• Journal of Life Science
• /
• v.8 no.3
• /
• pp.272-278
• /
• 1998

To investigate the effects of different UV-B levels on plant growth, cucumber plants were subjected to three levels of biologically effective ultraviolet-B(UV--$B^{BE}$ radiation [daily dose : 0.03(No UV-B), 6.40(Low UV-B) and 11.30 (High UV-B) kJ $m^{-2}$, UV--$B^{BE}$] in the growth chambers for 3 weeks during the early growth period. High and low levels of UV-B irradiation drastically decreased both dry weight and leaf area, but increased specific leaf weight of cucumber. Plants subjected to UV-B resulted in 30% and 20% reduction of photosynthesis rate by high and low UV-B, respectively. However, respiration rate was not affected by the UV-B. With increasing UV-B intensity, total chlorophyll contents were decreased linearly, while the contents of flavonoid were increased linearly. These results suggest that the present levels of UV-B may affect the growth of cucumber plant compared with a UV-B-free condition. It is likely that the growth of cucumber will be affected by enhanced UV-B due to ozone depletion in the near future.

• Journal of Life Science
• /
• v.16 no.3 s.76
• /
• pp.522-526
• /
• 2006

To investigate the effects of UV-B on fatty acid composition, lipid peroxidation and biochemical defense responses of plant, kidney bean (Phaseolus vulgaris L.) was subjected to enhanced UV-B irradiation [daily dose : 0.02.(No UV-B) and 11.36 (enhanced UV-B) $kJ\;m^{-2};UV-B_{BE}$] for 3 weeks. UV-B drastically inhibited both height and dry weight of kidney bean. The content of malondialdehyde significantly increased by about 50% after 3 weeks of UV-B irradiation. The ratio of unsaturated to saturated fatty acids of kidney bean was increased by UV-B irradiation. Three major polyamines of kidney bean leaves : putrescine, spermidine and spermine, were observed. All of the polyamine contents were increased with UV-B irradiation. These results suggested that enhanced UV-B radiation caused oxidative stress on lipids and biochemical protection responses might be activated to prevent from damaging effects of oxidative stress generated by UV-B irradiation.

• Journal of Environmental Science International
• /
• v.7 no.5
• /
• pp.633-638
• /
• 1998

To determine whether the enhanced UV-B causes oxidative stress, and to test the relationship between plant growth response and biochemical defense response to UV-B, two soybean plants, Keunolkong, a highly UV-B susceptible cultivar, and Danyeubkong, a less UV-B susceptible cultivar, were subjected to the enhanced UV-B [daily dose : 0.06 (control) and 11.32 (enhanced UV-B) kJ $m^{-2}$ ; $UV-B_{BE}$] for 3 weeks. Contents of malondialdehyde and total carotenold were increased in Keunolkong compared with Danyeubkong by UV-B. In control plants, ascorbate level of Danyeubkong was 3 times higher than that of Keunolkong. The ratio of dehydroascorbate/ascorbate was highly increased in Keunolkong by UV-B . The activities of antioxidative enzyme such as superoxide dismutase, ascorbate peroxidase, monodehydroascorbate reductase and glutathione reductase were increased in both cultivars by UV-B. This results indicate that enhanced UV-B caused oxidative stress in both two cultivars, especially in Keunolkong. Susceptibility of two soybean cultivars to UV-B is closely related to the levels of antioxidants such as carotenoid and ascorbate.

• Korean Journal of Weed Science
• /
• v.30 no.2
• /
• pp.135-142
• /
• 2010

To investigate the effects of ultraviolet(UV-B) on growth and biochemical defense responses of plant, garden balsam (Impatiens balsamina L.) was subjected to enhanced UV-B irradiation [daily dose: 0.02 (No UV-B) and 11.34 (enhanced UV-B) kJ $m^{-2}$ ; $UV-B_{BE}$] for 3 weeks. Enhanced UV-B drastically inhibited leaf area as well as dry weight of garden balsam. The content of malondialdehyde was significantly increased by about 50% after 3 weeks of UV-B irradiation. The ratios of dehydroascorbate/ascorbate and oxidized glutathione/reduced glutathione were also considerably increased by UV-B irradiation. Three major polyamines of garden balsam leaves: putrescine, spermidine and spermine were observed. All polyamine contents were increased with UV-B irradiation. The enzyme (superoxide dismutase, ascorbate peroxidase etc.) activities of garden balsam were increased by the UV-B enhancement. Based on the results, enhanced UV-B caused oxidative stress in garden balsam and biochemical protection responses might be activated to prevent from damaging effects of oxidative stress generated by UV-B irradiation.

