• Korean Journal of Environmental Agriculture
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• v.17 no.2
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• pp.174-181
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• 1998

In four citrus grow of Satsuma mandarin (rootstock of trifoliate orange) including two grove of organical management and two groves of conventional management, spores of arbuscular mycorrhizal(AM) fungi were identified and seasonal changes in spore density in soils and AM colonization of citrus roots were investigated. AM colonization in weeds found in the groves were also examined. Three species of Glomus (G.deserticola, G. vesiculiferum, G. rubiforme ) and one unknown species of Acaulospora were observed in all of the groves. Annual mean density of AM fungal spores were in the range of 10,000${\sim}$40,000 per 100g soil with more spores in the organically-managed groves. The least spores were observed in December in all groves, and the most spores in April in the organically-managed groves while in February or April in the conventionally- managed. Annual mean AM colonization more 27% of citrus root were observed in the organically-managed with the high peaks in April and October and the minimum in August, while mean colonization less than 15% in the conventionally-managed with the peak in February and the minimum in different times depending on groves and years. AM colonization corresponded to a sigmoidal curve consisting of a laf phase during winter and a subsequent increase in spring, then succeeded by a maximum, and then a decrease at the end of vegetation. Fungal spore density and AM colonization showed a parallel pattern during the sample period. The seasonality appeared to be related more to the phenology of the plant than to the soil factors. Generally more spore density and AM colonization were found in organically managed groves. AM colonization was not correlated with available P and organic matter content in soil in this field investigation. Among sixteen weed species found in the groves, Astrogalus sinicus of Leguminosae, Portulaca oleracea of Portulacaceae showed high colonization in all groves and they can be considered as a source of inoculumn and host plants for propagation of AM fungi.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.542-549
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• 2021

Citrus leafminer (Phyllocnistis citrella) is an economically important pest in citrus orchards. This study was conducted to elucidate the over-wintering stage of P. citrella through experiments on the survival rate of P. citrella at low temperatures and field investigations during the winter season. There was a significant difference in the survival period depending upon the over-wintering stage of P. citrella at low temperatures, and the adults survived longer than the pupae. Evaluation of the survival period after inoculating citrus orchards with P. citrella adults and pupae showed that only the adults survived until mid-March of the following year, but all pupae died in January. This suggests that considering the fact that the germination of spring shoots in Jeju generally begins in mid-March, over-wintering adults are likely to form an early population the next year. However, pupae may not contribute to the formation of the initial population in the early season after wintering in fall shoots that are prone to freezing damage in winter because P. citrella could only survive in pupal chambers formed in fall shoots. Therefore, these results suggest that P. citrella adults that emerge in late autumn can over-winter in citrus orchards in Jeju, Korea.

• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.181-186
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• 1997

Since volcanic ash soils in Cheju island have high capacities of adsorption and immobilization of phosphate, a relatively high rate of P application has been recommended in citrus orchards for many years and such a large amount of P application could be problematic both in agricultural and environmental point of view. The objective of this study was to test whether arbuscular-mycorrhizae can be used to improve P availability in Cheju citrus orchard soils. Soil, root and leaf samples were taken from 14 citrus orchards of different location and soil texture. Mycorrhizal spore distribution in the soils, mycorrhizal infection ratio on the citrus roots, and mineral nutrients in leaf samples were determined. Numbers of mycorrhizal spore were in the range of $9,000{\sim}40,000/100g$ soil. The population level was not correlated with any of the soil characteristics examined. Mycorrhizae were found in all of the examined orchards and root infection ratio varied between $14{\sim}60%$. The mycorrhizae infection ratio differed substantially in different soils. Although root infection was high at soils with low extractable P level, it was not significantly correlated with other soil factors measured. Since a positive correlation was observed between leaf P concentration and root infection, enhancement of P uptake seemed to be associated with mycorrhizal infection. These results indicate that mycorrhizae could be a useful method to reduce P applications in Cheju citrus orchards.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.161-166
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• 1984

The Cheju citrus orchards have been chemically fertilized with both phosphates high in Ca and Mg contents and potassium. The amount of chemical fertilizers consumed per unit area of cultivated land and the ratios of $P_2O_5$ and $K_2O$ to N in chemical fertilizers applied were much higher in the Cheju Island than those of the Korean mainland. These trends were particularly prominant in Southern Cheju where 70% of the Cheju citrus orchards are located. As the result of heavy applications of phosphate fertilizers, the available phosphorus of citrus orchard soils increased with increasing number of years under cultivation. The available phosphorus of sub-soil increased slightly with the number of years under cultivation compared to that of surface soil. Base saturation and pH increased with the number of years under cultivation, inasmuch as exchangeable bases such as Ca, Mg and K increased predominantly, but the cation exchange capacity did not vary in the citrus orchard soils.

• Korean journal of applied entomology
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• v.55 no.4
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• pp.483-487
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• 2016

The damage of citrus fruits caused by Scirtothrips dorsalis Hood has being increased in Jeju, Korea. The seasonal abundance of S. dorsalis and its injury symptoms in citrus orchards have been studied since the endemic outbreak in Jeju, but studies for the occurrence pattern of S. dorsalis in citrus orchards influenced by adjacent primary hosts have not been fully conducted yet. We selected kiwi- and mango-citrus adjacent orchards to study the migration pattern of S. dorsalis toward to citrus orchards. Yellow-colored sticky traps were used for monitoring the seasonal abundance of S. dorsalis and their migration pattern in two orchards. In citrus orchards, also, we placed sticky traps at 0, 5, 10, 15 and 20 m apart from the border of kiwi orchard, and 0, 7 and 20 m apart from the border of mango orchard. The seasonal occurrence pattern of S. dorsalis caught on sticky traps were similar between two adjacent orchards. However, the abundances in kiwi or mango orchard was much higher than those of citrus. Also, it was found that densities, distribution and damage of S. dorsalis in citrus orchards depend highly on the distance from the border of kiwi and mango orchards. This result suggested that the primary hosts such as kiwi and mango plants influence the occurrence of S. dorsalis in adjacent citrus orchards. And this information may provide a basic direction for establishing the management strategy of S. dorsalis in citrus orchards.

