Silicon Helps Wheat Beat Salt Stress, But Only in the Right Cultivar and Form

Salt is quietly strangling global agriculture. Roughly 20 percent of the world’s arable land is now affected by salinity, a condition that depresses wheat yields by an estimated 28 percent and maize yields by more than half. As irrigation practices and climate change push salty water ever deeper into productive soils, researchers are racing to find cheap, scalable ways to keep crops growing where sodium ions would otherwise poison them. A new study published in Plant and Soil offers both a promising lead and a sobering caveat: silicon supplementation can dramatically cushion wheat against salt stress, but only when the right silicon formulation is matched to the right wheat cultivar.

The research, led by Jannatul Ferdous and colleagues at the Hawkesbury Institute for the Environment at Western Sydney University, set out to resolve a long-standing inconsistency in the plant science literature. Numerous studies have reported that silicon alleviates salinity stress in crops ranging from rice and tomato to maize and wheat, yet others have found the benefits negligible or absent. The team suspected that much of this confusion stemmed from experimental designs that tested only a single silicon source and a single genotype, making it impossible to separate the effects of silicon chemistry from those of plant genetics.

To untangle these variables, the researchers ran a fully factorial glasshouse experiment of unusual scale. Ten commercially relevant Australian wheat cultivars, including Ballista, Calibre, Catapult, Coolah, Coota, EGA Gregory, Elmore CL Plus, Mace, Scepter and Sunflex, were grown under saline and non-saline conditions and treated with one of three silicon regimes: a granular amorphous silica derived from diatomaceous earth, a liquid formulation of the same amorphous silica, and a liquid potassium silicate solution. Each silicon treatment was paired with an appropriate matched control, including a potassium chloride control to isolate the effect of silicon from that of potassium alone. With ten replicates per combination, the experiment encompassed a total of 1,000 plants.

The baseline damage inflicted by salt was substantial and consistent with the broader literature. Salinity reduced root biomass by an average of 35.6 percent and shoot biomass by 25.6 percent across the ten cultivars under silicon-free conditions, though the severity varied considerably between genotypes. Salt stress imposes a double burden on plants: it makes water harder to extract from the soil, creating an osmotic drought, and it allows sodium ions to accumulate in shoots, where they disrupt nutrient uptake, enzyme function and cellular ion balance. Sodium is considered the dominant culprit in cereals, which is why strategies that limit its movement into above-ground tissue are so valuable.

What happened next was striking. Where silicon worked, it worked spectacularly. Root biomass responses under salinity ranged from a 51.4 percent decline in Ballista supplied with granular amorphous silica to a 113.8 percent gain in Scepter supplied with liquid amorphous silica. Shoot responses were even more dramatic, spanning from a 71.7 percent reduction in Coolah with granular silicon to a 133 percent increase in EGA Gregory receiving the liquid formulation. In other words, the same element, applied to the same species under the same stress, could either nearly double a plant’s growth or actively worsen its decline, depending entirely on the cultivar and the delivery form.

Across the board, liquid silicon formulations proved the most reliable performers. Liquid amorphous silica produced the clearest benefits under both saline and non-saline conditions, boosting root and shoot biomass by an average of 29.6 percent and 21.1 percent respectively under non-saline conditions, while liquid potassium silicate delivered moderate but consistent root protection. The granular form, by contrast, was erratic, producing strong gains in some cultivars such as Scepter but pronounced negative effects in others, including Coolah and Ballista. The researchers attribute this pattern to release kinetics: soluble silicates are immediately bioavailable to plant roots, whereas granular amorphous sources must dissolve slowly before plants can access them. In a short-term experiment where salt stress was imposed after establishment, that timing mismatch appears decisive, and it hints that granular products might perform better in field settings where gradual dissolution aligns with crop development.

The mechanistic heart of the study lies in its sodium measurements. The team quantified foliar silicon and sodium concentrations using energy-dispersive X-ray fluorescence, validating the sodium readings against a conventional microwave digestion and flame photometry method in a targeted subset of 80 samples, with strong agreement between the two approaches. In EGA Gregory, the cultivar that showed the strongest silicon-mediated rescue of shoot growth under salinity, liquid amorphous silica slashed shoot sodium concentrations from 8.07 to 2.51 milligrams per gram of dry weight. In Calibre, a cultivar that derived little biomass benefit from silicon, no significant sodium reduction was detected. Across all ten cultivars, five showed significant negative correlations between foliar silicon and sodium, meaning that plants accumulating more silicon tended to accumulate less sodium.

These findings support an increasingly refined model of how silicon protects plants from salt. Rather than acting as a simple growth stimulant, silicon appears to function as a modulator of ion homeostasis. Silicon deposited in the root apoplast is thought to reinforce endodermal barriers through suberisation and lignification, reducing the bypass flow of sodium that would otherwise stream unchecked into the shoot. Related work in maize has shown that silicon up-regulates sodium efflux genes such as SOS1 and SOS2 while promoting sequestration of sodium into leaf vacuoles, effectively shielding the photosynthetic machinery from ionic toxicity. Intriguingly, the study found that total foliar silicon concentration did not predict biomass recovery, suggesting that the functional benefit depends on where silicon is deposited, particularly in root barriers, rather than how much accumulates in bulk tissue.

Perhaps the most consequential discovery is the decoupling of salinity sensitivity from silicon responsiveness. Cultivars that were naturally more salt-tolerant did not necessarily gain more from silicon supplementation, and the two traits appear to be governed by largely independent genetics. The authors highlight a particularly instructive comparison: Coolah was directly derived from EGA Gregory, yet the two cultivars responded in opposite directions, with EGA Gregory benefiting substantially from silicon while Coolah was unaffected or even harmed. For breeders and agronomists, this means that blanket recommendations for silicon fertilisation are unlikely to succeed. Instead, the study points toward an integrated strategy in which cultivar selection is paired with targeted, genotype-specific silicon management.

The implications extend well beyond wheat. Silicon is abundant, non-toxic and environmentally benign, making it an attractive alternative to approaches with heavier trade-offs, such as costly irrigation schemes, slow breeding pipelines or osmo-protectants that are impractical at scale, especially for resource-poor farmers. Yet the study also tempers enthusiasm with realism. Liquid silicates are more expensive than granular products, and their economic viability will depend on whether the yield protection they provide under salinity justifies the input costs. What the research delivers is something the field has lacked: a mechanistic and predictive framework for when silicon fertilisation will actually work. By linking sodium exclusion to biomass rescue, and by exposing the decisive roles of genotype and formulation, the study transforms silicon from a folk remedy of uncertain reliability into a precision tool, one that could help farmers coax productive harvests from soils that salt has claimed.

Subject of Research: Silicon-mediated alleviation of salinity stress in wheat through reduced sodium accumulation

Article Title: Silicon-mediated alleviation of salinity stress in wheat is linked to reduced sodium accumulation but depends on cultivar and silicon source

Article References: Ferdous, J., Rowe, R., Ning, K., Chen, Z.-H., Tissue, D. T., & Johnson, S. N. (2026). Silicon-mediated alleviation of salinity stress in wheat is linked to reduced sodium accumulation but depends on cultivar and silicon source. Plant and Soil. https://doi.org/10.1007/s11104-026-09104-3

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09104-3

Keywords: wheat, silicon, salinity stress, sodium accumulation, plant physiology, abiotic stress, soil science, crop resilience, amorphous silica, potassium silicate, cultivar variation, ion homeostasis