Silicon (Si) effects on mineral nutrient status in plants are not well investigated. It is known that Si has a beneficial effect on plants under stressed conditions. The aim was to make a state of the art investigation of the Si influence: (1) on nutrient availability in four different soil types, namely clayish, sandy, alum shale and submerged soil; and (2) on accumulation of various nutrients in maize, lettuce, pea, carrot and wheat growing in hydroponics. Soil was treated with K₂SiO₃ corresponding to 80 and 1000 kg Si ha⁻¹ and the nutrient medium with 100, 500, 1000 and 5000 μM Si. In general, Si effects were similar in all analyzed plant species and in all soil types tested. Results showed that, in soil, Si increased the availability of Ca, P, S, Mn, Zn, Cu and Mo and that of Cl and Fe tended to increase. The availability of K and Mg was not much affected by Si. Uptake from solution of S, Mg, Ca, B, Fe, and Mn increased; N, Cu, Zn and K decreased; P decreased/increased; and Cl and Mo was not influenced. Translocation to shoot of Mg, Ca, S, Mn, and Mo increased; Fe, Cu and Zn decreased; and K, P, N, Cl and B was not affected. It was concluded that, if plants had been cultivated in soil, Si-maintained increased availability of nutrients in the soil solution would probably compensate for the decrease in tissue concentration of those nutrient elements. The study shows that Si also influences the nutrient uptake in non-stressed plants.

This paper reviews the most recent progress in exploring silicon-mediated resistance to herbivorous insects and the mechanisms involved. The aim is to determine whether any mechanism seems more common than the others as well as whether the mechanisms are more pronounced in silicon-accumulating than non-silicon-accumulating species or in monocots than eudicots. Two types of mechanisms counter insect pest attacks: physical or mechanical barriers and biochemical/molecular mechanisms (in which Si can upregulate and prime plant defence pathways against insects). Although most studies have examined high Si accumulators, both accumulators and non-accumulators of silicon as well as monocots and eudicots display similar Si defence mechanisms against insects.

Silicon (Si) was long listed as a non-essential component for plant growth and development because of its universal availability. However, there has been a resurgence of interest in studying the underlying uptake and transport mechanism of silicon in plants because of the reported dynamic role of silicon in plants under stressed environmental conditions. This uptake and transport mechanism is greatly dependent upon the uptake ability of the plant’s roots. Plant roots absorb Si in the form of silicic acid from the soil solution, and it is moved through different parts of the plant using various influx and efflux transporters. Both these influx and efflux transporters are mostly found in the plasma membrane; however, their location and pattern of expression varies among different plants. The assessment of these features provides a new understanding of different species-dependent Si accumulations, which have been studied in monocots but are poorly understood in other plant groups. Therefore, the present review provides insight into the most recent research exploring the use of Si transporters in angiosperms and cryptogams. This paper presents an extensive representation of data from different families of angiosperms, including monocots and eudicots. Eudicots (previously referred to as dicots) have often been neglected in the literature, because they are categorized as low/intermediate Si accumulators. However, in this review, we attempt to highlight the accumulating species of different plant groups in which Si uptake is mediated through transporters.

We have found that aquatic plants can reduce the content of perfluorinated alkyl substances (PFAS) within a short period of time. The aim of this study was to determine the variation in the uptake of PFAS from contaminated water by various wetland plant species, investigate the effect of biomass on PFAS removal, and determine whether laccases and peroxidases are involved in the removal and degradation of PFAS. Seventeen emergent and one submerged wetland plant species were screened for PFAS uptake from highly contaminated lake water. The screening showed that Eriophorum angustifolium, Carex rostrata, and Elodea canadensis accumulated the highest levels of all PFAS. These species were thereafter used to investigate the effect of biomass on PFAS removal from water and for the enzyme studies. The results showed that the greater the biomass per volume, the greater the PFAS removal effect. The plant-based removal of PFAS from water is mainly due to plant absorption, although degradation also occurs. In the beginning, most of the PFAS accumulated in the roots; over time, more was translocated to the shoots, resulting in a higher concentration in the shoots than in the roots. Most PFAS degradation occurred in the water; the metabolites were thereafter taken up by the plants and were accumulated in the roots and shoots. Both peroxidases and laccases were able to degrade PFAS. We conclude that wetland plants can be used for the purification of PFAS-contaminated water. For effective purification, a high biomass per volume of water is required.

Floating treatment wetlands (FTWs), consisting of vegetated rafts, may reduce heavy metal levels in polluted water, but the choice of plant species for efficient metal removal needs to be further investigated. We screened the capacity of 34 wetland plant species to remove metals dissolved in water to identify suitable species for FTWs. The plants were grown hydroponically for 5 days in a solution containing 1.2 µg Cd L⁻¹, 68.5 µg Cu L⁻¹, 78.4 µg Pb L⁻¹, and 559 µg Zn L⁻¹. Results show large variation in metal removal rate and capacity between the investigated species. The species with highest removal capacity could remove up to 52–94% of the metals already after 0.5 h of exposure and up to 98–100% of the metals after 5 days of exposure. Plant size contributed more to high removal capacity than did removal per unit of fine roots. Carex pseudocyperus and C. riparia were the most efficient and versatile species. The findings of this study should be considered as a starting point for further investigation of plant selection for improved water purification by FTWs.