Iron Nanoparticles Help Almond Trees Cope with Soil Stress

David Palenski
15th February, 2024

Iron Nanoparticles Help Almond Trees Cope with Soil Stress

Almond (Prunus amygdalus)

Photo adapted from: Franck Cabot / CC BY (Source)
Iron is a vital nutrient for plant health, playing a key role in photosynthesis – the process plants use to convert light into energy[2]. However, in many agricultural soils, iron isn’t readily available to plants, even if it’s present. A common issue, particularly in orchards, is high bicarbonate concentration in the soil. Bicarbonate, a form of carbon, can interfere with a plant’s ability to absorb iron, leading to iron deficiency. This is a significant problem as it limits growth and reduces crop yields. Researchers at the University of Tehran recently investigated whether specially formulated iron nanoparticles could help almond trees overcome this issue[1]. The study focused on almond trees grown without soil (soilless culture) to precisely control the growing conditions. The researchers created bicarbonate stress by adding sodium bicarbonate and calcium carbonate to the nutrient solution the trees were irrigated with. They tested three levels of bicarbonate concentration: none, a low level, and a high level. Alongside these different bicarbonate treatments, they applied different sources of iron: a standard commercial iron fertilizer (FeEDDHA) and four types of iron nanoparticles (Fe–NCs). These nanoparticles were created using extracts from the husks of almond, pistachio, walnut, and pomegranate – essentially using waste products from these fruits to create a potential solution. The results showed that high bicarbonate levels caused typical signs of iron deficiency: leaves turned pale (chlorophyll decline), developed dead areas (necrosis), and the trees grew less (decreased leaf area). These visible symptoms were linked to a decrease in iron concentration within the leaves and evidence of cellular damage caused by oxidative stress – an imbalance in the plant’s internal chemistry. Oxidative stress was measured by looking at hydrogen peroxide levels (an indicator of damage) and the stability of cell membranes. Interestingly, not all the iron nanoparticles performed equally well. While nanoparticles made from walnut and pistachio actually worsened the effects of bicarbonate stress, those made from almond and pomegranate were surprisingly effective. These almond and pomegranate nanoparticles were able to restore chlorophyll levels, reduce oxidative damage, and increase iron concentration in the leaves to levels comparable to those achieved with the standard commercial fertilizer. This improvement was linked to increased protein levels, better detoxification of hydrogen peroxide, and increased activity of an enzyme called catalase, which helps break down harmful peroxides. This study builds on previous research showing that the availability of iron in soil is heavily influenced by pH levels[3]. Specifically, as pH increases (becoming more alkaline, like with bicarbonate), iron can form insoluble compounds that plants can’t absorb. The formation of iron (oxy)hydroxide nanoparticles at higher pH, as observed in other studies[3], highlights the complex chemical changes occurring in the soil. The research also aligns with findings that bicarbonate stress can disrupt iron uptake and transport within plants, differing from the effects of direct iron deficiency[4]. The current study suggests that the almond and pomegranate nanoparticles may be overcoming this issue by providing iron in a form that is more easily absorbed even in the presence of bicarbonate. The success of the almond and pomegranate nanoparticles is particularly promising because they are created from readily available, low-cost materials. This offers a potentially sustainable and affordable solution for farmers struggling with bicarbonate-induced iron deficiency, particularly in regions where this is a common problem.

AgricultureBiotechPlant Science

References

Main Study

1) Differential responses of green-synthesized iron nano-complexes in mitigating bicarbonate stress in almond trees.

Published 15th February, 2024

https://doi.org/10.1016/j.heliyon.2024.e25322

Related Studies

2) Iron nutrition, biomass production, and plant product quality.

https://doi.org/10.1016/j.tplants.2014.07.005

3) The influence of pH on iron speciation in podzol extracts: iron complexes with natural organic matter, and iron mineral nanoparticles.

https://doi.org/10.1016/j.scitotenv.2013.04.076

4) Direct and Bicarbonate-Induced Iron Deficiency Differently Affect Iron Translocation in Kiwifruit Roots.

https://doi.org/10.3390/plants9111578


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