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Document Type |
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Article In Journal |
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Document Title |
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Effects of Enhanced UV-B Radiation and Drought Stress on Photosynthetic Performance of Lettuce (Lactuca sativa L. Romaine) Plants تأثيرات الاشعة فوق البنفسجية وإجهاد الجفاف على التمثيل الضوئى لنبات الخس |
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Subject |
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Enviromental sciences |
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Document Language |
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English |
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Abstract |
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Aims: The aim of the present study was to investigate some biochemical changes in field
grown lettuce (Lactuca sativa L. cv Romaine) plants in terms of importance of the
accumulation of anthocyanins, flavonoids and photosynthetic pigments as well as
photosynthetic limitations which changed during exposure of plants to drought stress and
UV-B radiation in order to circumvent the deleterious effects of these Stresses.
Place and Duration of Study: The experiment was conducted under filed conditions from
November 2012 to January 2013, at the Agricultural Research Center, KAU.
Methodology: The experimental design was a factorial arrangement in randomized
complete blocks with four replicates. The first factor was UV-B (300 nm). The second factor
was irrigation regime (complete irrigation to field capacity and limited irrigation. Gas
exchange measurements were carried out using a LI-6200 portable IRGA. Chlorophyll
fluorescence of Fv/Fm was measured by PAM 2000 fluorometer. Biochemical analyses and
antioxidant enzymes assays were performed according to the appropriate methods.
Results: Exposure of lettuce plants to enhanced UV-B radiation and drought stresses (DS)
negatively and significantly affected the process of photosynthesis including CO2
assimilation (PN), stomatal conductance to water vapour (gs) and transpiration rate (E).
However, the amplitude of the effects of both stressors was dependent on the interactions.
This resulted in alleviation of the negative effect of drought on photosynthesis and
transpiration by UV-B radiation as the water stress intensified. Intercellular CO2 (Ci)
concentration was only reduced due to water stress compared to control plants. The
maximum efficiency of photosystem II (Fv/Fm) was not affected by UV-B radiation stress but
reduced by drought. There was an increase in the activities of some antioxidant due to both
stresses when applied singly and in combination UV-B irradiation increased the contents of
the UV-B absorbing compounds (carotenoids, soluble phenols, anthocyanins), while
drought stress caused a notable increase in free proline content. Increase in content of
Proline may be the drought-induced factor which plays a protective role in response to
UV-B.
Conclusion: UV-B radiation provoked in general more severe damage, evaluated as
changes in the amounts of stress markers, than DS, when applied separately. Under
multiple stress conditions, each of the stress factors seems to bring out some adaptive
effects to reduce the damage experienced by plants caused by the other one. DS can
induce accumulation of UV-B absorbing compounds (flavonoids, carotenoids and soluble
phenols), which is likely to offer some increased protection from UV-B. |
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ISSN |
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2347-565X |
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Journal Name |
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Annual Research & Review in Biology |
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Volume |
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4 |
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Issue Number |
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11 |
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Publishing Year |
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1435 AH
2014 AD |
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Article Type |
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Article |
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Added Date |
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Tuesday, April 1, 2014 |
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Researchers
| جلال محمد باصهي | Basahi, Jalal M. | Researcher | | |
| اقبال محمد اسماعيل | Ismail, Iqbal M. | Researcher | | |
| ابراهيم عبدالمجيد حسن | Hassan, Ibrahim A. | Researcher | | ihassan_eg@yahoo.com |
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Files
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36749.pdf
| pdf | Effects of Enhanced UV-B Radiation and
Drought Stress on Photosynthetic Performance
of Lettuce (Lactuca sativa L. Romaine) Plants |
|