Zinc Accumulation in Amaranthus caudatus and Corchorus olitorius: Relevance for Phytoextraction

Aim: In a pot experiment the accumulation of zinc in Amaranthus caudatus and Corchorus olitorius from contaminated soil and its relevance for phytoextraction were studied.

Study Design: Plants were exposed to three levels of zinc concentration as zinc sulphate heptahydrate (0,150, 300, 450 ppm), laid in completely randomized design.

Place and Duration of Study: The study lasted for a total of 37 days in a housing facility used for phytoplankton culture at National Institute for Freshwater Fisheries Technology New-Bussa Nigeria.

Materials and Methods: Seeds were raised in a nursery for 16 days, and transplanted to pots containing each 2 kg of air-dried and sieved soil. Zinc was artificially applied to soil for each vegetable. They were watered at 60-70 % field capacity and growth parameters measured every 7 days. Plants were carefully uprooted after 3 weeks of transplanting, washed, and weighed before and after oven drying. They were analyzed for zinc concentration.

Results: Results of this study showed decreases in growth and yield at 300 and 450 ppm zinc concentrations. Plant height for both vegetables increased at 150 ppm however these increases were significantly different (P≤0.05) with control for Corchorus only. There were also significant differences (P≤0.05) between treatments in zinc accumulation. Results further showed that zinc was accumulated in the leaves more than the roots. Concentrations of zinc in plant tissues of both vegetables followed a similar order of leaves > roots > stem indicating their efficiency in zinc translocation from roots to leaves. Translocation factors were generally greater than unity.

Conclusion: Despite their lack of hyperaccumulation properties, both vegetables exhibited good potential for phytoextraction. The higher translocation factor of C. olitorius indicated better phytoextraction potential.