FePO4 NPs Are an Efficient Nutritional Source for Plants: Combination of Nano-Material Properties and Metabolic Responses to Nutritional Deficiencies.

Davide Sega,Anita Zamboni,Barbara Baldan,Zeno Varanini

doi:10.3389/fpls.2020.586470

Davide Sega, Anita Zamboni + Show 2 more

Open Access

https://doi.org/10.3389/fpls.2020.586470

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Abstract

Phosphorous and iron are a macro- and micronutrient, respectively, whose low bioavailability can negatively affect crop productivity. There is ample evidence that the use of conventional P and Fe fertilizers has several environmental and economical disadvantages, but even though great expectations surround nanotechnology and its applications in the field of plant nutrition, little is known about the mechanisms underlying the uptake and use of these sub-micron particles (nanoparticles, NPs) by crop species. This work shows that cucumber and maize plants both use the nutrients borne by FePO4 NPs more efficiently than those supplied as bulk. However, morpho-physiological parameters and nutrient content analyses reveal that while cucumber plants (a Strategy I species with regard to Fe acquisition) mainly use these NPs as a source of P, maize (a Strategy II species) uses them preferentially for Fe. TEM analyses of cucumber root specimens revealed no cell internalization of the NPs. On the other hand, electron-dense nanometric structures were evident in proximity of the root epidermal cell walls of the NP-treated plants, which after ESEM/EDAX analyses can be reasonably identified as iron-oxyhydroxide. It appears that the nutritional interaction between roots and NPs is strongly influenced by species-specific metabolic responses.

Highlights

Phosphorous (P) and iron (Fe) are a macro- and micronutrient, respectively, whose low bioavailability can seriously limit crop productivity (Barber, 1995)
In order to test the effectiveness of FePO4 NPs (NPs) as a source of P and Fe for plant nutrition, we performed experiments on two hydroponically-grown crop species with different response strategies to Fe shortage: cucumber (Strategy I) and maize (Strategy II)
The ability of NPs to provide P and Fe was evaluated at the end of the growth period (14 and 17 days for cucumber and maize plants, respectively) by determining leaf SPAD index, shoot and root dry weight, and shoot/root ratio (Figures 1, 2, Supplementary Figures S2–S4)

Summary

Introduction

Phosphorous (P) and iron (Fe) are a macro- and micronutrient, respectively, whose low bioavailability can seriously limit crop productivity (Barber, 1995). It has been calculated that agriculture is responsible for 10% of all greenhouse gas emissions (EPA, 2017), it is essential to reduce its impact on the environment Nanotechnology in this respect is extremely promising, and could be the key to more sustainable practices Nanofertilizers are classified into four groups: macronutrient nanofertilizers, micronutrient nanofertilizers, nanomaterial-enhanced fertilizers, and plant growth stimulating nanomaterials (Liu and Lal, 2016) Thanks to their high surface area to volume ratio, these compounds would appear to be more effective than conventional fertilizers in increasing NUE and reducing the amount of elements applied and released into the environment (Marchiol et al, 2020)

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