X-ray fluorescence spectroscopy presents a unique capability to probe the elemental content of plants in vivo, besides combination with other non-destructive tools to assess physiological processes.

In this study, we characterized Zn seed coats adhered on soybean seed surface [Glycine max (L.) Merrill] and then investigated the effects of such coatings on germination and finally monitored the transference of Zn from the coatings to the seedlings. For that, seeds were coated with ZnSO 4 , 40 nm ZnO, and 5 µm ZnO at 4 mg of Zn per kg of seed. The shape and homogeneity of Zn deposits on the seed surface depended on the type of Zn source. X-ray spectroscopy unraveled that before the germination, Zn neither crossed the seed coat nor was biotransformed. Regardless of the particle size, ZnO-based treatments increased germination ratio, seedlings root, and shoot development, whereas ZnSO 4 suppressed them. After sowing, most of Zn on the seed coat was transferred to soil, while less than 13 wt% was assimilated by the seedling 14 days after sowing. Either this minor fraction of Zn was taken up during the imbibition process or absorbed by during seedling growth. Zinc oxide-based treatments represent a viable alternative to Zn supply in order to boost soybean germination and seedling development.

The production and use of nanoparticles (NPs) in different fields increased in the last years. However, some NPs have toxicological properties, making these materials potential emerging pollutants. Therefore, it is important to investigate the uptake, transformation, translocation, and deposition of NPs in plants. In this work, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and micro X-ray fluorescence (μ-XRF) were used to investigate the uptake and translocation of La2O3 NPs to stem and leaves of Pfaffia glomerata (Spreng.) Pedersen after in vitro cultivation of plants in the presence of 400 mg L–1 of La2O3 NPs. By using LA-ICP-MS and μ-XRF, image of the spatial distribution of La in the leaves was obtained, where higher concentration of La was observed in the main veins. Differences in the signal profile of La in leaves of plants cultivated in the presence of bulk La2O3 (b-La2O3) and La2O3 NPs were observed. Sharp peaks of La indicated that NPs were transported to the stems and leaves of plants treated with La2O3 NPs. Both LA-ICP-MS and μ-XRF techniques have shown to be useful for detecting NPs in plants, but LA-ICP-MS is more sensitive than μ-XRF and allowed better detection and visualization of La distribution in the whole leaf.

Agriculture is responsible for supplying food, feed, fibres, and an increasing fraction of fuel and raw chemicals for industry. Fulfilling such demands sustainably is one of the major challenges of...