• Horticultural Science & Technology
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• v.33 no.2
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• pp.210-218
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• 2015

Melon leaves showing yellowing symptoms were analyzed using electron microscopy and RT-PCR for major cucurbit-infecting-viruses (CMV, MNSV, CGMMV, SqMV, WMV, KGMMV, PRSV and ZYMV) reported in Korea, but these viruses were not detected. As the result of further analysis by next-generation sequencing (NGS), the virus was identified as Cucurbit aphid-borne yellows virus (CABYV), and then confirmed by RT-PCR using CABYV-specific primers. When photosynthetic capacity was measured based on chlorophyll fluorescence yield (ChlFY), the leaves of the diseased plants showed $4.09{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, which was one-third of the readings observed for unaffected normal plants ($12.36{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). The root functions of plants affected by leaf yellowing symptoms (LYS) was $0.28mg{\cdot}g^{-1}$, about half that measured for the normal unaffected plants ($0.48mg{\cdot}g^{-1}$). Cytological observations revealed that there were no morphological differences in the palisade parenchyma and mesophyll spongy cells of the leaves between the diseased and the normal plants. However, the same leaf cells of the affected plants contained more starch granules compared to those of the normal, unaffected plants. We conclude that the LYS of muskmelon is not merely a physiological disorder but a viral disease caused by CABYV and spread by aphids.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.331-337
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• 2023

Physiological disorders in pear fruit are mainly caused by problems during the growing season, such as lack of calcium in the soil, poor drainage, low porosity, vigorous pruning, and excessive fruiting. In this study, soil physicochemical properties and leaf characteristics were analyzed in pear orchards in four regions of Korea where chlorosis symptoms occurred to determine the causes of chlorosis. The color of chlorotic leaves was diagnosed using the naked eye or SPAD and Hunter values. The soil of the chlorotic orchard had a significantly higher soil pH than that of the regular orchard. Although adequate soil depth was not significantly associated with chlorosis, combined with over-fertilization of the soil with lime, it could potentially impair plant iron uptake. Chlorotic leaves had significantly lower iron and calcium contents and significantly higher magnesium contents than those of regular leaves. Therefore, the intensive occurrence of chlorosis during secondary shoot development around June and July when it is hot and humid may be due to impaired iron and calcium absorption, leading to physiological disorders. To solve this problem, avoiding the over-application of lime and applying foliar fertilizers containing chelated iron is recommended.

• Horticultural Science & Technology
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• v.18 no.3
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• pp.399-403
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• 2000

Recently, abnormal leaf chlorosis has been observed in jujube trees of the major production area in Kyongbuk province. To determine possible causes for the observation, physico-chemical properties of the orchard soil and nutrient contents in the jujube trees were investigated. The chlorosis symptoms were categorized into three types based on the site of chlorosis initiation; leaf center, petiole, and intravein. Of the three, leaf center chlorosis was the most common. The symptom occurred more frequently in Ihyeon, Gyuam, and Geugrag soil series with previous history of apple orchard. In general, the soil and the tree showing leaf chlorosis had lesser nutrient contents than normal except P, Fe, and Zn. In particular, Mg contents in leaf, branchlet, and fruit of the tree were as much as 4 times lesser than those in normal tree; the soil also had 7.8 times lesser Mg contents. The results indicate that the abnormal leaf chlorosis in jujube tree may be caused by nutrient deficiency in soil and could be cured by proper fertilization.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2020.10a
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• pp.142-142
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• 2020

• Research in Plant Disease
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• v.12 no.3
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• pp.221-225
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• 2006

Cucumber mosaic virus(CMV) and Broad bean wilt virus 2(BBWV2) were isolated from Gentiana scabra plants showing typical mosaic and yellowing symptoms. When the inoculum of mosaic symptom propagated in Nicotiana benthamiana was inoculated to primary leaves of Vigna sinensis, the local lesions of different types was developed. Type one produced a small necrotic spot(SNS) of pinpoint type, while the other one showed a large necrotic spot(LNS) of halo type. LNS on primary leaves of V. sinensis was also induced by inoculum from yellowing symptom on G scabra. Single lesion from SNS induced a typical mosaic symptom on N. Benthamiana. On the other hand, LNS produced a chlorotic ring symptom on inoculated leaves and mosaic plus necrotic ringspot on upper leaves of N. benthamiana. An isolate of CMV from SNS and BBWV2 from LNS were detected by using dsRNA analysis, RT-PCR and agar gel double-diffusion test. Thus, our results should provide a tool of a simple method for discrimination from mixed infected plants by CMV and BBWV2.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.15
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• pp.115-121
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• 1974

