Bahri et al Greener Journal of Agricultural Sciences Vol. 4 (4), pp. 171-177, May 2014. ISSN: 2276-7770 Research Paper Manuscript Number: 031014140 DOI: http://dx.doi.org/10.15580/GJAS.2014.4.031014140 Photosynthetic Performance of Paulownia tomentosa (Thunb) Steud. Exposed to Heavy Metals Zinc and Cadmium Nada Ben Bahri1*, Yousr Zaouchi1, Bochra Laribi1,2, Salah Rezgui1, Taoufik Bettaieb1 1 National Agronomic Institute of Tunisia. 43, Av. Charles Nicolle-1082, Tunis, Tunisia. 2Higher Agronomic Institute of Chott-Mariem, BP 47, 4042- ChottMeriem- Sousse, Tunisia. *Corresponding Author’s Email: nbenbahri @ yahoo. fr, Tel: (+216) 71 28 71 10, Fax: (+216) 71 79 93 91 Abstract: The present study was carried out to assess the alteration in photosynthetic performance of Paulownia tomentosa seedlings produced in vitro and cultivated under glass house when exposed to trace metals: zinc (Zn) and cadmium (Cd). In this respect, Zn and Cd were added to the substrates of culture at various concentrations: Zn (250, 500, 750 and 1000 μM) and Cd (25, 50 and 75 μM). A non-supplemented substrate with metal salts was served as a control. The photosynthetic activity was evaluated through measurements of chlorophyll fluorescence and the photosynthetic pigments, namely chlorophyll a, chlorophyll b and total chlorophyll as well as the carotenoids. Main results showed that the initial fluorescence (F0) values were higher in plants grown on Zn added substrate compared to those grown in the presence of Cd. However, the Fv/Fm ratio which indicates the efficiency of photosystem II, ranged from 0.78 to 0.82 for all treatments. Additionally, the presence of 75μM Cd in the substrate stimulates the biosynthesis of chlorophyll pigments by increasing their proportions about approximately 196.77%, in comparison to the control. On the contrary, Zn significantly reduced the contents of these pigments by 9.45% compared to the control. Besides, when the Cd concentrations were 25, 50 and 75μM and Zn concentration was 250μM, the carotenoid contents increased up to 115.51%, 253.07%, 239.19% and 87.56% respectively, in comparison to the control, was noted. Overall, results of this study proved the ability of Paulownia tomentosa to maintain its photosystem activity even on Zn and Cd contaminated sites, despite the restrictive effect of Zn on the biosynthesis of photosynthetic pigments when its concentration exceeds 500 μM. Keywords: Paulownia tomentosa, chlorophyll fluorescence, photosynthetic pigments, carotenoids, Zinc, Cadmium. Return to Content View [Full Article – PDF] [Full Article – HTML] [Full Article – EPUB] Reference: Adriano D.C., 2001. Trace elements in the Terrestrial Environment. Springer Verlag, New York. 866p. Arnon D., 1949. Copper enzymes in isolated chloroplasts. 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