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.148-151
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• 2011

본 연구의 목적은 농촌진흥청 국립원예특작과학원 감귤시험장에서 개발된 감귤 다공질 필름 멀칭재배법의 기술가치를 평가하는 것이다. 이는 농업 R&D사업의 효율성과 실용성 제고를 위하여 이용될 수 있을 것이다. 분석결과에 따르면, 감귤다공질 필름 멀칭 재배법 개발에 따른 기술가치평가액은 할인율 수준에 따라 최소 421.64억 원(할인율 10%)에서 최대 550.18억 원(할인율 6%), 평균 480.34억 원(할인율 8%)으로 추정되고, 내부수익율 IRR의 값은 가정했던 할인율(6%~10%)보다 훨씬 크고, 순현재가치(NPV)는 영보다 훨씬 크며, B/C 비율도 20 이상으로 나타나 감귤 다공질 필름 멀칭 재배법 개발사업의 경제적 타당성은 있는 것으로 판단된다.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.568-571
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• 2010

본 연구의 목적은 감귤 기능성물질의 산업화 타당성 분석을 하는 것이다. 구체적인 경제성 분석방법은 순현가와 투자수익률(내부수익률)을 이용한 기본적인 경제성분석과 손익분기점분석, 그리고 주요변수들의 변화에 따른 순현가의 변화를 파악하기위한 민감도분석이고, 정책적 분석은 감귤기능성 물질산업화가 감귤산업 전체에 미치는 파급효과를 계량적, 정성적으로 분석하였다. 감귤 기능성물질의 산업화 타당성 분석결과에 따르면, 미숙과 감귤 2만톤과, 감귤박 2만톤을 처리한다고 가정했을 경우 감귤산업에 미치는 경제적 효과는 연간 5백억원으로 나타났다. 이러한 막대한 경제적 효과는 본 사업에 투자되는 전체비용 약 1백억원, 10년 사업기간을 가정하면 연간 10억원의 설비투자비로 그의 50배의 경제적 파급효과를 나타날 수 있기 때문에 감귤기능성물질의 산업화효과는 매우 큰 것으로 나타났다.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.781-784
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• 2011

본 연구의 목적은 농촌진흥청 국립원예특작과학원 감귤시험장에서 개발된 감귤신품종인 하례조생의 개발의 기술가치를 평가하는 것이다. 이는 농업 R&D사업의 효율성과 실용성 제고를 위하여 이용될 수 있을 것이다. 분석결과에 따르면, 감귤신품종 개발에 따른 기술가치평가액은 할인율 수준에 따라 최소 638.7억 원 (할인율 10%)에서 최대 1,088.7억 원(할인율 6%), 평균 829.17억 원(할인율 8%)으로 추정되고, 내부수익율 IRR의 값은 가정했던 할인율(6%~10%)보다 훨씬 크고, 순현재가치(NPV)는 영보다 훨씬 크며, B/C 비율도 60 이상으로 나타나 신품종개발사업의 경제적 타당성은 있는 것으로 판단된다.

• Applied Biological Chemistry
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• v.23 no.3
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• pp.184-188
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• 1980

A survey of pesticide and copper residues of the citrus orchard soil was conducted during October 1979-June 1980 in Jeju, Seogwipo county. The citrus orchards were classified into five groups according to different cultivated period; 5 year orchard, 10 year orchard, 15 year orchard, 20 year orchard, and 30 year orchard. Each of the above samples was divided again to three layers of soil depth; the surface layer$(0{\sim}10cm)$, the middle layer $(10{\sim}20cm)$, and the bottom layer $(20{\sim}40cm)$. In this experiments, Kelthane and Akar, as well as copper residues were detected in all soil samples. Residue levels of above chemicals were increased in soils of orchard with longer cultivation periods, and at the same time, decreased with soil depth. The residues of those ranged as follows; a) from trace to 1.359ppm in Kelthane, b) from trace to 0.925ppm in Akar, and c) from trace to 40.734ppm in copper. It is noted that the average residues of Kelthane was 0.251ppm, Akar, 0.120ppm, and that of copper was 2.168ppm, respectively.

• 농업기술회보
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• v.48 no.4
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• pp.42-42
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• 2011

감귤재배 시 반드시 필요로 하는 양분 중의 하나인 붕소는 잎에서 광합성 작용으로 만들어진 당분을 과실, 뿌리 및 줄기 등으로 이동하도록 돕는다. 하지만 적은 양으로 민감하게 피해현상이 발생하므로 일반 온주밀감재배에는 붕소를 별도로 거의 시용하지 않았다. 그러나 최근 신품종이 보급되면서 특이 품종에서 붕소의 결핍증상이 쉽게 나타나고 있어 이에 대한 사례와 결핍 시 방지대책과 과잉으로 사용 시 나타나는 피해증상을 조사했다.