, 25, 30, $45kg\;K_2O\;ha^{-1}$. Urea, DAP and KCl were used for fertilization. Split application was employed [basal: 20% of N, 100% of P and K, top dressing-1st: 40% of N (30DAT), 2nd: 40% of N (PI stage)]. Three-week-old seedlings of var. Phka Rumdoul were transplanted with 2 - 3 seedlings $hill^{-1}$ with $20cm{\times}20cm$ spacing. Plant length, tiller number at the maximum tillering stage and yield components were measured. The different rates of NPK application affected some yield components. The panicle number per hill was the most important key component followed by the spikelet number per panicle. However, the other parameters such as the filled grain percentage and 1000 grains weight had small effect or weak relation with the yield. Although the panicle number per hill had a significantly positive correlation with the stem number per hill, it was not correlated with the percentage of productive culms. The variation in the grain yield among the 5 trials was small and the difference was not significant. Although the yield tended to be higher at higher N and P application, there was no significant difference above 60kg N and $30kg\;P_2O_5$. The yield was the highest at 15, 30 and $45kg\;K_2O$ followed by $25kg\;K_2O$. The relationships between N, P and the stem number per hill were significantly linear positive, though it was not linear between K and the stem number. From these results, to increase rice productivity in the target area, farmers' effort to increase N and P input rather than CARDI recommendation up to 60kg N and $30kg\;P_2O_5$ will be sufficient considering economic efficiency. Besides, the amount of K application should be reconsidered.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.363-363
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• 2017

The NPK are known as macro elements that affect crop growth and yield. In 1989, Cambodia Agricultural Research and Development Institute (CARDI) gave a recommendation rate of fertilizer on rice production based on soil types. This recommended rate of NPK seems however relatively low as compared to farmers' practices nowadays and the amount in the neighboring countries. The CARDI recommended rate for Prateah Lang soil type is 50kg N, 25kg P2O5, 25kg K2O ha-1 while recent farmers' practice rates are 55 - 64kg N, 24 - 46kg P2O5, 30kg K2O ha-1. However, the overuse of chemical fertilizer will lead to un-preferable plant growth, insect pest, disease and economic yield. Thus, we examined the effect of different NPK application rates on the growth and yield components in Prateah Lang soil type in Takeo province to investigate appropriate rates for improving rice productivity with economic efficiency. This study was conducted from July to November during wet season in 2013. A multi-locational trial with 6 treatments (T0 - T5) of NPK rates in 5 locations (trial 1 - 5) with 3 replications was conducted. The different combinations of NPK application were employed from 0, 50, 60, 80, 100, 120kg N ha-1, 0, 25, 30 45, 60kg P2O5 ha-1 and 0, 15, 25, 30, 45kg K2O ha-1. Urea, DAP and KCl were used for fertilization. Split application was employed [basal: 20% of N, 100% of P and K, top dressing-1st: 40% of N (30DAT), 2nd: 40% of N (PI stage)]. Three-week-old seedlings of var. Phka Rumdoul were transplanted with 2 - 3 seedlings hill-1 with $20cm{\times}20cm$ spacing. Plant length, tiller number at the maximum tillering stage and yield components were measured. The different rates of NPK application affected some yield components. The panicle number per hill was the most important key component followed by the spikelet number per panicle. However, the other parameters such as the filled grain percentage and 1000 grains weight had small effect or weak relation with the yield. Although the panicle number per hill had a significantly positive correlation with the stem number per hill, it was not correlated with the percentage of productive culms. The variation in the grain yield among the 5 trials was small and the difference was not significant. Although the yield tended to be higher at higher N and P application, there was no significant difference above 60kg N and 30kg P2O5. The yield was the highest at 15, 30 and 45kg K2O followed by 25kg K2O. The relationships between N, P and the stem number per hill were significantly linear positive, though it was not linear between K and the stem number. From these results, to increase rice productivity in the target area, farmers' effort to increase N and P input rather than CARDI recommendation up to 60kg N and 30kg P2O5 will be sufficient considering economic efficiency. Besides, the amount of K application should be reconsidered.

• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.421-426
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• 2015

The objective of this paper is to look into the growth of Cryptomeria japonica stand in South Korea along with the evaluation on their yields, followed by their carbon stocks and removals. A total of 106 sample plots were selected from Jeonnam, Gyeongnam, and Jeju, where the groups of standard are grown. We only used 92 plots data except outlier. As part of the analysis, the Weibull diameter distribution was applied. In order to estimate the diameter distribution, the growth estimation equation for each of the growth factors including the height, the diameter at breast height, and the basal area was drafted out and the verification for each equation was examined. The site index for figuring out the forest productivity of Cryptomeria japonica stand for each district was also developed as a Schumacher model and 30yr was used as a reference age for the estimation of the site index. It was found that the site index for Cryptomeria japonica stand in South Korea ranges from 10 to 16 and this result was used as a standard for developing the stand yield table. According to the site 14 in the stand yield table, the mean annual increment (MAI) of the Cryptomeria japonica reaches $7.6m^3/ha$ on its 25yr and its growing stock is estimated to be at $190.1m^3/ha$. This volume is about $20m^3$ as high as that of the Chamaesyparis obtusa. Furthermore, the annual carbon absorptions for a Cryptomeria japonica stand reached the peak at 25yr, which is 2.14 tC/ha/yr, $7.83tCO_2/ha/yr$. When compared to the other conifers, this rate is slightly higher than that of a Chamaecyparis obtusa ($7.5tCO_2/ha/yr$) but lower than that of the Pinus koraiensis ($10.4tCO_2/ha/yr$) and Larix kaempferi ($11.2tCO_2/ha/yr$). With such research result as a base, it is necessary to come up with the ways to enhance the utilization of Cryptomeria japonica as timbers, besides making use of their growth data.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.1
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• pp.68-76
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• 1996

To elucidate the optimum fertilizer level and application method for band application under puddled-soil drill seeding in Jeonbuk series of fluvio-marine alluvial soil at National Honam Agricultural Experiment Station in 1995, using Dongjinbyeo, slow releasing compound fertilizer of 100％ and 80％ to conventional application level was applied totally as basal fertilizer simultaneously with seeding under 3cm and 5cm depth from soil surface in a distance of 4cm from the seeded row. Plant height was taller and tiller number was higher in band application than conventional application but ratio of effective tiller was vice versa. Panicle number was more but ratio of effective tiller ratio was lower in 100％ than 80％ level of band application and they were higher in 3cm than 5cm depth from soil surface. Leaf area index and dry weight was higher in conventional application at early growth stage but was vice versa after maximum tillering stage, and they were higher in 3cm depth at early growth stage but 5cm depth after maximum tillering stage. NH$_4$-N in soil was higher in conventional application at 25 days after seeding but, thereafter was lower than band application and it was higher in 3cm than 5cm depth till 40 days after seeding but was versa, thereafter. Lodging degree was slightly higher in band application, 100％ level and 5cm depth than in their counterparts. Panicle number and grain number per $m^2$ was lower in conventional application than 80％ or 100％ level of band application without significant difference between band application levels or application methods. Yield was higher at 80％ level of band application under 3cm depth than conventional application, but no significantly different among other application methods. Therefore, 80％ level of band application under 3cm depth of soil surface was more effective for puddled-soil drill seeding on the basis of the reduction of application efforts, better plant growth and higher yield in rice.

• Journal of Korean Society of Forest Science
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• v.62 no.1
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• pp.24-42
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• 1983

