Classic micronutrients and chelates have long been the standard in foliar feeding, but their effectiveness is limited by a physical barrier – particle size and the speed of absorption through the leaf cuticle. The nanotechnological approach to biostimulants – nano-silicon (nSi) and nano-chelates of trace elements – solves this very problem due to the radically smaller particle size and larger specific surface area. For agronomists and technologists, this is not a question of abstract science, but of a concrete choice: does the difference in efficiency justify the difference in price.
Nano-biostimulants are preparations based on nanoparticles with a size of 1–100 nm, which, due to their small size, penetrate the cuticle and cell walls of plants more easily than traditional compounds. This group includes nano-silicon (nSi, nano-SiO₂), nano-chelates of iron, zinc, manganese and molybdenum, as well as certain nanoforms of copper and selenium.
The main difference from conventional microfertilizers and chelates is not the chemical composition of the active ingredient, but the physical form of its delivery. The smaller particle size provides a larger contact area with the plant surface and more efficient transport of the active ingredient through the phloem and apoplast.
Silicon has long been considered a conditionally essential element that strengthens cell walls. Studies of the nanoform reveal a broader mechanism of action. Nanosilicon increases the activity of antioxidant enzymes – superoxide dismutase, catalase and ascorbate peroxidase, which neutralize reactive oxygen species that accumulate during stress.
Under salt stress, nanosilica helps regulate the Na⁺/K⁺ balance in cells, reducing the toxic load of sodium. In studies on soybeans, treatment with nanosilica in soil reduced the Na⁺/K⁺ ratio by approximately 40% and reduced the accumulation of proline, a marker of osmotic stress, by approximately 35% compared to the control. Nanosilica also participates in the regulation of gibberellins and jasmonic acid, which helps the plant maintain membrane integrity during drought.
A separate area of application is reducing the toxicity of heavy metals. In rice, nanosilicon reduces the accumulation of cadmium by inhibiting the transport genes responsible for the absorption of this metal by the roots.
Nano-chelates of iron, zinc and manganese are used mainly for foliar feeding. According to comparative studies, nanoforms of micronutrients increase the efficiency of absorption by about 18% compared to conventional forms, while for macronutrients the difference reaches about 29%.
The practical effect of nano-chelates is recorded in several directions:
In field studies on rice, nanochelated iron was used for grain biofortification, and treatment of stone crops with nanochelated iron increased the iron and calcium content in fruits and the proportion of soluble sugars. In Ukraine, studies on the partial replacement of NPK with nanochelates of trace elements were conducted, in particular, at the National University of Bioresources and Environmental Management using the example of wheat.
Despite the promise, the field of nano-biostimulants remains young: most products entered the market due to empirical success rather than due to a deep understanding of the mechanisms of interaction of nanoparticles with plant physiology.
Questions remain open regarding optimal doses for specific crops, long-term effects on soil microbiota, and standardization of methods for producing nanoparticles with reproducible properties batch-to-batch.
How is nano-silicon different from conventional silicon fertilizers?
Can nano-chelates be combined with traditional fertilizers?
How much more expensive are nano-biostimulants than traditional counterparts?
Are nanoparticles safe for soil and the environment?
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