Effects of winter and summer conditions on Cd fractionation and bioavailability, bacterial communities and Cd phytoextraction potential of Brachiaria decumbens and Panicum maximum grown in a tropical soil

Are Grasses Really Useful for the Phytoremediation of Potentially Toxic Trace Elements? A Review

“…for example B. decumbens and P. maximum (Rabêlo et al, 2020a). Thus, the use of such plants for trace element phytoextraction is feasible only in mildly polluted agricultural soils, otherwise trace element-induced phytotoxicity will prevent further growth and biomass yield.…”

“…The greatest number of studies have been undertaken with the grasses of the genera Phragmites, Lolium, Sorghum, and Festuca are because of their large geographical distribution globally, extending from cold regions to humid wetlands in the tropics (Zeven and de Wet, 1982), and their higher tolerance to trace elements exposure. However, the potential of each grass species for trace element phytoremediation depends on several factors such as trace element bioavailability (Rabêlo et al, 2020a), the mechanisms involved in the uptake, transport, accumulation, toxicity, tolerance to each trace element (Sipos et al, 2013), and the cultivation system (Tordoff et al, 2000;Vymazal and Březinová, 2016), among other factors. This review aims to (i) to synthesize the available information concerning the mechanisms involved in the uptake, transport, accumulation, toxicity, and tolerance to trace elements in grasses; (ii) to identify suitable grasses for phytoextraction, phytostabilization, and phytofiltration; (iii) to describe the main strategies used to improve the phytoremediation efficiency by grasses; and (iv) to point out advantages, disadvantages, and perspectives for the use of grasses for phytoremediation of polluted soils.…”

Unraveling the mechanisms controlling Cd accumulation and Cd‐tolerance in Brachiaria decumbens and Panicum maximum under summer and winter weather conditions

“…Besides the effects on the physiological processes involved in Cd uptake, the different conditions of the season influence also Cd bioavailability from the soil (Jia et al 2018). The bioavailability of Cd in our soil was 34% higher in winter conditions compared to summer conditions (Rabêlo et al 2020) enabling both grasses to take up more Cd in the winter than the summer conditions (Fig. 2A–C).…”

“…Although several studies have been conducted with B. decumbens and P. maximum in hydroponics (Kopittke et al 2010, Santos et al 2011, Rabêlo et al 2017a, 2017b, 2018b, 2018c, 2018d, 2019), the mechanisms of these species to cope with Cd‐stress are still poorly understood (Rabêlo et al 2018a). Moreover, in soils, Cd is not as easily available as in hydroponic systems (Rabêlo et al 2020). As the roots are the first in contact with Cd, an important defense mechanism against Cd‐induced stress is associated with the plant capacity to decrease or delay the Cd transport through membranes (from the apoplast to symplast) in the root cells, enabling the activation of intracellular Cd detoxification mechanisms (Wójcik et al 2005, Rabêlo et al 2017a, Song et al 2017,Clemens 2019, Andresen et al 2020).…”

“…cv. Massai tolerated very high Cd concentrations in hydroponics (Kopittke et al 2010, Santos et al 2011, Rabêlo et al 2017a, 2017b, 2017c, 2018b, 2018c, 2018d, 2019, 2020). However, the mechanisms that allow them to cope with Cd‐induced stress are still poorly understood, especially under environmentally realistic conditions.…”