• ALGAE
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• 제18권1호
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• pp.13-20
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• 2003

Two isolated Antarctic marine diatoms, Chaetoceros neogracile VanLandingham and Stellarima microtrias (Ehrenberg) Hasle and Sims were examined to show changes of growth and uptake rate of nitrate due to UV-B irradiance. Chlorophyll (chl) a concentration was regarded as the growth index of diatom. The diatoms were treated with UV-B radiation and cultured for 4 days under cool-white fluorescent light without UV-B radiation. Two levels of UV-B exposures were applies: 1 and 6 W $m^{-2}$. Durations of UV-B treatment were 20, 40 and 60 minutes under 6 W $m^{-2}$ and 1, 2, 3, 4 and 5 hrs under 1 W $m^{-2}$. The control groups were cultured at the same time without UV-B radiation. The growth rates of two diatoms decreased under 1 and 6 W $m^{-2}$ UV-B irradiances than that of control group. After 4 days, chl a concentrations of C. neogracile were increased more than 4 times from 133 μgo$l^{-1}$ to 632 μgo$l^{-1}$ in control group. However, the concentration of experimental groups under 1 W $m^{-2}$ UV-B were only increased from 139 μgo$l^{-1}$ to 421 μgo$l^{-1}$ during one hour and the chl a concentrations were decreased from 144 μgo$l^{-1}$ to 108 μgo$l^{-1}$ during five hour. Growth of diatom dramatically more decreased under 6 W $m^{-2}$ UV-B than 1 W $m^{-2}$ UV-B. The chl a concentration of experimental groups under 6 W $m^{-2}$ UV-B for one hour was only increased from 111 μgo$l^{-1}$ to 122 μgo$l^{-1}$. In the case of S. microtrias showed also similar pattern to C. neogracile by UV-B radiation. The uptake rates of nitrate by the two strains were decreased abruptly under 6 W $m^{-2}$ UV-B irradiances. When two strains were treated under 1 and 6 W $m^{-2}$ UV-B during one hour, the strains were only continued growth and uptake of nitrate under 1 W $m^{-2}$ UV-B. This experimental evidence shows that exposure to UV-B radiation especially to high irradiance of UV-B decreases diatom survival and causes lower decrease of nutrient concentrations by microalgae in Antarctic water. Furthermore, evidence suggests that microalgal communities confined to near-surface waters in Antarctica will be harmed by increased UV-B radiation, thereby altering the dynamics of Antarctic marine ecosystems.

• 한국작물학회지
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• 제50권2호
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• pp.84-90
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• 2005

The effects of UV-B radiation on the seedling growth, carbohydrate metabolism and antioxidants activities of rice (Oryza sativa L.) were investigated under environmentally controlled chamber. Supplementary UV­B radiation reduced dry matter as well as leaf area, there­fore, relative growth rates (RGR) of seedlings were decreased by up to half compared to control. Photosynthetic products such as soluble sugars and starch were rapidly and significantly reduced by within 1 day of enhanced UV-B radiation due to the inhibition and degradation of photosynthetic processes and thylakoid membrane integrity. In our study, nonstructural carbohydrate levels were proved to be a main indicator on UV-B­induced stress. The behavior of SOD, CAT, APX and POD activities was monitored in the leaves of rice seedlings subjected to UV-B radiation. Under UV-B treatments, SOD activity was initially increased, whereas CAT and POD activities were slowly and slightly increased. However, APX activity showed no presumable results with an increase of UV-B dose. In leaves of rice seedlings, supplementary UV-B radiation caused an increase in free putrescine and spermidine, however spermine remained unaltered, although 24-hrs UV-B treatment slightly increased. This result presumes that an excess UV-B dose may induce ethylene biosynthesis (senescence) rather than polyamine biosynthesis (defense).

• 한국산림과학회지
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• 제88권4호
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• pp.469-476
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• 1999

본 연구는 증가되는 UV-B 환경에 대한 양수(陽樹)와 중성수(中性樹)의 생장 및 생리적 반응을 탐구하고자 자작나무(Betula platyphylla var. japonica Hara)와 물푸레나무(Fraxinus rhynchophylla Hance)의 유묘(幼苗)를 대상으로 14주 동안 3 수준의 UV-B(ambient UV-$B_{BE}$, ambient+3.2, +$5.2\;KJ\;m^{-2}s^{-1}$) lamp가 설치된 야외포장에서 실시되었다. 자작나무와 물푸레나무 유묘의 수고생장(樹高生長), 근원경생장(根元徑生長), 엽면적(葉面積) 및 건물생산(乾物生産)은 UV-B 증가에 의하여 감소되었다. UV-B 증가에 의해 물푸레나무 유묘 잎의 기공저항(氣孔低抗)은 커졌으며, 엽록소(葉綠素), carotenoid 함량의 감소는 자작나무에서 보다 물푸레나무에서 더 뚜렷하였다. UV-B 흡수물질(吸收物質)의 현저한 증가는 나타나지 않았지만 자작나무에 비해 물푸레나무의 경우 다소 증가하는 경향이었다. 이러한 결과들은 UV-B 증가 환경에 대한 공시 두 수종의 생리적(生理的), 생화학적(生化學的) 반응이 다르다는 것을 의미한다.

