Heavy Metal Contamination In Plants

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Heavy metal refers to metals and metalloids that are toxic to both plants and animals even at a very low concentration. Some of these heavy metals do not perform any known physiological function in plants, such as As, Cd, Hg, Pb or Se, these are non essential metals. Others, such as Co, Cu, Fe, Mn, Mo, Ni and Zn, are essential elements required for normal growth and metabolism of plants. Essential elements can lead to poisoning when their concentration rises to beyond optimal levels [1]. Human activities, such as mining, industrial and domestic waste water and sludge, fertilizers and pesticides application to field, also atmospheric deposition are the main sources of heavy metal contamination in plants [2].
Metal contamination of agricultural
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However, further investigation on how essential and non- essential metal ions affect plant growth at different stages of development under varying environmental conditions have to be done. Seed is a stage in the plant life cycle that is well protected against various kinds of stress. However, after imbibition and during vegetative developmental processes, they become stress sensitive. Therefore seed carefully monitors external conditions such as light, temperature and nutrient in order to maintain the protective state until conditions become favourable for further developmental processes…show more content…
Plants absorb heavy metals from the subsurface of 25cm depth zone of the soil where roots of most cereal crops are located [16]. After the soil is saturated with heavy metals, more of it would be distributed in the aqueous phase and the availability of the heavy metals to plants would subsequently be increased [17]. High concentration of heavy metals in soil will increase the potential of being taken up by plants [18].
Plasma membrane of root cells is the first barrier for heavy metals entering the symplasm, any interaction of ions with the plasma membrane like negative and/or toxic effect should be first studied at the level of the plasma membrane. Metal ion toxicity on the plasma membrane is indicated via disturbed membrane functionality, lipid peroxidation and subsequent ion imbalance in the cytoplasm due to loss of ions, such as K+. Such disturbances in the plasma membrane function induce an imbalanced ion influx/efflux ratio resulting in a change in the membrane potential

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