To develop Ilex cornuta which grow naturally in the southwest seaside district as new ornamental tree, the author chose I. cornuta growing in the four natural communities and those cultivated in Kwangju city as a sample, and investigated its ecology, morphology and characteristics. The results obtained was summarized as follows; 1) The natural distribution of I. cornuta marks $35^{\circ}$43'N and $126^{\circ}$44'E in the southwestern part of Korea and $33^{\circ}$20'N and $126^{\circ}$15'E in Jejoo island. This area has the following necessary conditions for Ilex cornuta: the annual average temperature is above $12^{\circ}C$, the coldness index below $-12.7^{\circ}C$, annual average relative humidity 75-80%, and the number of snow-covering days is 20-25 days, situated within 20km of from coastline and within, 100m above sea level and mainly at the foot of the mountain facing the southeast. 2) The vegetation in I. cornuta community can be divided that upper layer is composed of Pinus thunbergii and P. densiflora, middle layer of Eurya japonica var. montana, Ilex cornuta and Vaccinium bracteatum, and the ground vegetation is composed of Carex lanceolata and Arundinella hirta var. ciliare. The community has high species diversity which indicates it is at the stage of development. Although I. cornuta is a species of the southern type of temperate zone where coniferous tree or broad leaved, evergreen trees grow together, it occasionally grows in the subtropical zone. 3) Parent rock is gneiss or rhyolite etc., and soil is acidic (about pH 4.5-5.0) and the content of available phosphorus is low. 4) At maturity, the height growth averaged $10.48{\pm}0.23cm$ a year and the diameter growth 0.43 cm a year, and the annual ring was not clear. Mean leaf-number was 11.34. There are a significant positive correlation between twig-elongation and leaf-number. 5) One-year-old seedling grows up to 10.66 cm (max. 18.2 cm, min. 4.0 cm) in shoot-height, with its leaf number 12.1 (max. 18, min), its basal diameter 2.24 mm (max. 4.0 mm, min. 1.0 mm) and shows rhythmical growth in high temperature period. There were significant positive correlations between stalk-height and leaf-number, between stalk-height and basal-diameter, and between number and basal diameter. 6) The flowering time ranged from the end of April to the beginning of May, and the flower has tetra-merouscorella and corymb of yellowish green. It has a bisexual flower and dioecism with a sexual ratio 1:1. 7) The fruit, after fertilization, grows 0.87 cm long (0.61-1.31 cm) and 0.8 cm wide (0.62-1.05 cm) by the beginning of May. Fruits begin to turn red and continue to ripen until the end of October or the beginning of November and remain unfading until the end of following May. With the partial change in color of dark-brown at the beginning of the June fruits begin to fall, bur some remain even after three years. 8) The seed acquision ratio is 24.7% by weight, and the number of grains per fruit averages 3.9 and the seed weight per liter is 114.2 gram, while the average weight of 1,000 seeds is 24.56 grams. 9) Seeds after complete removal of sarcocarp, were buried under ground in a fixed temperature and humidity and they began to develop root in October, a year later and germinated in the next April. Under sunlight or drought, however, the dormant state may be continued.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.spc
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• pp.47-52
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• 2008

This study was carried out to improve the rice grain quality of Ilpum cultivar, especially to reduce the chalky rice rate by controlling top dressing of nitrogen application ratio at the tillering and panicle initiation stage. In the rice plant growth, the number of tiller and leaf area index of maximum tillering stage were influenced by basal dressing and top dressing at tillering stage; however those of heading stage were mainly influenced by top dressing at panicle initiation stage. In yield and yield components, they were influence by the top dressing at panicle initiation stage and the rice yield was increased by percentage of the top dressing. The protein content of rice grain was increased as the rate of top dressing at panicle initiation stage was increased. The rate of chalky and damaged rice was remarkably increased as the top dressing ratio was increased, resulting in reducing the rate of head rice rate. As the results, the characteristics of milling and rice quality was improved when the amount of top dress was reduced as 50% at the panicle initiation stage, and the yield of head rice also increased.

• Journal of Korean Society of Forest Science
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• v.105 no.3
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• pp.342-350
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• 2016

This study aims to make the stand density management diagram which is very useful for establishing systematic management plan and obtaining management goal in Pinus densiflora forest. To estimate 5 models mainly composed of stand density management diagram, we used total of 1,886 sample plots having more than 75% of the total basal area of the pine trees in each stand. To test the goodness of fit, $X^2$ was computed with a significance level of 5%, and the acceptable error range as 20%. Also standard deviation of the model was $34.59m^3{\cdot}ha^{-1}$, minimum acceptable error range was 16.59% and coefficient of variation was 22.11%. If we use the stand density management diagram, it would be useful to establish the timber yield and thinning plan understanding the pathway of stand density management.

