Salinity stress poses a critical threat to global crop productivity, driven by factors such as saline irrigation, low precipitation, native rock weathering, high surface evaporation, and excessive fertilizer application. This abiotic stress induces oxidative damage, osmotic imbalance, and ionic toxicity, severely affecting plant growth and leading to crop failure. Silicon (Si) has emerged as a versatile element capable of mitigating various biotic and abiotic stresses, including salinity. This review offers a comprehensive analysis of Si's multifaceted role in alleviating salinity stress, elucidating its molecular, physiological, and biochemical mechanisms in plants. It explores Si uptake, transport, and accumulation in plant tissues, emphasizing its contributions to maintaining ionic balance, enhancing water uptake, and reinforcing cell structural integrity under saline conditions. Additionally, this review addresses Si transformations in saline soils and the factors influencing its bioavailability. A significant focus is placed on silicon-solubilizing microorganisms (SSMs), which enhance Si bioavailability through mechanisms such as organic acid production, ligand exchange, mineral dissolution, and biofilm formation. By improving nutrient cycling and mitigating salinity-induced stress, SSMs offer a sustainable alternative to synthetic silicon fertilizers, promoting resilient crop production in salt-affected soils.

Salinity is a common environmental stress that disrupts physiological and biochemical processes in plants, inhibiting growth. Silicon is a key element that enhances plant tolerance to such abiotic stresses. This study examined the effects of silicon supplementation on physiological, biochemical, and molecular responses of GF677 and GN15 rootstocks under NaCl-induced salinity stress. The experiment was conducted in a greenhouse using a factorial design with two rootstocks, three NaCl concentrations (0, 50, and 100 mM), and three silicon levels (0, 1, and 2 mM) in a randomized complete block design with three replicates. Salinity significantly reduced growth parameters, including shoot and root fresh and dry weights, RWC, and photosynthetic activity, with GN15 being more sensitive to salt stress than GF677. Silicon supplementation, especially at 2 mM, alleviated NaCl-induced damage, enhancing biomass retention and RWC under moderate and high NaCl levels. Additionally, silicon reduced electrolyte leakage, lipid peroxidation, and hydrogen peroxide accumulation, suggesting a protective role against oxidative stress. Biochemical analyses showed that silicon increased the accumulation of osmolytes such as proline, soluble sugars, glycine betaine, and total soluble protein, particularly in GF677. Silicon also boosted antioxidant enzyme activities, mitigating oxidative damage. In terms of mineral nutrition, silicon reduced Na+ and Cl- accumulation in leaves and roots, with the greatest reduction observed at 2 mM Si. Gene expression analysis indicated that NaCl stress upregulated key salt tolerance genes, including HKT1, AVP1, NHX1, and SOS1, with silicon application further enhancing their expression, particularly in GF677. The highest levels of gene expression were found in plants treated with both NaCl and 2 mM Si, suggesting that silicon improves salt tolerance by modulating gene expression. In conclusion, this study demonstrates the potential of silicon as an effective mitigator of NaCl stress in GF677 and GN15 rootstocks, particularly under moderate to high salinity conditions. Silicon supplementation enhances plant growth, osmotic regulation, reduces oxidative damage, and modulates gene expression for salt tolerance. Further research is needed to assess silicon's effectiveness under soil-based conditions and its applicability to other rootstocks and orchard environments. This study is the first to concurrently evaluate the physiological, biochemical, and molecular responses of GF677 and GN15 rootstocks to silicon application under salt stress conditions.

Silicon nanoparticles (SiNPs) have emerged as multifunctional tools in sustainable agriculture, demonstrating significant efficacy in promoting crop growth and enhancing plant resilience against diverse biotic and abiotic stresses. Although their ability to strengthen antioxidant defense systems and activate systemic immune responses is well documented, the fundamental mechanisms driving these benefits remain unclear. This review synthesizes emerging evidence to propose an innovative paradigm: SiNPs remodel plant redox signaling networks and stress adaptation mechanisms by forming protein coronas through apoplastic protein adsorption. We hypothesize that extracellular SiNPs may elevate apoplastic reactive oxygen species (ROS) levels by adsorbing and inhibiting antioxidant enzymes, thereby enhancing intracellular redox buffering capacity and activating salicylic acid (SA)-dependent defense pathways. Conversely, smaller SiNPs infiltrating symplastic compartments risk oxidative damage due to direct suppression of cytoplasmic antioxidant systems. Additionally, SiNPs may indirectly influence heavy metal transporter activity through redox state regulation and broadly modulate plant physiological functions via transcription factor regulatory networks. Critical knowledge gaps persist regarding the dynamic composition of protein coronas under varying environmental conditions and their transgenerational impacts. By integrating existing mechanisms of SiNPs, this review provides insights and potential strategies for developing novel agrochemicals and stress-resistant crops.