• Journal of Environmental Science International
• /
• v.5 no.5
• /
• pp.635-642
• /
• 1996

Rice plants, cv. Koshihikari, were subjected to the biologically effective ultraviolet-B(UV-BBE) radiation {daily dose : 0.0 (control) and 11.5 (enhanced UV-B) KJ m-2} to investigate the effect of enhanced UV-B radiation on lipid peroxidation and to determine whether carotenoids and polyamines are involved in protection mechanism against enhanced UV-B radiation. Enhanced UV-B radiation significantly depressed plant dW weight. Malondialdehyde (MDA) content in rice leaves was increased by about 30% after 6 days of UV-B irradiation. Total carotenoid contents tended to slightly decrease with the UV-B irradiation, even though there was no significance. In rice leaves, 3 major polyamines, putrescine, spermidine and spermine are observed. All of the polyamine contents were increased with UV-B irradiation. The results suggest that enhanced UV- B radiation caused oxidative stress on lipids and that polyamines may serve as a biochemiral protectant against increased UV-B radiation in rice plants.

• Journal of Korea Foresty Energy
• /
• v.19 no.1
• /
• pp.1-6
• /
• 2000

This study was carried out to investigate the growth responses of Pinus densiflora seedlings to enhanced UV-B environment for 16 weeks in the field condition. The seedlings were treated with one of three levels of UV-B dosages - ambient UV-B, ambient + 3.2, and ambient + 5.2 KJ m$^{-2}$day$^{-1}$ and the irradiation was performed at the stage before the germination, the fully expanded cotyledon, and the primary needles grown more than 0.8cm in length of the seedlings, respectively. Enhanced UV-B irradiation reduced the height and the root collar diameter growth, and dry mass production of the seedling, and T/R ratio was increased by the UV-B treatment. Difference in seedling growth was observed by difference in time of the UV-B treatment. Among the seedlings which were treated with ambient - 3.2 KJ m$^{-2}$day$^{-1}$, height and root collar diameter growth was relatively high in the seedling received the UV-B treatment at the stage before the germination. The lowest dry mass production was observed in the seedlings received the UV-B at stage of cotyledon both in two levels of enhanced UV-B treatment. Chlorophyll concentration was reduced by enhanced UV-B irradiation, and chlorophyll a/b ratio was increased by the UV-B treatment.

• Journal of Environmental Science International
• /
• v.16 no.12
• /
• pp.1345-1353
• /
• 2007

The effect of salicylic acid(SA) on antioxidant system and protective mechanisms against UV-B induced oxidative stress was investigated in cucumber(Cucumis sativus L.) leaves. UV-B radiation and SA were applied separately or in combination to first leaves of cucumber seedlings, and dry matter accumulation, lipid peroxidation and activities of antioxidant enzymes were measured in both dose and time-dependant manner. UV-B exposure showed reduced levels of fresh weight and dry matter production, whereas SA treatment significantly increased them. SA noticeably recovered the UV-B induced inhibition of biomass production. UV-B stress also affected lipid peroxidation and antioxidant enzyme defense system. Malondialdehyde(MDA), a product of lipid peroxidation, was greatly increased under UV-B stress, showing a significant enhancement of a secondary metabolites, which may have antioxidative properties in cucumber leaves exposed to UV-B radiation. Combined application of UV-B and SA caused a moderate increase in lipid peroxidation. These results suggest that SA may mediate protection against oxidative stress. UV-B exposure significantly increased SOD, APX, and GR activity compared with untreated control plants. Those plants treated with 1.0 mM SA showed a similar pattern of changes in activities of antioxidant enzymes. SA-mediated induction of antioxidant enzyme activity may involve a protective accumulation of $H_2O_2$ against UV-B stress. Moreover, their activities were stimulated with a greater increase by UV-B+SA treatment. The UV-B+SA plants always presented higher values than UV-B and SA plants, considering the adverse effects of UV-B on the antioxidant cell system. ABA and JA, second messengers in signaling in response to stresses, showed similar mode of action in UV-B stress, supporting that they may be important in acquired stress tolerance. Based on these results, it can be suggested that SA may participates in the induction of protective mechanisms involved in tolerance to UV-B induced oxidative stress.