Artificial induction of nitrogen deficiency symptoms (leaf chlorosis) with two root respiratory inhibitors(DNP and Na$_2$S) was studied and regarded to be the same characteristic to red discoloration in rice var. Tongil seedling leaves as well as adult ones. Tongil(IR 667) was shown to be more nitrogen sensitive and have more distinctive appearance of the leaf discoloration than Punggwang(a native Japonica-type varity.) Conclusions were drawn from the present data that so-called red discoloration of Tongil under the natural field conditions is brought about either by insufficient nitrogen supply in soils or certain factors which may limit at any time the root absorption of nitrogen (low temperature, toxic gases or substances, poor drainage, around roots, etc.) in soils even with ample supply of it.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.107-115
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• 2010

Removal and mineralization of dissolved uranium by bacteria in KURT (KAERI Underground Research Tunnel), Korea Atomic Energy Research Institute (KAERI) was investigated. Two different bacteria, IRB (iron-reducing bacteria) and SRB (sulfate-reducing bacteria) was used, and minerals formed by these bacteria were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Compared to uranyl ions, ferric ions were preferentially reduced by IRB, showing that there is no significant reduction and removal of uranium. However, uranium concentration considerably decreased by addition of Mn(II). Results show that a sulfide mineral such as mackinawite (FeS) is formed by SRB respiration through combination of Fe(II) and S without manganese sulfide formation. In the presence of Mn(II), however, uranium is removed effectively, suggesting that the sorption and incorporation of uranium could be affected by Mn(II) onto the sulide minerals.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.1
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• pp.66-71
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• 1980

Sesame cultivar Suweon 9 was sown at two planting time, June 19 and July 3, to study flowering and seed maturation process. Flowering began at 37-40 days after sowing at the 2-4th node and proceeded to upper node with the speed of 1.78 days (June 19 planting) and 1.56 days (July 3 planting) per node until Sept. 1. Sesame capsule reached its full size about 10 days after flowering. Number of sesame seed increased until 15 days, but seed weight gain occurred from 10 days to 35 days after flowering, that meant 25 days the actual seed filling period. The capsule flowered later than Aug. 14 remained immature. There was no more seed weight gain when average. temperature dropped below $20^{\circ}C$ (around Sept.15) and 50% of leaves had senesced. Discussion includes that sesame as an 8determinate plant may have independent source-sink relationship at each node.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.64-67
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• 1980

Field experiments were conducted to determine the optimum harvesting time and to evaluate the effect of Diquat spray in late seeded sesame, cultivar 'Suweon 9'. Sesame seed yield reached a plateau from Sept. 18 harvest when seed number was maximum. Thousand seed wt. increased to Sept. 29 harvest. As harvesting was delayed moisture content of capsule decreased and capsule dehiscence increased. Capsule dehiscence did not start until its moisture content dropped below 70%. Optimum harvesting might begin from the time which moisture content of capsule dropped below 70%, leaf senescence reached upper node, and 50% of capsules lost green. About 5% increase in seed weight after defoliation was estimated to be translocation from capsule wall. Diquat spray with 0.3% and 0.5% (v/v) solution of commercial Reglone (20%in A.I.) decreased rapidly capsule moisture content and promoted seed shattering. Dehiscence in 90% capsules was noted at seven days after Diquat spray. Diquat spray as a harvest aid could accelerate sesame desiccation up to 2 wks from normal field condition.

• Journal of Korean Society of Forest Science
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• v.88 no.3
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• pp.335-341
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• 1999

To investigate the effect of sulfate deposition un forest tree nutrition, 15 forest stands of Pinus thunbergii were selected throughout Yochon industrial complex, in which is influenced by chronic air pollution. Concentrations of sulfate sulfur, nitrogen, phosphorus, potassium, calcium, and magnesium were analysed fur current and 1-year-old needles of Pinus thunbergii tree. The results obtained were as follows ; 1. Significant higher accumulation of sulfate S, computed with that of unpolluted needles, was observed at all sites, ranging front 0.11% to 0.35% in current needles, and from 0.13% to 0.32% in 1-year-old needles. 2. Ranging from 0.60% to 1.42% in current needles, and from 0.58% to 0.88% 1-year-old needles, respectively, nitrogen concentrations were significantly lower at 7 sites for current needles, and at all sites for 1-year-old needles than at unpolluted site. 3. Phosphorus and potassium levels were significantly lower at very few sites, compared with unpolluted site. 4. Calcium concentrations were significantly lower at 8 sites and 9 sites for current and 1-year old needles than at unpolluted site, ranging from 0.123% to 0.352% and from 0.201% to 0.371% in 1-year old needles, respectively. 5. Ranking from 0.077% to 0.152% in current needles, and from 0.056% to 0.105% in 1-year-old needles, magnesium concentrations were lower at only 2 sites for current needles tut at 12 sites for 1-year-old needles. 6. There were significant declines of concentrations of calcium and magnesium in current needles as sulfate accumulation increased. For 1-year-old needles, there were significant negative correlations-hips between sulfate and nitrogen, potassium, calcium, and magnesium concentration. It is concluded that deposition of sulfuric air pollutant deteriorated nutrients status, resulting in tree decline, in Pinus thunbergii forest in Yochon industrial complex.