A multifunctional nanophotonic fertilizer enhances crop growth by converting near-infrared light into red light, releasing magnesium and manganese in response to pH, and enabling in-plant nutrient tracking.
(Nanowerk Spotlight) Fertilizers are among the most widely used tools in agriculture, yet much of what they deliver never reaches the crops they’re intended to support. Magnesium, nitrogen, manganese, and other essential nutrients are applied to soil at large scale, but a significant portion is lost through runoff, chemical reactions, or evaporation before plants can absorb it. The consequences extend beyond yield loss. Nutrient runoff contributes to environmental degradation, while poor uptake efficiency raises input costs and complicates efforts to manage soil health.
What limits current fertilizer strategies isn’t a lack of nutrients but a lack of control. Plants take in nutrients through roots and leaves, but this process is highly sensitive to timing, chemical form, and environmental conditions. Traditional fertilizers rely on indirect delivery. They dissolve into soil, disperse through water, and interact with surrounding minerals before possibly reaching plant cells. In acidic soils or areas with high rainfall, key nutrients like magnesium and manganese often leach away or become locked in unavailable forms.
These inefficiencies affect more than plant metabolism. Magnesium plays a central role in the formation of chlorophyll, directly influencing a plant’s ability to absorb sunlight. Manganese contributes to water splitting in photosynthesis and supports antioxidant defenses during stress. Both are critical to plant function, but standard delivery methods remain poorly suited to ensuring their availability at the cellular level.
This gap between what plants need and what conventional methods can deliver has motivated researchers to look for new approaches. Advances in nanomaterials have made it possible to design fertilizers that interact more precisely with plant systems, entering tissues directly, releasing nutrients in response to local chemical conditions, and assisting with light absorption. Some of these materials can be tracked in real time as they move through a plant’s internal structures, opening the way for a new kind of responsive, data-informed agriculture.
A study recently published in Advanced Functional Materials (“Near-Infrared Nano-Photofertilizer with Red Emission and Micronutrient Release Co-Enhanced Crop Growth”) introduces one such system, described by the authors as a nanophotofertilizer. Developed by researchers at Northeast Forestry University, it combines nutrient delivery, light conversion, and in-plant monitoring in a single nanotechnology platform designed to interact directly with plant physiology.
Schematic diagram showing the preparation of nanocomposites a) and enhanced photosynthetic activity through NIR laser irradiation, boosting photo-response and release of metal ions b). (Image: Reprinted with permission by Wiley-VCH Verlag) (click on image to enlarge)
The material, referred to as L@MgMn, is engineered to release magnesium and manganese inside plant cells, emit red light to enhance photosynthesis, and provide near-infrared signals that allow its movement to be visualized. Rather than acting as a passive supplement, it is designed to function as an active component in plant metabolism.
The core of the material is a lanthanide-doped nanoparticle that absorbs near-infrared light at 980 nanometers and re-emits it as red light around 650 nanometers, a range well suited for absorption by chlorophyll. This process, known as upconversion, makes use of solar wavelengths that would otherwise pass through the plant unused. Surrounding the core is a silica shell that contains magnesium and manganese ions. These ions are not released all at once but respond to the mildly acidic environment found inside plant tissues, allowing for a controlled and localized delivery.
In tests using Nicotiana benthamiana, a model species in plant research, the L@MgMn particles were applied as a foliar spray. They entered leaves through natural pores called stomata and were then tracked inside the plant using their infrared emission. Imaging showed that the particles traveled from leaves to stems and roots through the plant’s internal transport system, confirming systemic uptake. These particles also remained stable inside the plant, with no detectable release of rare earth metals from the nanoparticle core.
The physiological results were clear. At a concentration of 100 micrograms per milliliter, plants treated with L@MgMn showed a 24.4 percent increase in chlorophyll a and a 31.7 percent increase in chlorophyll b. Total chlorophyll content rose by 26.8 percent compared to untreated controls. These changes coincided with higher rates of photosynthesis, as measured by gas exchange. Net photosynthetic rate increased by 16.6 percent, while stomatal conductance, transpiration rate, and internal carbon dioxide concentration also rose.
The material improved not just light harvesting but also biochemical performance. Activity of RuBisCO, the enzyme responsible for carbon fixation in the Calvin cycle, increased by 46.6 percent at the optimal concentration. This indicates that improvements in photosynthetic pigment levels translated into higher rates of carbon assimilation.
L@MgMn also helped protect plants from oxidative stress. Manganese ions within the shell supported redox reactions that neutralize reactive oxygen species, including superoxide and hydrogen peroxide. In vitro tests showed that the material could decompose hydrogen peroxide and catalyze the production of hydroxyl radicals, which can further reduce oxidative molecules. In plant tissues, NBT staining confirmed that treated leaves had lower levels of reactive oxygen buildup compared to untreated ones.
To evaluate how nutrients were released, the researchers tested the material in mildly acidic conditions designed to mimic the plant environment. In the presence of glutathione, a compound found inside cells, magnesium and manganese ions were released from the silica shell in a sustained manner over 12 hours. This release pattern matched the timing of key metabolic processes and helped avoid the waste associated with bulk fertilizer application.
The surface properties of the particles also contributed to their effectiveness. L@MgMn had a moderate positive surface charge, which promoted adhesion to the negatively charged surfaces of plant cells. Contact angle measurements showed that the material spread more evenly on leaves than water or undoped silica particles. This increased surface contact improved retention and uptake following foliar application.
However, the concentration of the material proved critical. While 100 micrograms per milliliter improved growth and photosynthesis, higher concentrations led to diminished performance and signs of stress. This highlights the need for careful optimization in field applications and suggests a narrow effective dosage range.
What distinguishes this material is not any single property but the combination of features in one design. It delivers magnesium and manganese where they are needed, enhances the efficiency of light absorption, reduces oxidative stress, and can be tracked inside the plant. These functions work in parallel rather than in isolation, offering a coordinated response to multiple challenges in crop production.
The use of silicon as the structural base makes the material relatively scalable, and the synthesis method is compatible with doping strategies for other nutrient ions. While this study focused on controlled laboratory conditions, the results point toward potential applications in precision agriculture, especially where nutrient availability and environmental conditions fluctuate.
This study offers an example of how nanomaterials can be engineered to work with, rather than around, the complexity of plant biology. Instead of treating fertilization, light capture, and stress resistance as separate problems, this material addresses all three through a single, targeted platform.
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