The impact of trace metal elements (TMEs) on plants is one current pollution problem, the severity of which is increasing with industrial development, population growth and inappropriate agricultural practices. The latter can have irreversible effects on ecosystems, including species extinction, trophic chain contamination and altered human health, particularly in the case of consumed plants such as zucchini squash (Cucurbita pepo L.). This study aims to investigate the effects of nickel on various physiological and biochemical parameters of zucchini growth, with a particular focus on how this toxic metal impacts the quality of fruit that is consumed by humans. To achieve this, plants aged 45 days were grown for one month on solid media loaded with different concentrations of Ni (0, 100, 300 and 500 µM). The results showed that exposure of plants to Ni resulted in significantly altered growth and higher accumulation of Ni in the shoots (1314 µg·g⁻¹ DW) than in roots and fruits. Concerning non-enzymatic antioxidants, the results showed that Ni toxicity significantly increased total polyphenols, especially in shoots at 300 µM Ni, while flavonoid content decreased in the roots and shoots in response to Ni treatment. Our results also show that nickel tolerance in C. pepo is ensured by a combination of several mechanisms such as an increase in the content of proline. This species can survive and tolerate, to different degrees, toxic cations at concentrations up to 500 µM but with visible symptoms of toxicity such as chlorosis of the leaves. Indeed, based on thresholds of hyperaccumulation, we can qualify Cucurbita pepo as a hyperaccumulator species of nickel.

Soil contamination by trace metal elements, such as aluminum and barium, presents specific environmental risks, particularly to plant health and agricultural productivity. Excessive accumulation of these toxic elements in plant tissues can alter redox equilibrium and affect homeostasis. This study sought to examine the physiological reactions of Abelmoschus esculentus (L.) under aluminum- and barium-induced stress. The plants were exposed to multiple concentrations of Al or Ba (0, 100, 200, 400 and 600 µM) for 45 days; then, the accumulation potential of Al and Ba, oxidative damage, and antioxidative metabolism were assessed. Key findings showed a proportional distribution of the Al and Ba in roots and aerial parts of the plants, with lower accumulation in the fruits. The occurrence of oxidative damage and the involvement of antioxidant enzymes were demonstrated by increased amounts of malondialdehyde and H₂O₂, enhanced activity of superoxide dismutase, and decreased catalase activity. The study also highlighted that GSH played a primary role in Al detoxification in the roots and fruits, while phytochelatins were more active in Ba-treated plants, particularly in roots and shoots, facilitating Ba sequestration.