Table 1.
Impact of Si-NPs on plants, where (–) indicates data are not available
| Composition; origin; size (nm) | Concentration, treatment | Composition; origin; size (nm) | Plant | Impact (in comparison to control group) | References |
|---|---|---|---|---|---|
| SiO2; commercial; (–) | 62, 125, 250, 500, 1000 µL/L, seedling soaked with NP solution | SiO2; commercial; (–) | Larix olgensis | 500 µL/L showed the best results with an increase in mean height, root length, number of lateral roots, and chlorophyll concentration | Bao-shan et al. (2004) |
| Nano-Si; commercial; (–) | 1, 2 mM, seeds germinated in Petri plate | Nano-Si; commercial; (–) | Lycopersicum esculentum | 1 mM NPs were observed to act better (in comparison to 2 mM) in the adaptation of plants under salinity stress, with improvements in root and shoot growth | Haghighi et al. (2012) |
| Nano-Si; commercial; 20–35 | 1, 2 mM, seedlings though nutrient solution | Nano-Si; commercial; 20–35 | Solanum lycopersicum | Si and Si-NP alleviated the effect of salinity stress on the fresh weight, chlorophyll concentration, photosynthetic rate, and leaf water content of the plant 1 mM Si-NPs were observed to dramatically increase the photosynthesis rate and transpiration under 50 mM salinity stress No significant differences in the other characteristics were observed between Si-NP and Si |
Haghighi and Pessarakli (2013) |
| SiO2; biological; 20–40 | 15 kg/ha, soil in field | SiO2; biological; 20–40 | Zea mays | Si-NP-treated maize was observed to contain higher silica than micro-Si-treated maize or the control Root elongation was observed to be significantly increased |
Suriyaprabha et al. (2013) |
| SiO2; commercial; < 50 | 1 mM, seeds germinated in Petri plate | SiO2; commercial; < 50 | Lens culinaris | NP improves the germination and early growth of plants under salinity stress | Sabaghnia and Janmohammadi (2015) |
| SiO2; commercial; 12 | 2,4,6,8,10,12,14 g/L, seeds germinated in Petri plate | SiO2; commercial; 12 | Lycopersicum esculentum | 8 g/L was observed to significantly enhance seed germination, mean germination time, seed germination index, seed vigor index, seedling fresh weight, and dry weight | Siddiqui and Al-Whaibi (2014) |
| Si-NP; (–), (–) | 10 ml/L, sprayed on plant | Si-NP; (–), (–) | Ocimum basilicum | NPs alleviated the impact of salinity stress | Kalteh et al. (2014) |
| SiO2; commercial; 10–30 | 10, 50, 100 mg/L, seedling through irrigation | SiO2; commercial; 10–30 | Crataegus aronia | A dose-dependent impact on alleviating drought stress was observed by increases in plant growth properties and photosynthetic pigment concentrations and decreases in xylem water potential and MDA content | Ashkavand et al. (2015) |
| Nano-Si; commercial; (–) | 1.5, 3 mM, seeds grown in pot | Nano-Si; commercial; (–) | Vicia faba | Si-NPs were observed to slightly improve flowering when compared with Si or the control | Roohizadeh et al. (2015) |
| Nano-Si; chemical; 75–125 | 10 µM, seed and seedlings, in petri plate or hydroponic | Nano-Si; chemical; 75–125 | Pisum sativum | Addition of Si-NPs together with Cr(VI) was observed to protect pea seedlings against Cr(VI) phytotoxicity NPs were observed to upregulate the antioxidant defense system in the presence of Cr(VI) |
Tripathi et al. (2015) |
| Mesoporous nano-Si; chemical; 20 | 200, 500, 1000, 2000 mg/L, seed and seedlings, in Petri plate or hydroponic | Mesoporous nano-Si; chemical; 20 | Wheat Lupin |
NPs facilitated photosynthetic activity and plant growth NPs were observed to be accumulated in different parts of treated plants following root uptake |
Sun et al. (2016) |
| Nano-Si; biological; (–) | 7.5 g/pot, seeds in pot with soil and NP | Nano-Si; biological; (–) | Rice | The expression rate of the silicon uptake genes Lsi1 and Lsi2 increased in nano-Si in comparison to the control, but was less than that in plants treated with Si ions Overall, no positive/negative impact of nano-Si on plants was observed under salinity stress |
Abdel-Haliem et al. (2017) |
| Nano-Si; chemical; 19, 48, and 202 | 1 mM, tissues, NP added in culture solution | Nano-Si; chemical; 19, 48, and 202 | Rice | Under cadmium toxicity, the survival of rice cells was observed to be dependent on the size of NPs Gene expression for Si uptake (OsLsi1) and Cd transport to vacuoles (OsHMA3) was observed to be upregulated The expression of Cd uptake genes (OsLCT1 and OsNRAMP5) was observed to be downregulated |
Cui et al. (2017) |
| SiO2; commercial; 20–30 | 0-2.5 mM, seedlings, hydroponic | SiO2; commercial; 20–30 | Trigonella foenum | Can modulate the PST transporter and, therefore, can increase the translocation of NPs/Si NPs influenced Si uptake, translocation and accumulation, the lignification of cell walls, and the formation of stress enzymes in comparison to the control or sodium silicate |
Nazaralian et al. (2017) |
| Nano-Si; chemical; 75–125 | 10 µM, seedlings, hydroponic | Nano-Si; chemical; 75–125 | Triticum aestivum | Si and Si-NPs were observed to alleviate the negative impact of UVB radiation Si-NPs were observed to be more effective than Si in alleviating the UVB impact on plants |
Tripathi et al. (2017) |
| Nano-Si; chemical; 14, 50, and 200 | 250, 1000 mg/L, seedlings, hydroponic | Nano-Si; chemical; 14, 50, and 200 | Arabidopsis thaliana | Size-dependent uptake of silica by plants was observed A decrease in plant growth was observed with the size of 50 and 200 nm, which was attributed to a high negative zeta potential (and therefore a change in pH) |
Slomberg and Schoenfisch (2012) |
| Nontransgenic and Bt-transgenic cotton | A decrease in plant height and root and shoot biomass was observed in both transgenic and nontransgenic cotton NPs were transported from root to shoot via xylem Impacts on IAA concentration and CAT and SOD activity were observed under NP treatment |
Le et al. (2014) |
TGA thermogravimetric analysis, ICP inductively coupled plasma, XRD X-ray diffractometry, FTIR Fourier transform infrared spectroscopy