• Journal of Photoscience
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• 제1권2호
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• pp.135-141
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• 1994

Elevated near-UV radiation, containing a large amount of UV-B and a small amount of UV-C, inhibited the development of leaves and tillers, the increase in biomass production, the elongation of plant height, the photosynthetic rate and the chlorophyll content in rice plants in a phytotron. Elevated UV-B radiation filtered through cellulose diacetate film or UV-31 cut filter (transmission down to 290 nm) similarly suppressed each growth component above. Near-UV radiation-caused injuries were alleviated either by elevated CO$_2$ atmosphere or by exposure to high irradiance-visible radiation. On the basis of these findings, we examined cultivar differences in the resistance to UV radiation-caused injuries among 198 rice cultivars belonging to 5 Asian rice ecotypes ( aus, aman, boro, bulu and tjeleh) from the Bengal region and Indonesia and to Japanese lowland and upland rice groups. It was shown that .various cultivars having different sensitivities to the effects of near-UV radiation were involved in the same ecotype and the same group, and that the Japanese lowland rice group and the boro ecotype were more resistant. Among Japanese lowland rice cultivars, Sasanishiki (one of the leading varieties in Japan) exhibited more resistance to near-UV radiation, while Norin 1 showed less resistance, although these two cultivars are closely related. It was thus indicated that the resistance to the inhibitory effects of near-UV radiation of rice cultivars is not simply due to the difference in the geographical situation where rice cultivars are cultivated. From the genetic analysis of resistance to the inhibitory effects of UV radiation on growth of rice using F$_2$ plants generated by reciprocally crossing Sasanishiki and Norin 1 and F$_3$ lines generated by self-fertilizing F$_2$ plants, it was evident that the resistance to the inhibitory effects of elevated near-UV radiation in these rice plants was controlled by recessive polygenes.

• Ocean and Polar Research
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• 제26권2호
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• pp.133-143
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• 2004

For the purpose of understanding the cloud scattering effect of UV radiation at King Sejong station In West Antarctica, we analyzed the data measured by UV-Biometer at surface and compared its result with solar radiation model. The parameterization of UV radiation by cloud ice crystal was applied to solar radiation model and the sensitivity of this model for the variation of ice crystal was tested. The cloud optical thickness was calculated by using this solar radiation model. It was compared the result from calculation with CERES satellite data. In solar radiation model, the UV radiation was less scattered with increase of ice crystal size in cloud and this scattering effect was more important to UV-A radiation than Erythemal UV-B radiation. But scattering effects by altitude of cloud was not serious. The calculated cloud optical thicknesses in Erythemal UV-B and UV-A region were compared with CERES satellite data and the result by UV-A was more accurate than Erythemal UV-B region.

• 한국토양비료학회지
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• 제37권1호
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• pp.25-30
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• 2004

본 연구는 벼 유묘기 자외선 처리에 의한 엽 신장과 출현양상의 변화를 알아보고자 수행하였다. 벼 유묘의 엽신장은 엽령에 따라 다르게 나타났다. 자외선 조사는 무처리와 비교할 때 58-66%의 엽 신장을 감소시켰다. 자외선 처리 또는 무처리 조건하에서의 엽 생장은 주로 주간에 이루어지는 졌다. 자외선에 의한 3엽의 생장은 무처리에 비해 1.7배정도 억제되었으나, 5엽 생장은 큰 차이가 없었다. 또한 스트레스에 의한 식물체내 지질과산화는 catalase와 peroxidase 활성저하로 인하여 증가하였다. 이상의 결과로 지속적인 자외선 노출은 엽 생장을 억제였으며 유묘기에 영향이 더 컸다.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제21권1호
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• pp.31-46
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• 1993

