Defence Mechanisms of Olive Tree (Olea europaea) under Heavy Metals Stress

Abstract

Heavy metals can bioaccumulate and biotransfer from both natural and artificial sources. Given that heavy metal concentrations above normal seriously threaten both plant and animal life, their contamination of plants and water is one of the biggest problems facing the globe today that must be addressed. In this work, we attempt to evaluate the buildup of heavy metals in the soil, their penetration into plants, and their impact on the physiological and biochemical functions of olive trees. Therefore, it was interesting to research the concentrations of heavy metals in Sidi Khaled-Derna plants and soil. Soil samples' physical and chemical properties, including pH, electrical conductivity, organic matter mass, phosphorus and nitrogen content. Random soil samples were taken from the study areas, the first area as the control (Barborg) and the second as the polluted area (Sidi Khaled). The results showed that the concentrations of metals in the soil exposed to the pollution and the trees growing in it were greater than those found in the unpolluted area and were higher than the safe recommended values. While the electrical conductivity of the same sample was above the standard range set by the World Health Organization, the pH of the polluted soil was below the normal limit. In addition, the amount of phosphorus, nitrogen, and organic matter were lower than in control. Notable decline in the activity of the studied antioxidant enzymes in trees growing in the polluted area, and all of the results indicated that the stressed olive trees had higher levels of phenolic compounds and the amino acid proline, which are believed to be markers of oxidative stress in plant cells, compared to control trees