Hydroponic Screening of Willows (SalixL.) for Lead Tolerance and Accumulation

Abstract

Lead tolerance and accumulation in five willow clones were investigated using a nutrient film technique. Plants were exposed to 0, 48, 121, 169, or 241 microM Pb for 14 days. Tolerance indices (TI) and critical toxicity thresholds (EC50) were determined for five willow clones. SX61 had the highest TI values (92%) in the 48 and 121 microM Pb treatments, as well as the highest EC50 threshold values (70.5 microM for roots, 155.9 microM for aboveground tissue), indications of a high degree of tolerance to Pb. This clone also developed the highest biomass of all the clones tested. We found significant variation in willows' lead accumulation. The highest Pb content in roots (24 mg plant(-1)) and aboveground tissue (7.6 mg plant(-1)) was recorded in the 48 microM Pb treatment in SX61. Based on high biomass, TI, ECso, and Pb content in plant tissues, SX61 holds promise for phytoextraction of lead.

Potential of sunflower, castor bean, common buckwheat and vetiver as lead phytoaccumulators

“…Considering the low Pb concentrations in the solution, there was different growth of the species in response to the applied doses (Figure 1), confirming the fact that plant species respond differently to the exposure to Pb (Huang & Cunhingham, 1996;Alves et al, 2008;Zhivotovsky et al, 2011;Gupta et al, 2013).…”

“…Other authors (Paiva et al, 2000;Boonyapookana et al, 2005;Alves et al, 2008;Pereira et al, 2010;Danh et al, 2011;Seth et al, 2011;Zhivotovsky et al, 2011;Hamadouche et al, 2012;Hamvumba et al, 2014) also found reductions of dry matter production in many plant species as a function of the application of increasing doses of Pb in experiments with soil and nutrient solution. The Pb toxicity observed in the present study is due to its action on plants, causing physiological, biochemical and structural disorders, such as disequilibrium in water and hormone balance, nutritional disorders, loss of membrane permeability, reduction of enzymatic activity, inhibition of respiration and photosynthesis, among others (Yadav, 2010;Gupta et al, 2013).…”

“…Except for hyperaccumulator species, the tendency of low translocation and mobility of Pb, with intense accumulation in the roots, has been largely documented in the literature for many plant species (Huang & Cunhingham, 1996;Alves et al, 2008;Danh et al, 2011;Zhivotovsky et al, 2011;Hamadouche et al, 2012;Hamvumba et al, 2014;Kacálková et al, 2014;Selamat et al, 2014). The intense retention of Pb in the roots is related to its high affinity to the negative charges of the cell wall, especially in external tissues (rhizodermis and cortex), and to physiological barrier of Casparian strips and plasmalemma of endodermal cells, which restrict the access of Pb to the xylem, reducing its translocation to the shoots (Zhivotovsky et al, 2011). The higher retention of heavy metal ions in the roots and the low translocation to the shoots combat the toxicity of these elements in plant species (Hossain et al, 2012;Gupta et al, 2013).…”

“…Despite having characteristics of Pb hyperaccumulator, the low dry matter production of common buckwheat does not favor its use for the technique of phytoremediation. Plants of hyperaccumulator species are characterized, in general, by the low production of biomass, which limits its use for phytoextraction (Alves et al, 2008;Zhivotovsky et al, 2011).…”

Effect of biochar amendments on As and Pb mobility and phytoavailability in contaminated mine technosols phytoremediated by Salix

“…For instance, Zhivotovsky et al (2010) observed in a hydroponic culture a higher lead concentration in roots (4164 to 14146 mg.kg -1 ) than in woody tissues (71.9 to 403.5 mg.kg -1 ), when applying Pb concentrations from 48 to 241 µM. On a biochar amended arsenic polluted soil, Beesley et al (2014) also found a higher accumulation in tomato roots.…”