Effects of Lead, Copper and Cadmium on Bioaccumulation and Translocation Factors and Biosynthesis of Photosynthetic Pigments in Vicia faba L. (Broad Beans) at Different Stages of Growth

Abstract

Trace elements in the environmental media contribute to toxicities of different types. Their presence in the arable pedosphere is a human-health risk factor. This study focused on Vicia faba represented by two Tunisian varieties of bean (Mamdouh) and faba bean (Badii). The objective was to analyze the effects of lead, copper and cadmium on their growth, chlorophyll-content and carotenoids-content, as well as the bioaccumulation and translocation factor, at different stages of growth. For each metal, the concentrations the plants were subjected to were 6, 0.3 and 0.03 mg/L of the metal in the compound for lead nitrate, copper nitrate and cadmium acetate, respectively. The analysis was carried out using an atomic absorption spectrophotometer (ICP-MS), encompassing all the parts of the plant. The authors detected a perceptible decrease in the fresh weight of roots and shoots, as well as a drop in the chlorophyll and carotenoid, for all the three heavy metals. Cadmium turned out to be the most toxic of the three metals and copper (which is incidentally an essential micronutrient for plant growth) the least. As far as the bioaccumulation factor was concerned, bean and faba bean exhibited different behaviours, both with regard to the growth stages and the heavy metal absorbed. During the vegetative growth stage, both were accumulators of all the three heavy metals (a translocation factor less than unity). However, in the flowering stage, faba bean was a hyper-accumulator of copper (TF > 1); while the bean plants accumulated a lot of lead in the pods-stage (TF > 1). It is worthwhile to pose new research questions and try to answer them in this study, if legumes are accumulator or hyper accumulator plants in which stage and in where organ accumulate more HMs.

Accumulation and Chemical Forms of Cadmium in Tissues of Different Vegetable Crops

“…Due to the complex dynamic interaction among heavy metals, soil, and organisms, only some of the heavy metals in the soil can be bio-absorbed and assimilated [21]. The migration and transformation of heavy metals in the soil varied with the available state or occurrence form [22], and their biological effectiveness on plants also differed [23]. However, previous research on heavy metals in soil mostly focused on the total content level, which do not accurately reflect the actual ecological risk of heavy metals pollution.…”

Lead and copper removal from sterile dumps by phytoremediation with Robinia pseudoacacia

“…syl-vestris 44 , 45 and contrary to the results obtained by Brun et al 46 as regards the Cu accumulation in aerial parts in the case of maise . Another study in which high values of Cu were identified in two Tunisian varieties of bean (Mamdouh) and faba bean (Badii) suggested that Cu is readily translocated to the aerial parts of the plants, owing to its role in plant metabolism because after all, it is a necessary micronutrient 47 . Moreover, the high bioavailability of Cu is possibly due to its high solubility under acidic conditions as free water ions as reported in the case of Cd 48 .…”