Browsing by Author "Read, TL"

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    Investigating the foliar uptake of zinc from conventional and nano-formulations: a methodological study
    (CSIRO Publishing, 2019-06-06) Read, TL; Doolette, CL; Cresswell, T; Howell, NR; Aughterson, RD; Karatchevtseva, I; Donner, E; Kopittke, PM; Schjoerring, JK; Lombi, E
    Zinc (Zn) deficiency affects half of the world’s arable soil and one-third of the world’s human population. Application of Zn foliar fertilisers to cereal crops can be an effective way to increase grain Zn content; however, commonly used formulations can scorch the leaf (e.g. soluble Zn salts) or are prohibitively expensive (e.g. chelated Zn, ZnEDTA). Zinc oxide nanoparticles (ZnO-NPs) may offer an efficient and cost-effective alternative, but little is known regarding the mechanisms of Zn uptake and translocation within the plant. Foliar-applied Zn is analytically challenging to detect, locate and quantify, as it is omnipresent. Furthermore, any single analytical technique does not have the detection limit or spatial resolution required. In this study, the uptake and mobility of foliar-applied ZnEDTA, ZnO-NPs and ZnO microparticles (ZnO-MPs) to wheat (Triticum aestivum L.) were investigated using inductively coupled plasma mass spectroscopy (ICP-MS), synchrotron-based X-ray fluorescence microscopy (XFM) and radiotracing techniques using 65Zn-labelled formulations. The three techniques were compared to highlight limitations and advantages of each. We also report, for the first time, a novel time-resolved in vivo autoradiography imaging technique that can be used to visualise 65Zn in live plants treated with foliar applications of 65ZnO-NPs and MPs. The images were supplemented by gamma spectroscopy analysis for quantification. The results of this study provide important insights into the analytical challenges faced when investigating foliar-applied Zn nanofertilisers in plants. Potential solutions using nuclear techniques are also discussed, which in turn may ultimately lead to the development of more efficient foliar fertilisers. © CSIRO 2019
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    Translocation of foliar absorbed Zn in sunflower (Helianthus annuus) leaves
    (Frontiers, 2022-03-02) Li, C; Wang, LL; Wu, J; Blamey, FPC; Wang, N; Chen, YL; Ye, Y; Wang, L; Paterson, DJ; Read, TL; Wang, P; Lombi, E; Wang, YH; Kopittke, PM
    Foliar zinc (Zn) fertilization is an important approach for overcoming crop Zn deficiency, yet little is known regarding the subsequent translocation of this foliar-applied Zn. Using synchrotron-based X-ray fluorescence microscopy (XFM) and transcriptome analysis, the present study examined the translocation of foliar absorbed Zn in sunflower (Helianthus annuus) leaves. Although bulk analyses showed that there had been minimal translocation of the absorbed Zn out of the leaf within 7 days, in situ analyses showed that the distribution of Zn in the leaf had changed with time. Specifically, when Zn was applied to the leaf for 0.5 h and then removed, Zn primarily accumulated within the upper and lower epidermal layers (when examined after 3 h), but when examined after 24 h, the Zn had moved to the vascular tissues. Transcriptome analyses identified a range of genes involved in stress response, cell wall reinforcement, and binding that were initially upregulated following foliar Zn application, whereas they were downregulated after 24 h. These observations suggest that foliar Zn application caused rapid stress to the leaf, with the initial Zn accumulation in the epidermis as a detoxification strategy, but once this stress decreased, Zn was then moved to the vascular tissues. Overall, this study has shown that despite foliar Zn application causing rapid stress to the leaf and that most of the Zn stayed within the leaf over 7 days, the distribution of Zn in the leaf had changed, with Zn mostly located in the vascular tissues 24 h after the Zn had been applied. Not only do the data presented herein provide new insight for improving the efficiency of foliar Zn fertilizers, but our approach of combining XFM with a transcriptome methodological system provides a novel approach for the study of element translocation in plants. © 2022 Li, Wang, Wu, Blamey, Wang, Chen, Ye, Wang, Paterson, Read, Wang, Lombi, Wang and Kopittke. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
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    Zinc accumulates in the nodes of wheat following the foliar application of 65Zn oxide nano- and microparticles
    (American Chemical Society, 2021-05-26) Read, TL; Doolette, CL; Howell, NR; Kopittke, PM; Cresswell, T; Lombi, E
    Using zinc (Zn) foliar fertilizers to enhance the grain quality of wheat (Triticum aestivum) can be an effective alternative or supplement to Zn soil fertilizers. However, knowledge about the mechanisms of Zn absorption and translocation following foliar application is scarce. Here, autoradiography and γ-spectrometry were used to investigate the behavior of 65Zn applied to wheat leaves as soluble 65Zn chloride (65ZnCl2), chelated 65Zn (65ZnEDTA), 65Zn oxide nanoparticle (65ZnO-NP) suspensions, and 65ZnO microparticle (65ZnO-MP) suspensions. The largest amount of 65Zn absorption occurred in 65ZnCl2 treated leaves. However, this treatment (65ZnCl2) also had the lowest proportion of absorbed 65Zn translocated away from the treated leaf after 15 d due to leaf scorching (p = 0.0007). Foliar-applied 65ZnO-NPs and 65ZnO-MPs had the lowest absorption, but 65ZnO-NPs had the highest relative translocation. 65Zinc EDTA was intermediate, with higher 65Zn absorption than 65ZnO treatments but similar translocation. Regardless, the majority of the foliar-applied 65Zn remained in the treated leaf for all treatments. Furthermore, 65ZnO-NPs and 65ZnO-MPs accumulated in plant nodes, suggesting that Zn was absorbed as dissolved 65Zn and particulate 65ZnO. Overall, the form and amount of absorbed 65Zn affected translocation. © 2021 American Chemical Society
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    Zinc from foliar-applied nanoparticle fertiliser is translocated to wheat grain: a 65Zn radiolabelled translocation study comparing conventional and novel foliar fertilisers
    (Elsevier, 2020-12-20) Doolette, CJ; Read, TL; Howell, NR; Cresswell, T; Lombi, E
    Foliar zinc (Zn) fertilisers can be used to supplement or replace soil applications of Zn in situations where soil properties may decrease the plant bioavailability of Zn. However, conventional foliar Zn formulations such as zinc sulfate can cause leaf damage due to the rapid release of high amounts of Zn2+ into leaf tissue which can be locally phytotoxic. Zinc oxide nanoparticles (ZnO-NPs) offer an alternative approach by providing a more sustained release of Zn into leaf tissue, and potentially avoiding the need for multiple applications. We compared the efficacy of ZnO-NPs and microparticles (ZnO-MPs) to that of conventional formulations (ZnCl2 and ZnEDTA) in wheat. This is the first study to use 65Zn radiolabelled formulations and gamma spectrometry to determine the translocation of Zn to the grains and subsequent efficiency of foliar-applied ZnO-NP fertilisers. We found that ZnEDTA was the most efficient fertiliser in terms of the proportion of applied Zn translocated to wheat grain. We also investigated the effect of Zn application rate on fertiliser efficiency. For all forms of Zn, when plants were treated with Zn at 750 mg/L or 75 mg/L, there were no significant differences in the concentration of applied Zn translocated to the grain. This suggests that current Zn application rates could be decreased while still maintaining the nutritional quality of grain. Finally, using photo-stimulated luminescence (PSL) autoradiography and synchrotron-based X-ray fluorescence microscopy (XFM) we showed that the grain distribution of foliar-applied Zn mirrors that of Zn derived from root uptake. Crown Copyright © 2020 Published by Elsevier B.V.