There is much concern about the cleanup of toxic contaminants in the environment as human activities increase. The objective of this research was to study the effects of different rates (0, 0.3 and 0.5 g·L⁻¹) of (CuCl₂) used for irrigation and its translocation in shoots and roots of three varieties: Romaine lettuce (local), Redina lettuce (red) and iceberg lettuce (Lactuca sativa L.) after 97 days. There was a significant difference in fresh weight and dry weigh for all varieties of lettuce. Differential accumulation and translocation of copper (Cu) in the root and leaf of vegetables were investigated using atomic absorption spectrophotometer. Red plant accumulated higher amounts of Cu (1.89 mg·kg⁻¹) in root and (0.71 mg·kg⁻¹) in shoot compared to the other three plant species. The accumulation coefficient (AC) and translocation factor (TF) of Cu in three varieties was higher in red followed by local and iceberg. At high concentrations (CuCl₂: 0.5 g·L⁻¹), the light micrographs obtained from the leaf samples of copper-treated plants showed changes and a reduction in the number and the distribution of chloroplasts in palisade and spongy parenchyma cells. All cultivars were able to accumulate significant amounts of Cu, but they have severe symptoms of phytotoxicity when the copper concentration was high.

This is the first study on the performance of sour orange ( Citrus aurantium L.) in soil contaminated with chromium (Cr). A greenhouse experiment was conducted to determine the phytotoxic effect of Cr on seed germination and seedling growth of sour orange. Cr treatments were applied as Cr(NO ₃ ) ₃ in five concentrations (0, 50, 100, 150, and 200 ppm). A gradual increase in Cr concentration leads to inhibition of seed germination and other growth parameters. Phytotoxicity, relative water content (RWC), seed vigor index (SVI), and the tolerance index (TI) show a significant decrease up to 100 ppm as a result of the presence of metal. Biochemical constituents, nutrient uptake, antioxidative enzymes, and lipid peroxidation under Cr stress were also investigated. The results indicate that concentrations greater than 100 ppm Cr cause an increase in plant antioxidative enzymes—superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX)—and increased lipid peroxidation. On the other hand, sour orange effectively generated an enzymatic antioxidant defense system (especially CAT) to scavenge hydrogen peroxide (H ₂ O ₂ ), resulting in less H ₂ O ₂ in shoots with greater Cr concentrations. A majority of Cr accumulated in the shoots and low translocations to shoots. However, sour orange is the best universal rootstock for citrus because of its resistance to salinity and disease. It also grows well in heavy soils. Based on the results of this study, sour orange might be a potential candidate plant for phytofiltration of contaminated water and phytostabilization of Cr-contaminated soils.

Carrot production of valuable carotenes, carbohydrate and protein are hindered by elevated salinity levels in many parts of the world. To assess this problem, germination and growth of two carrot cultivars (Daucus carota cvs Jordan and Napoli) were studied in vivo and in vitro under different salt stress concentrations (0, 75, and 150 mM NaCl). Seeds were directly or gradually exposed to these salt concentrations. With elevated salinity levels, significant reductions in growth parameters (dry shoot weight, fresh shoot weight, shoot length, root length, and root number) were observed. Also, significant difference in germination percentage was observed at 150 mM NaCl in both cultivars when compared with control treatment (90% germination percentage in Napoli and 71% in Jordan cultivar). Growth rate, tolerant index, and relative water content (RWC) declined as salinity increased. The 150 mM NaCl salinity treatment significantly reduced the shoot chlorophyll and protein content, but increased carbohydrate content. Lesser impairment by the gradual exposure of seedling to salinity provides an opportunity to study the acquirement of salt tolerance.

Most of Jordan’s arid and semi-arid areas have suffered land degradation and a decline in plant biodiversity, making non-conventional water resources essential for enhancing dryland productivity. Olive oil production in Mediterranean countries generates large amounts of olive mill wastewater (OMW), locally known as “Zibar,” a source of environmental pollution due to its high acidity and heavy loads of polyphenols and organics. We assessed the phytotoxicity of OMW at five concentrations (0–100%) on seed germination and early seedling growth of two dryland native plants, Atriplex halimus and Achillea fragrantissima, to evaluate their suitability for revegetation of OMW-affected sites. The final germination percentage was unaffected by OMW concentration in either species, but the seedling vigor index declined significantly under treatment in both. In Achillea fragrantissima, the germination index, root length, and fresh weight were significantly reduced even at the lowest OMW concentration tested, indicating high sensitivity. In Atriplex halimus, significant reductions in shoot length and fresh weight emerged mainly at higher concentrations, indicating comparatively greater tolerance. These results suggest Atriplex halimus is a more promising candidate for further evaluation in diluted OMW reuse, while highlighting the need for species-specific testing before recommending dryland plants for OMW-affected environments.