• The Korean Journal of Mycology
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• v.27 no.4 s.91
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• pp.280-282
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• 1999

A new disease on mask melon grown under plastic film houses was found in Namhae area in May of 1999. Gray to dark brown mold were grown on the surface of matured fruits and infected inside tissues were discolored and rotten. Basal part of the fruit and blossom-end were frequently infected and colonized by fungi. About 2.2% of matured fruits were infected in the surveyed plastic film houses. The causal organism was isolated from the lesion and identified as Botrytis cinerea. The conidia in mass were hyaline or gray, 1-celled, mostly ellipsoid or ovoid and sized $8.8{\sim}21.2{\times}6.5{\sim}13.1\;{\mu}m$. Hyaline or pigmented conidiophores were tall, slender and determinated and, sometimes branched irregularly in upper part. Enlarged or rounded apical cells bear conidial cluster and sized $18.4{\sim}81.1{\times}4.3{\sim}11.4\;{\mu}m$. Optimum temperature for mycelial growth was recorded at $15{\sim}25^{\circ}C$. This is the first report on gray mold of melon caused by Botrytis cineria in Korea.

• Korean Journal of Plant Tissue Culture
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• v.26 no.2
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• pp.115-119
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• 1999

The single node cuttings of sweet potato (cv. Mokpo #29) plantlets maintained in vitro were cultured with (MF+) or without membrane filter (MF-) under photomixotrophic (PM), hetrotrophic (HT) and autotrophic (AT) conditions. Shoot length was the greatest (11.9cm) in 3$0^{\circ}C$ (HT) treatment and it was the shortest (3.4 cm) in $25^{\circ}C$ (PM) treatment. Nodal explants cultured in 3$0^{\circ}C$ treatment looked more vigorous than those of $25^{\circ}C$ in appearance, and node number was the greatest (10.5 per plantlet) among the treatments. But plantlets grew in 3$0^{\circ}C$ (HT) treatment were observed all overgrown. The size in leaf area was about 2 times greater and shoot length was about 2 times shorter in PM than in HT condition. Percent dry matter of shoots was 5.9% (HT) and 7.4% (PM) in $25^{\circ}C$ treatment and 6.1% (HT) and 7.4% (PM) in 3$0^{\circ}C$ treatment. Plantlets cultured in the MF+ treatments were less succulent than those cultured in the MF- treatment. Vitrified plantlets were examinated 14.8% (both $25^{\circ}C$ and 3$0^{\circ}C$) in PM condition and 22.2% ($25^{\circ}C$) and 31.5% (3$0^{\circ}C$) in HT condition. Sucrose was necessary for the survival of in vitro plantlets. In the sucrose-free medium, explants cultured in the MF- had turned yellow and were dead after 30 days of culture. But explants cultured in the MF+ were alive and produced plantlets with shoot and root (AT). On the other hand, the survival of explants on the MS basal medium (sucrose-free and hormone-free) depended entirely upon the MF attachment.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.23-29
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• 2014

Open- to closed canopy stage and it's ecological characteristics in vegetation succession are commonly described, but poorly understood in Korea. Vegetation development on structure, environment and understory abundance were studied for 16 yr in post-clearcut Pinus densiflora forests in the southern Gangwon-do province by applying space-for-time approach. We sampled 210 plots (10 for structure and 200 for understory) for four seral stages (1yr, 3yr, 10yr and 16yr). After clear-cut, mean stem density increased gradually to $5,714{\pm}645$ stems/ha after 16 years and mean basal area was also from $5.5{\pm}0.7m^2/ha$ after 10 years and doubled at $10.0{\pm}1.6m^2/ha$ in 16 years. Woody debris and bared soil on the forest floor peaked at 11--- after 10 years and at 10.3--- after 3 years, respectively. In understory mean cover declined with all growth form groups following succession, but in richness, forb specie increased with structural development during 16 years. Our study suggested that overstory development did not suppressed whole understory properties especially in richness, thus appeared to act as a filter selectively constraining the understory characteristics. However only long-term studies are essential for elucidating patterns and processes that cannot be inferred form short-term or space-for-time researches. Strong negative relationship between overstory and understory characteristics in conventional models surely reexamined.