Accumulation and distribution pattern of lead and cadmium and their effect on vegetative and reproductive traits of Corchorus olitorius
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Date
2020
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University of Zululand
Abstract
Lead and cadmium heavy metal toxicity are some of the major concerns on agriculture because they can enter the food chain through the consumption of contaminated vegetables and cause serious health issues to humans. Corchorus olitorius L. is a wild leafy vegetable that can be harvested from areas such as roadsides and mining areas, which are prone to contamination by these heavy metals. However, limited studies focus on determining the effect of toxic Pb and Cd accumulation on morphological features of wild edible plants. C. olitorius seeds were sown in potted soil treated with 0, 5, 10, 15, 20 and 25 mg kg‒1 Cd(NO3)2 and 0, 150, 300, 600, 900, and 1000 mg kg‒ 1 Pb(NO3)2. The experiment was arranged in a randomized complete block design and each concentration had five replications. Differences in germination percentage, seedling mortality, vegetative and reproductive traits were recorded among treatments. Harvested immature and mature plants were separated into leaves, stems, and roots; dried and grounded into powder; and analyzed for heavy metal accumulation using Atomic Absorption Spectroscopy (AAS) and Scanning
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Electron Microscopy (SEM) in combination with Energy Dispersive X-ray (EDX) techniques. Concentrations up to the maximum of 600 mg kg–1 Pb and 10 mg kg–1 Cd soil treatments resulted in toxic accumulation of these heavy metals in different plant parts, but either promoted or did not affect germination percentage, seedling growth, as well as vegetative and reproductive traits, when compared with the control. Pb was relatively restricted to and highly accumulated in the roots, whereas Cd was easily translocated and was concentrated in the aerial parts. In three and two informative principal components of morphological and accumulation analyses, respectively, almost all investigated traits were associated with principal component one which had the highest variability. The biplots and dendrograms in both analyses mainly grouped Pb and Cd treatments into separate clusters. Results of metal accumulation analysis using both AAS and SEM coupled with EDX techniques were complementary to each other. C. olitorius is a potential plant for the use in the phytoremediation of Pb and Cd contaminated soils but is toxic for harvest and consumption from such areas.
Description
A dissertation submitted in fulfillment of the academic requirements for the degree of Master of Science in the Department of Botay in the Faculty of Science, Agriculture and Engineering, University of Zululand, 2020
Keywords
Lead and cadmium, Vegetative and reproductive traits, Corchorus olitorius