• Journal of Korean Society of Forest Science
• /
• v.87 no.4
• /
• pp.601-610
• /
• 1998

This study was carried out to investigate the possibility of supplemental UV-B application to the hardening phase of container-grown Betula platyphylla seedlings. The containerized seedlings were grown in a growth chamber for four months and then treated with UV-B(UV-$B_{BE}$ $3.2KJ\;m^{-2}\;day^{-1}$ and $5.2KJ\;m^{-2}\;day^{-1}$) radiation and water stress regime(irrigation in one week interval) for four weeks. The differences in growth and physiological responses of the seedlings before and after the treatments were analyzed. UV-B radiation and water stress reduced height growth and leaf dry mass accumulation of the seedlings. The root collar diameter growth was reduced by UV-B radiation but increased by water stress. The reduction in leaf dry weight by UV-B radiation and water stress reduced T/R ratio of the seedling. The reduction in T/R ratio was the most apparent by water stress. Chlorophyll index observed by a chlorophyll meter was the lowest in the $5.2KJ\;m^{-2}\;day^{-1}$ of UV-B radiation, and those in the $3.2KJ\;m^{-2}\;day^{-1}$ and water stress were similar. UV-B radiation and water stress reduced both water content in the seedlings and leaf water potential, and increased leaf osmatic pressure. The water content of leaves and shoots was reduced more rapidly by UV-B radiation than by water stress treatment. In conclusion, growth responses and physiological changes in water relation by supplemental UV-B radiation which was applied to the hardening phase of container-grown Betula platyphylla seedlings were similar results to the water stress treatment.

• Journal of Environmental Health Sciences
• /
• v.34 no.6
• /
• pp.439-445
• /
• 2008

The feasibility study for the application of the removal and mineralization of Rhodamine B (RhB) was performed in a batch electrochemical reactor. The electro/UV process was consisted of DSA (dimensionally stable anode) electrode and UV-C or ozone lamp. The experimental results showed that RhB removal by the ozone lamp was higher than that of the UV-C lamp. Optimum current of the electro/UV process was 1 A. The electrochemical, UV and electro/UV process could completely degrade RhB, while a prolonged treatment was necessary to reach a high level RhB mineralization. It was observed that RhB removal in electro/UV process is similar to the sum of the UV and electrolytic decolorization. However, it was found that the COD of RhB could be degraded more efficiently by the electro/UV process (90.2 %) than the sum of the two individual oxidation processes [UV (19.7%) and electrolytic process (50.8%)]. A synergetic effect was demonstrated between the UV and electrolysis.

• Journal of Bio-Environment Control
• /
• v.10 no.3
• /
• pp.197-206
• /
• 2001

The depletion of stratospheric ozone is regarded as a major environmental threat to plant growth and ecosystem. The ozone depletion has caused plants to be exposed to an increased penetration of solar ultraviolet-B (UV-B) radiation in the 280-320 nm wavelength range. Enhanced UV-B radiation may have influence on plants biological functions in many aspects including inhibition of photosynthesis, DNA damage, lipid peroxidation, changes in morphology, phenology, and biomass accumulation. To cope with the damage by UV radiation, plants have evolved to have protective mechanisms, such as photorepair, accumulation of UV-absorbing compounds, leaf thickening and activation of antioxidative enzymes. The objective of this review is to address the effects of enhanced UV-B on plant growth, UV-B action mechanisms and protection and protection mechanisms in plants.