Cadmium (Cd) is a pervasive phytotoxic metal which deteriorates soil quality, affecting crops and creating adverse effects on the environment, food safety, and human health. Cd in soil poses negative effects on plants at the physiological, structural, and molecular level. Application of silicon (Si) can reduce Cd accumulation by suppressing Cd uptake in plants, while spermidine (Spd) alleviates Cd toxicity through improved antioxidant capacity. However, their combined effects on antioxidant system and endogenous polyamines (PAs) level in Cd-stressed plants and the underlying antioxidative defense mechanism are poorly understood. Salix matsudana Koidz. is a fast-growing tree species with high Cd tolerance, making it potentially suitable for phytoremediation. Here, the S. matsudana seedings were subjected to 50 mu M Cd stress with or without addition of 1.5 mM sodium silicate and 0.1 mM Spd. Following that, the non-enzymatic/enzymatic antioxidants, stressed-related genes and endogenous PAs levels were determined. The results showed that Cd stress suppressed the growth traits of S. matsudana while increasing reactive oxygen species (ROS) and malondialdehyde (MDA) accumulation in the leaves, which also showed heightened Cd levels. However, exogenous application of Si and Spd increased activities of antioxidative enzymes and ameliorated the Cd-induced oxidative damage. Moreover, combined treatment with Si and Spd showed higher glutathione (GSH) and GSH/GSSH (oxidized glutathione) ratio compared to their individual applications. The results provided sufficient evidence regarding the synergistic effect of Si and Spd in the amelioration of Cd-induced oxidative stress in S. matsudana seedlings.

Societal Impact StatementIntervention strategies that involve supplementing crop-lands with silicon have significant scope for carbon capture and drought mitigation, offering wide-ranging societal impacts. These include contributing to decarbonisation goals, enhancing food security, providing economic benefits and reducing environmental damage associated with intensive agronomic practices. This article highlights emerging evidence that suggests elevated atmospheric CO2 and water limitation may impair silicon accumulation in plants. While this does not negate the outlined societal benefits, we argue that these limitations must be thoroughly quantified and incorporated into large-scale implementation plans to ensure the reliability and effectiveness of silicon intervention strategies. Silicon accumulation in plants is increasingly recognised as playing an important functional role in alleviating environmental stresses. Most research to date has focussed on relieving agronomic stresses in crops, including pest and pathogen damage, soil salinity and drought. Recently, attention has turned to large-scale silicon application to agricultural landscapes as a potential anthropogenic climate change mitigation strategy. This includes silicon fertilisation to enhance soil carbon storage through advanced weathering of silicates, or by incorporating carbon in phytoliths in plant tissues. While these geoengineering approaches have potential, they could also present significant challenges. This article explores the opportunities and limitations for silicon-based interventions in mitigating the impacts of rising atmospheric carbon dioxide levels and increased incidences of drought. We argue that despite the promise of silicon supplementation in reducing plant stress under climate change, research paradoxically shows that these very climate conditions can significantly impede silicon accumulation in plants. We propose a framework to guide the development of silicon intervention strategies to mitigate climate change and the research questions that should be addressed to ensure their effectiveness under future environmental conditions.

This study focused on synthesizing polyvinyl alcohol (PVA) utilizing glutaraldehyde (GA) as a crosslinking agent and silicon dioxide (SiO2) nanopowder with titanium dioxide (TiO2) nanopowder to reduce or prevent the hydrophilic property of PVA. Integrating SiO2 and TiO2 into the PVA boosted the hydrophobicity, thermal properties, and self-cleaning of the PVA film. The characteristic properties of PVA/GA, PVA/SiO2/GA, and PVA/SiO2/TiO2/GA nanocomposites polymer membranes were investigated by gel content, swelling capacity, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction patterns (XRD), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), and contact angle. The resulting PVA/5%SiO2/1%TiO2/GA nanocomposite exhibits much better physical properties than PVA/GA hydrogel (water absorbency from 3.1 g/g to 0.07 g/g and contact angel from 0 degrees to 125 degrees). In addition, the nanocomposite retains very low swelling properties. These prepared nanocomposites are promising in a variety of applications such as sand soil stabilizers, construction, and building works where they exhibit excellent water resistance performance. This study introduces a novel approach for creating hydrophobic polymeric membranes from hydrophilic polymeric materials to stabilize sandy soil effectively.

