Photosynthetic Behaviour and Mineral Nutrition of Tamarix gallica Cultivated Under Aluminum and NaCl Combined Stress

The lack of knowledge of plant tolerance and differential response to aluminum (Al) encouraged many researchers, in the last decade, to elucidate Al toxicity and tolerance mechanisms. The current study reported the impact of Al, a toxic element with negative effects on plant growth and development, in halophytic plant Tamarix gallica. Plants were subjected to different Al concentrations (0, 200, 500 and 800 mu M) with or without NaCl (200 mM) supplementation. Growth, photosynthesis and mineral content were assessed. Al stress had a significant decrease on shoots' biomass production between 19 to 41%, and a little variation on chlorophyll content and photosynthetic efficiency (Fo, Fm, Fv fluorescence's and Fv/Fm). Furthermore, the Al-treatments did not affect significantly the content of potassium, calcium, and magnesium in different plant parts, whereas NaCl addition to the medium induced a decrease in these elements' concentrations. Our results have shown that T. gallica is able to accumulate the high levels of Al in shoots and roots, 6288 mu g.g(-1) DW and 7834 mu g.g(-1) DW respectively. It is considered as a hyperaccumulator plant of Al. In addition, Na+ contents in shoots and roots exceed 23000 mu g.g(-1) DW. Therefore, T. gallica presents a high tolerance at the same time to Al and NaCl phytotoxicity, so it is interesting to use in phytoremediation programs.