Potential of Grasses in Phytolith Production in Soils Contaminated with Cadmium

Abstract

Cadmium (Cd) is a very toxic heavy metal occurring in places with anthropogenic activities, making it one of the most important environmental pollutants. Phytoremediation plants are used for recovery of metal-contaminated soils by their ability to absorb and tolerate high concentrations of heavy metals. This paper aims to evaluate the potential of grasses in phytolith production in soils contaminated with Cd. The experiments, separated by soil types (Typic Quartzipsamment, Xanthic Hapludox and Rhodic Hapludox), were conducted in a completely randomized design with a distribution of treatments in a 3 × 4 factorial scheme with three replications. The factors were three grasses (Urochloa decumbens, Urochloa brizantha and Megathyrsus maximus) and four concentrations of Cd applied in soils (0, 2, 4 and 12 mg kg−1). Grass growth decreased and increased Cd concentration in shoots of grasses with the increased Cd rates in soils. The toxic effect of Cd resulted in production and Cd occlusion in phytoliths produced in shoots of the grasses. Grasses showed potential for phytolith production, independent of soil type, providing phytoextraction of Cd in phytoliths. Megathyrsus maximus was the grass with the highest tolerance to Cd, evidenced by higher production and Cd capture in phytoliths for the evaluated soils. Phytolith production by grasses in Cd-contaminated soils is related to genetic and physiological differences of the evaluated grasses and Cd availability in soils.

Silicon in Plants: Alleviation of Metal(loid) Toxicity and Consequential Perspectives for Phytoremediation

“…Nguyen et al [85] and Tran et al [86] reported the encapsulation of Pb and Cu in rice and grass phytoliths, respectively. Some more studies of the accumulation of metal(loid)s in phytoliths of different plants followed recently [87][88][89][90] (details can be found in Table 1). Most recently, Liu et al [91] analyzed the encapsulation of toxic trace metal(loid)s in wheat phytoliths.…”

The mechanism of silicon on alleviating cadmium toxicity in plants: A review

“…In this process, silicon is also deposited in the leaf epidermal cell wall, which decreases the efficiency of cadmium transport ( Lux et al., 2003 ; Keller et al., 2015 ). When cadmium reaches the leaf, silica aggregates in the cell wall, as a physical barrier, suppressing cadmium from entering the cells ( Farnezi et al., 2020 ).…”

Effect of Soil Characteristics on Arsenic Accumulation in Phytolith of Gramineae (Phragmites japonica) and Fern (Thelypteris palustris) Near the Gilgok Gold Mine

“…First, trace elements in phytolith are considered as detoxified trace elements from a plant defense mechanism. For this purpose, the plant needs to accumulate trace elements in the phytolith more than in the plant body [7,10,11]. Delplace et al [7] collected reed from four mine areas and two control areas and analyzed the heavy metal concentration.…”