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• Nevertheless, the effect of red bean for the remediation of chromium not studied so far. • Also, there is not any review on the citric acid- recovery within the chromium phytoremediation by the red bean. • It,s concluded that the red bean is often a possible candidate for phytoremediation of chromium contaminated soils. • Hence, the citric acid played this role through the regulation of the antioxidant system to diminish the toxicity of Chromium-VI. Chromium-VI imposed harmful morphological, physiological, and metabolic effects in plants. Soil pollution from heavy metals is one of the foremost discussed to cause the deficiency of safe food. This study aimed to research the impact of citric acid (0, 2.5 and 5 mM), singly or together, on plant growth, photosynthetic pigments, total chlorophyll, carotenoids, anthocyanine, DPPH activity, chromium uptake and translocation factor (TF) of red bean exposed to chromium-VI stress (0, 1 and 10 mM). Results showed that shoot and root lenth, fresh and dry weight, chlorophyll, carotenoids, and DPPH activity decreased under chromium, while anthocyanine increased. The increasing concentration of chromium also enhanced the chromium uptake and accumulation in plant shoota and roots. This study showed that the addition of citric acid with chromium significantly enhanced shoot and root length, fresh and dry weight, chlorophyll, carotenoids, anthocyanine, and DPPH activity in plants. The citric acid decreased the concentration and accumulation of chromium in plant shoots and roots. This means that the most increase in translocation factor value was recorded under the combined application of chromium 1 mM and citric acid 2.5 and 5 mM, as compared to the plants treated with chromium alone. It is concluded that the red bean can be a potential candidate for phytoremediation of chromium contaminated soils. Hence, the citric acid played this role through the regulation of the antioxidant system to diminish the toxicity of Chromium-VI. [ABSTRACT FROM AUTHOR]

The aim of the present study was to compare the effect of lead (Pb) exposure (0–50 mg L −1 Pb) on Pb accumulation, growth, and the concentrations of thiol compounds, organic acids, antioxidant enzyme activities and other biochemical parameters between a non-metallicolous and a metallicolous harmal ( Peganum harmala L.) population. Seedlings were grown in hydroponics, and exposed to 0, 5, 10, 25 and 50 mg L −1 Pb for 14 days. Lead decreased dry weight to the same extent in both populations, in a concentration-dependent way. Pb accumulation was consistently higher in the metallicolous population than in the non-metallicolous one, both in roots and shoots, showing that the metallicolous plants were more tolerant to plant-internal Pb. Under Pb exposure the concentrations of malondialdehyde (MDA) and H 2 O 2 , as well as the LOX and GPX activities, were higher in the non-metallicolous population, albeit inconsiderably. The activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), as well as the concentrations of the non-enzymatic antioxidants GSH, ascorbic acid, and proline, were enhanced under Pb exposure, and overall higher in the metallicolous population, though only significantly so under Pb exposure. The concentrations of total thiols, non-protein thiols and protein bound thiols were also increased under Pb exposure. In particular, Pb strongly enhanced the average protein cysteine content in both populations, but much more so in the metallicolous plants than in the non-metallicolous ones. Furthermore, Pb-exposed plants showed significantly increased concentrations of organic acids. Citrate accumulation was strongly induced under Pb exposure, particularly in the metallicolous plants, suggesting that citrate is the most obvious candidate ligand for Pb in the vacuole. Overall, the quantitatively most remarkable differences in Pb response between the populations lie in the degrees of Pb-induced accumulation of proline and protein thiol. [ABSTRACT FROM AUTHOR]

High concentrations of copper (Cu) can be extremely toxic for plant growth. Drought stress is also considered as a major environmental tension, as it reduces vegetative growth in medicinal plants. This study evaluated the singular and combined effects of several Cu concentrations (0, 50, 150, 300, and 400 mg kg−1) and various drought stresses (non-stress, moderate, and severe) on the different vegetative traits, photosynthetic pigments, essential oils (EOs) yield, and Cu accumulation (in roots, shoots, and distilled plant material) of Fumaria parviflora Lam. under field conditions. The seeds were collected from four zones (Z 1 , Z 2 , Z 3 , and Z 4) located in two mineral regions (Askari and Rabor) of Kerman, Iran. Drought and Cu, both independently and combined, suppressed plant growth by decreasing different vegetative growth parameters. The Cu concentration of 50 mg kg−1 yielded the highest values in all morphological traits and photosynthetic pigments. These included the dry weight and length of both shoot and root, chlorophyll content under non-drought stress, and carotenoid content under moderate drought stress. The growth parameters and photosynthetic pigments of F. parviflora declined sharply at Cu concentrations of 300 and 400 mg kg −1. The highest EOs yield (0.56% v/w) was obtained by applying 150 mg kg−1 Cu under moderate drought stress conditions in zones Z 3 and Z 4. In the distilled plant material, Cu concentration was almost similar to its concentration in shoots before the distillation process. Under moderate drought and up to a Cu concentration of 150 mg kg−1, the shoot growth parameters and photosynthetic pigments were slightly less than the control. Moreover, the EOs yield was at its highest, and Cu was mainly accumulated in the roots and only slightly transferred to the shoot. Therefore, to use the shoot and EOs of F.parviflora for medicinal purposes, it is recommended that this plant be cultivated under moderate drought in stressed soils at a maximum copper concentration of 150 mg kg−1. [Display omitted] • The seeds of Fumaria parviflora L. collected from two different Cu mineral zone in Iran. • Effects of Cu, drought stress and their interactive effects were evaluated on morphological traits and essential oils yield. • The highest essential oils was observed at 150 (mg/kg-1) of Cu under mild drought stress. [ABSTRACT FROM AUTHOR]