Accumulation and toxic effects of chromium and zinc in Iris pseudacorus L.

Abstract

The aim of the present study was to examine the ability of I. pseudacorus L., an ornamental macrophyte of great potential for phytoremediation, to tolerate and accumulate Cr and Zn. Plants were grown in nutritive solution with ZnCl 2 or CrCl 3 Á6H 2 O at 0, 10, 50, 100, and 200 lg ml -1 for 5 weeks; all survived and continued growing. The accumulation of Cr and Zn increased with increasing supply in all plant tissues, to reach 59.97 mg Cr and 25.64 mg Zn in roots. Leaves retained a remarkable amount of Zn (14.2 mg). Growth inhibition reached 65% and 31% (dry weight) in response to Cr and Zn, respectively. The root:shoot dry matter partitioning (R/S) increased 80% at 100 lg ml -1 CrCl 3 . The most marked alterations in mineral content were in roots, where both metals decreased Al, Ca, Mg, Mn and S, and increased P concentration. No effect was noted on either leaf chlorophyll fluorescence kinetics (F v /F m and U PSII ), or photosynthetic pigment content, signifying that the light phase of photosynthesis was not impaired. Carbon isotope composition (d 13 C) was only slightly heavier, indicating that the reduction of carbon fixation was not the main cause for growth decrease. This was attributed to the restricted mineral uptake and to the increased demand of carbohydrates of damaged roots. Biomass allocation to rhizomes (Cr) or roots (Zn) contributes to heavy metal tolerance by limiting transpiration and increasing metal-storing tissues and the surface for water and cation uptake. This species is a good candidate for Cr rhizofiltration and Zn phytoextraction.

How Soil Nutrient Availability Influences Plant Biomass and How Biomass Stimulation Alleviates Heavy Metal Toxicity in Soils: The Cases of Nutrient Use Efficient Genotypes and Phytoremediators, Respectively

“…Significant reductions in plant height, as well as in shoot and root dry weight (varying from 3.3% to 54.5%), as compared with that of the controls, were found for Typha angustifolia plants in different Cr treatments [60]. Furthermore, according to Caldelas et al (2012) [19], not only growth inhibition happened (reached 65% dry weight) under Cr toxicity conditions, but also root/shoot partitioning increased by 80%. Under Cr stress conditions, it was found that root and shoot biomass of Genipa americana L. were significantly reduced [20].…”

“…Under these conditions, plant growth and biomass are negatively affected [17][18][19][20]. According to Caldelas et al (2012) [19], not only growth inhibition happened, but also root to shoot dry matter partitioning (R/S) modified (increased 80%) at Cr toxic conditions in Iris pseudacorus L. plants. Some plant species, which may tolerate very high metal concentrations in their tissues, can be used as hyper-accumulators and are very suitable in reducing heavy metal concentrations in contaminated soils [21].…”

“…This technique involves the use of the ability of some plant species to absorb and accumulate high concentrations of heavy metal ions [17]. Some of these species may be a few ones from Brassicaceae family, such as raya (Brassica campestris L.) [17] and Thlaspi caerulescens [23], or from other families, such as spinach (Spinacia oleracea L.) [17], Sedum plumbizincicola [24], Amaranthus hypochondriacus [25], Eremochloa ophiuroides [26], Iris pseudacorus L. [19], Ricinus communis L., plant of Euphorbiaceae family [18]. Finally, the tree species Genipa Americana L. may be used as one with great ability as phytostabilizer and rhizofilterer of Cr ions, according to Santana et al (2012) [20].…”

Biomonitoring of Epilobium hirsutum L. Health Status to Assess Water Ecotoxicity in Constructed Wetlands Treating Mixtures of Contaminants

“…Plant aboveground (AG) and belowground (BG) parts were washed separately with tap water to remove particle deposition. The AG parts were not desorbed (no EDTA nor hard scrubbing) to preserve the fraction of metal adsorbed to cell walls, to enable comparison with what would happen after harvesting in CW [43]. Plant and pozzolan samples were dried at 80 °C over one week.…”

Biochemical Changes under Chromium Stress on Germinating Seedlings of <i>Vigna radiata</i>

“…Sources of heavy metal contamination include anthropogenic activities, like use of pesticides, agriculture waste and industrial waste. Hexavalant chromium is considered the most toxic form because of its high solubility in water, which usually occurs amalgamated with oxygen as chromate or dichromate (Samantaray et al, 1998, Caldelas et al, 2012Hayat et al, 2012). Cr is known to induce production of elevated concentration of ROS resulted in macromolecule damage.…”