Combined effect of Cr-toxicity and temperature rise on physiological and biochemical responses of Atriplex halimus L.

An experiment was conducted to evaluate the combined effect of temperature (26 and 30 °C) and Cr toxicity (0, 100 and 1000 μM Cr) on growth, photosynthesis, water content, Cr and nutrients uptake and translocation. The role of antioxidative enzyme towards stresses tolerance was also investigated. Results showed that the maximum relative growth rate and leaf area per plant of Atriplex halimus L. were recorded at 100 μM Cr and 26 °C. However, presence of Cr reduced net photosynthetic and stomatal conductance rates. Overall, temperature rise enhanced the toxic effect of Cr by reducing growth and photosynthesis and inducing antioxidant enzymes activities. Furthermore, temperature rise increased nutrient uptake, as well as nutrient translocation to aboveground tissues; while it diminished Cr translocation. Finally, roots were the main sink for Cr accumulation in A. halimus. At 1000 μM Cr, root Cr concentrations reached 7.2 and 9.1 mg g-1 at 26 and 30 °C, respectively; while shoot Cr concentrations were 0.45 and 0.44 mg g-1 (26 and 30 °C, respectively). The high Cr-accumulation in roots suggests that A. halimus presents a great potential for phytoremediation, especially phytostabilisation of Cr contaminated soils.