대기 가열율과 복사속의 연직 분포를 계산하기 위하여 two-stream/delta-Eddington 근사법을 이용한 복사전달모형이 개발되었다. 이 모형의 결과를 ICRCCM의 결과와 비교하므로써 모형의 완성도를 평가하였다. 이 모형은 정확성 뿐 아니라 경제적인 면에서도 태양복사를 계산하는데 적합한 것으로 증명되었다. 대기 꼭대기에서의 복사속과 지표에서의 복사속 간의 관계를 비교하므로써 자외선 B 영역(UV-B; 280-320nm)의 특징들이 검토되었다. 이 영역에서는 강한 오존 흡수가 있어 UV-B의 관계가 2차 함수로 나타난다. 또한, 성층권 오존 감소와 화산 폭발로 기인한 성층권 에어로졸 안개가 UV-B 복사에 미치는 영향을 다양한 태양의 천정각에서 조사했다. 태양의 천정각이 증가함에 따라 지표 UV-B도 증가하였다. 성층권 에어로졸은 후방 산란을 통해 행성 반사도를 증가시켰다. 행성 반사도는 에어로졸 효과로 인해 태양의 천정각이 증가함에 따라 증가한다. 그러나, 행성 반사도의 변화가 태양의 천정각 변화에 따라 민감하게 나타나지는 않는다. 이것은 태양의 천정각이 클 때 에어로졸의 산란 효과가 상대적으로 긴 복사 경로에서 포화되었기 때문일 것이다. 끝으로, 화산 폭발에서 비롯된 성층권 에어로졸이 지표 UV-B 복사 강도에 미치는 지역적 영향이 추정되었다. 고위도에서는 에어로졸의 광자 포획(photon trap)이나 일몰 효과로 복사 강도가 증가하는 반면 저위도에서는 감소한다. 고위도에서 에어로졸의 산란과 오존 흡수는 지표 UV-B 복사의 최대 증가는 봄 기간 중에 양 반구 모두 중위도에서 나타난다.

• 한국작물학회지
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• 제50권1호
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• pp.39-44
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• 2005

This study was conducted to examine the physiological and biochemical responses against UV-B radiation in the seedling of 15 different rice cultivars, having the different physiological sensitivities. Out of 15 rice cultivars tested, moderate and susceptible groups showed significant decreases in biomass and RGR (relative growth rate). Contents of total chlorophyll were reduced remarkedly by irradiation of UV-B. In all rice cultivars tested, the content of chlorophyll a was strongly decreased, while the contents of chlorophyll b were slightly reduced without showing clear different among three groups and 15 cultivars. Carotenoid content was largely reduced by UV-B radiation, whereas polyamine content was moderately increased. The contents of MDA (malondialdehyde) that reflect the level of lipid peroxidation of cell membranes were clearly increased by UV-B stress, showing higher content in susceptible cultivars than moderate and torelant cultivars. The physiological important parameters highly related to visible injury were leaf color, chlorophyll, carotenoid, and lipid peroxidation, whereas biomass and polyamines were not closely correlated. Based on this results, it was concluded that changes of visible injury and the contents of chlorophyll and MDA could be adequately applied and utilized as physiological indicators to UV-B radiation.

• 한국토양비료학회지
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• 제37권1호
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• pp.31-35
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• 2004

자외선 처리에 의한 세포 내 소기관의 구조적 변화를 관찰하기 위하여 수행하였다. 광학현미경을 통한 인산기를 가진 광합성산물은 자외선 처리시간의 증가와 함께 급격히 감소하였다. 주사전자현미경을 통한 엽 표면의 큐티클층은 자외선 처리 6시간 이후부터 파괴되기 시작하였다. 자외선에 의한 세포 수분압의 변화는 엽록체의 틸라코이드막을 파괴하였으며, 표피세포의 두께를 증가시켰는데 특히 1차 세포벽은 파괴되었으며 2차 세포벽은 리그닌의 합성 및 축적으로 인해 무처리에 비해 약 2배정도 두꺼워졌다.

• Journal of Photoscience
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• 제9권2호
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• pp.332-334
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• 2002

We examined the effects of supplementary ultraviolet-B (UV-B) radiation on the changes in synthesis and degradation of ribulose-I, 5-biphosphate carboxylase /oxygenase (Rubisco) and light-harvesting chlorophyll a/b binding protein of PSII (LHCII), as well as mRNA levels for small and large subunits of Rubisco (rbcS and rbcL, respectively) and LHCII (cab) with leaf age in UV-sensitive rice (Norin I) and UV-resistant rice (Sasanishiki). Both Rubisco and LHCII were actively synthesized until the leaf had fully expanded, and then decreased with leaf age. Synthesis of Rubisco, but not LHCII, was significantly suppressed by UV-B in Norin 1. The degradation of Rubisco was enhanced by UV-B around the time of the leaf maturation in the two cultivars. The levels of rbcS and rbcL were reduced by UV-B at the early leaf stages after emergence in both cultivars. The level of cab was first present at the highest level in the two cultivars, but drastically decreased due to UV-B treatment immediately after leaf emergence in Norin 1. It was proved that synthesis and degradation of Rubisco and LHCII greatly changed with leaf age: Rubisco synthesis was significantly suppressed by supplementary UV-B radiation at the transcription step during the early leaf stages. It was also suggested that the difference between the two rice cultivars in sensitivity to UV-B in the synthesis of Rubisco might be due to the specific suppression not only after transcription but also at transcription.