Cadmium and zinc removal by some cut flower plants

Abstract

From the problem statement of cadmium and zinc contamination in soil and plants in Pha Tae village, Mae Sot district, Tak Province. So it leads to an idea to use some cut flower plants such as chrysanthemum (Dendranthema difflora) marigold (Tagetes erecta L.) and globe amaranth (Gomphrena globosa L.) to cultivate in this area to uptake of cadmium and zinc from contaminated soil, moreover by product is cut flowers for the commercial purposes. The objective of this research is the study on the effects of cadmium and zinc at different levels to the growth of chrysanthemum (D. difflora), marigold (T. erecta L.) and globe amaranth (G. globosa L.) that determined by height, intemodes length, diameter of stem and dry weight. Comparing the amount of cadmium and zinc accumulation in roots, leaves and flowers including their efficiencies of cadmium and zinc removal (%) in different species of plant. Three plant species were cultivated by using treated soil with Cd(No[subscript 3]) [subscript 2]4H[subscript 2]O at the concentrations of 0, 20 40, 60, 80, and 100 mg Cd/kg soil or Zn(NO[subscript 3] [subscript 2]6H[subscript 2]O at the concentrations of 0, 50, 100, 150, 200 and 250 mg Zn/kg soil and ethylenediaminetetraacetic acid (EDTA) at 0.1 g/kg soil was added for chelation. Until flowering stage, the plants were harvested and the amount of cadmium and zinc accumulate in various parts of plants will be analyzed. The results showed that marigold (T. erecta L.) and globe amaranth (G. globosa L.) better grew up than chrysanthemum (D. difflora). Marigold (T. erecta L.) and globe amaranth (G. globosa L.) grew normally and could produce flowers under all concentrations, while chrysanthemum (D. difflora) which grew in soil with the compositions of Cd(NO[subscript 3]) [subscript 2]4H[subscript 2]O exhibited abnormal characteristics such as stunted and could not produce flowers at concentrations of 20, 40, 60, 80 and 100 mg Cd/kg soil, moreover a mild chlorosis appeared at concentration of 100 mg Cd/kg soil and chrysanthemum (D. difflora) which grew in soil with the compositions of Zn(NO[subscript 3]) [subscript 2]6H[subscript 2]O exhibited abnormal characteristics such as scorching in leaves and necrosis at concentrations of 50, 100, 150, 200 and 250 mg Zn/kg soil, moreover death of the flowers appeared at concentration of 200 and 250 mg Zn/kg soil. The results indicated that all plants tended to accumulate cadmium and zinc in leaves and stems more than roots. Furthermore at cadmium concentration of 100 mg Cd/kg soil and zinc concentrations of 250 mg Zn/kg soil, marigold (T. erecta L.) was more effective to remove cadmium and zinc from the soil at 0.019% and 0.042%, respectively. The results concluded that results concluded that marigold (T. erecta L.) and globe amaranth (G. gobosa L.) were suitable species for phytoremediation of contaminated soil because of their efficiencies in heavy metals removal and able to produce flowers under all concentrations.