Excessive boron (B) levels in soil can lead to toxicity in plants, impacting their growth and productivity. Effective strategies to reduce B uptake are important for improving crop performance in contaminated soils. This experiment aimed to investigate the effects of chicken manure incineration ash (CMA) and triple superphosphate (TSP) on B uptake in barley plants grown in B-contaminated soil. Before the experiment, the chemical composition and molecular structure of CMA were analyzed using XRF, XRD and SEM. The soil was contaminated with 15 mg kg-1 of B, and both TSP and CMA were applied at rates of 40, 80, and 160 mg kg-1 of phosphorus (P). Neither P source had a significant impact on plant dry weight. However, increasing doses of applied TSP and CMA increased plant P concentration while significantly decreasing B concentration. Particularly with CMA applied at 160 mg kg-1 P dose, plant B concentration decreased to the lowest level of 194 mg kg-1. Increasing P doses led to a slight decrease in plant silicon (Si) concentration. The pH of soil samples taken after the experiment slightly increased with CMA treatments compared to TSP. The available P concentration in soils increased with increasing P doses. The available B concentration decreased with increasing P doses, especially reducing to the lowest level of 2.52 mg kg-1 in soils with a 40 mg kg-1 P, CMA. In conclusion, in addition to the effect of P, the molecular structure of P is also important in reducing B uptake in barley.

Juglans sigillata, an endemic species in China, serves as a vital local economic resource. Aluminum (Al) stress caused by soil acidification can potentially threaten the growth of J. sigillata. This study aimed to elucidate the mechanism of the alleviation of Al stress by silicon (Si) in J. sigillata. The results showed that Si could reduce the Al accumulation of walnut and improve root growth under Al stress. Si also increased peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities and soluble sugar and proline contents, reduced malonaldehyde (MDA) and H2O2 contents and the O2- production rate, and maintained the homeostasis of cells. Transcriptome analysis revealed significant up-regulation of genes encoding plant hormones (ABA, IAA, and CTK) and photosystem II components (PsbO, PsbQ, PsbW, and PsbY). Under Al stress conditions, the application of exogenous Si notably enhanced the expression of genes associated with heavy metal transport (CAX, PAA, ABC, HMA, NRAMP, and ZIP). Comprehensive transcriptome and metabolomics analysis showed that Si regulated secondary metabolite metabolism via the phenylalanine, galactose, and tryptophan pathway, altered cell wall composition, increased energy supply, and reduced auxin synthesis in root tip transition zones to alleviate Al toxicity of J. sigillata. In summary, the application of Si significantly alleviated Al-induced damage in J. sigillata.

Large quantities of hazardous heavy metals found in industrial wastes and are adequate to make crops toxic and these noxious metals accumulate in plant tissues can cause deleterious effects in plants. The current investigation was carried out to assess the physiological response of onion plants in textile effluents contaminated soil and to determine the role of silicone in the onion plant under oxidative stress. The industrial effluent was used at the rate of control, 30 %, 60 % and 100 % effluents. Following treatment applications were made (30 % +Si, 60 % +Si, 100 % effluents + Si,0 % +Si). Various physiological and enzymatic parameters were studied. The complete randomized design (CRD) with triplicates was used for the experiment. Treatment T4 (seed + 100 % effluents) was most toxic and 43 % shoot length, 51 % root length, 47 % membrane damage,74 % chlorophyll a,67 % chl b, 82 %carotenoids, and 44 %, catalase inhibition was observed over (T1). Similarly, MDA content and membrane damage were also higher in T4 (237,189 %) as control. The (seed+ Si) was found most effective in terms of onion growth which increased the shoot length, root length, chl a, chl b, carotenoids, and SOD (34, 51,70,284, 175, and 174 %) higher as compared to T1 respectively. It is concluded from the current investigation that textile effluents contain various toxic materials, especially heavy metals which can adversely affect the onion plant and silicon suppressed the toxicity of effluents in plant, Si can be used l to overcome toxic effect of industrial waste and plant growth promotion

Fluoride, a highly phytotoxic and nonessential element in higher concentrations is a major concern in decreasing wheat production. In the present study, we examined the ability of silicon, a semi-essential element which helps to mitigate the detrimental effects of various environmental stresses in overcoming fluoride-mediated toxicity in wheat cultivars. The seeds of two wheat cultivars, tolerant (Raj 4120) and susceptible (Raj 4238), were grown in soil supplemented with NaF (0, 400, and 500 mg kg-1) and then supplied with silicon (0, 200, and 300 mg kg-1) as Na2SiO3 at 10th days of germination with 160 mu mol quanta m-2 s-1 of photon density, 16-h photoperiod, and 55-60% relative humidity at 25 +/- 2 degrees C. The fluoride stress led to oxidative damage in roots, as evidenced by the significant elevation in MDA and H2O2 content in both wheat cultivars and decreased major components of the suberin and cesA4 gene expression in roots, which together can negatively impact the rigidity and strength of the cell wall. Conversely, the application of silicon had a beneficial effect in both wheat cultivars with and without fluoride stress. Silicon decreased the MDA and H2O2 content levels and increased the antioxidant defence system. Interestingly, Si was able to partially reverse F stress in both the wheat cultivars by increasing suberin deposition on the endodermis and promoting secondary cell wall synthesis gene expression in roots. The present study concluded that soil application of silicon can be a useful approach in protecting wheat from fluoride toxicity.