Physiological response of metal tolerance and detoxification in castor (Ricinus communis L.) under fly ash-amended soil

Abstract

Castor ( Ricinus communis L.) is a metal tolerant plants and its ability to survive in highly polluted sites as well as its capacity for metal accumulation. There are very few reports on their physiological mechanism of metal tolerance and detoxification under fly ash. Therefore, an in-situ experiment was designed to study its biomass accumulation, photosynthetic response and antioxidative metabolism under different levels of fly ash amendments. Significant (P < 0.05) increase in plant biomass and metal tolerance index was observed in R. communis under 50 % fly ash in soil amendments in comparison to the control plants. In addition, photosynthetic activity was not significantly altered under fly ash amended soil in comparison to the garden soil, but these responses/activities were remarkable lowered under bare fly ash. The induction of antioxidant enzymes was also observed in different tissue over control under fly ash treatments. The bioconcentration factor (BCF) of Al, Fe, Zn, Mn, Cu and Cr in R. communis were recorded greater than one under fly ash (50%) with soil amendments. Therefore, it concluded that it can be used for phytoremediation of fly ash and fly ash (50%) with soil amendments enhanced phytoremediation ability.

The Phytoremediation Potential and Physiological Adaptive Response of Tamarix tetrandra Pall. Ex M. Bieb. during the Restoration of Chronosequence Fly Ash Deposits

“…Additionally, in the leaves of T. tetrandra at L2, a lower content of Chl a, Chl b and Tot Carot was found than at L1 and the Control site, which is in accordance with the lower values of Fv/Fm measured at that site, and in our study, it was expressed through a positive correlation between Fv/Fm and Chl a, Chl b and Tot Carot (r = 0.964, r = 0.960, r = 0.922, respectively). Similar results revealing a decrease in photosynthetic efficiency and concentrations of phytosynthetic pigments Chl a, Chl b, Chl a + b and Tot Carot have been observed in many plant species growing on FA in comparison to soil— Ricinus communis [ 10 ], Dactylis glomerata [ 11 ], Withania somnifera [ 14 ], Festuca rubra and Calamagrostis epigejos [ 25 ], Miscanthus x giganteus [ 38 ], Tamarix sp., Spiraea x vanhouttei, Populus alba , Rocinia pseudoacacia , Amorpha fruticosa [ 7 , 21 , 24 ], Cicer arietinum [ 27 ], Prosopis juliflora L. [ 31 ], Beta vulgaris [ 68 ] and Cassia surattensis [ 69 ]. The negative correlation between B and Se concentrations in tamarisk leaves and the parameters Fv/Fm, Chl a, Chl b and Tot Carot ( Table 5 ) indicates that an increase in the concentration of these chemical elements significantly reduced photosynthetic efficiency and phytosynthetic pigments ( p < 0.001), especially at L2, where concentrations of both elements were in the toxic range [ 35 ].…”

“…The degradation observed in the carotenoids for tamarisk at L2 results in the decrease in plant resistance to ROS, favouring an increase in lipid peroxidation rates and MDA concentrations, as was found for Dactylis glomerata L., Festuca rubra L. [ 11 , 15 ] and Cassia occidentalis L. [ 16 ] too. Moreover, MDA concentrations 2 to 3 times higher were found in the leaves of R. communis [ 10 ] and Cicer arietinum L. [ 27 ] growing on soil with an ash content of 50% and 100%. In our study, the higher MDA content in tamarisk leaves at L2 when compared to L1 and the Control site is in line with the lower photosynthetic efficiency, lower concentration of Chl, Tot Carot, Ph Bound and lower radical scavenging activity of ethanolic leaf extract on the DPPH radical expressed as lower IC 50 values determined at L2 ( Table 4 ).…”

“…However, the phytorestoration process of such habitats is limited by multiple stress factors, such as the sandy texture of the ash, low moisture, low organic matter content, a deficit of the essential nutrients N, P, Mn and Zn, high temperatures and phytotoxicity due to high heavy metal(loid) and soluble salt content, which often act synergistically and cause various physiological and biochemical changes in tissue and inhibit plant growth [ 6 , 7 , 8 ]. Hence, identifying potential plant species suitable for the phytoremediation of FA dumps is an extremely challenging process that requires an understanding of their functional properties and physiological adaptive response [ 9 , 10 , 11 , 12 ].…”