Bioimaging techniques trace foliar phosphate uptake pathways and visualize whole-leaf photosynthetic restoration processes in phosphorus-deficient barley.

Foliar fertilization delivers essential nutrients directly to plant tissues, reducing excessive soil fertilizer applications that can lead to eutrophication following nutrient leaching. Foliar nutrient absorption is a dynamic process affected by leaf surface structure and composition, plant nutrient status, and ion physicochemical properties. We applied multiple methods to study the foliar absorption behaviors of manganese (Mn) and phosphorus (P) in nutrient‐deficient spring barley (Hordeum vulgare) at two growth stages. Nutrient‐specific chlorophyll a fluorescence assays were used to visualize leaf nutrient status, while laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) was used to visualize foliar absorption pathways for P and Mn ions. Rapid Mn absorption was facilitated by a relatively thin cuticle with a low abundance of waxes and a higher stomatal density in Mn‐deficient plants. Following absorption, Mn accumulated in epidermal cells and in the photosynthetically active mesophyll, enabling a fast (6 h) restoration of Mn‐dependent photosynthetic processes. Conversely, P‐deficient plants developed thicker cuticles and epidermal cell walls, which reduced the penetration of P across the leaf surface. Foliar‐applied P accumulated in trichomes and fiber cells above leaf veins without reaching the mesophyll and, as a consequence, no restoration of P‐dependent photosynthetic processes was observed. This study reveals new links between leaf surface morphology, foliar‐applied ion absorption pathways, and the restoration of affected physiological processes in nutrient‐deficient leaves. Understanding that ions may have different absorption pathways across the leaf surface is critical for the future development of efficient fertilization strategies for crops in nutrient‐limited soils.

The race to meet net zero targets by 2050, while rapidly transitioning to a circular economy (CE) within the next decade, is shaping strategic Australian sustainability policy. While the success of integrating CE concepts relies on coordinating system-wide change, policies and strategies are still evolving under the traditional silos of waste and energy management. This presents multiple barriers to critical sectors, such as agriculture, which aims to become an $AUD100 billion industry by 2030. Agri-food systems face the challenge to meet growing global food demand, expected to increase by 70% by 2050, while decreasing emissions, resource use and waste production. Agriculture plays essential push and pull roles in meeting net zero targets and in developing a truly CE. Bioenergy, a critical part of the renewable circular bioeconomy, sits at the intersection of net zero and CE by producing renewable energy and recovering bioresources from waste biomass. By integrating agricultural end-users as key stakeholders, bioenergy can shift from a waste-to-energy process to a multi-resource generating process. These policy areas could be integrated via a similar approach to the Australian National Agricultural Innovation Policy Statement, with the goal of supporting agricultural production, while reducing emissions and maximising renewable resource use efficiency.

Antimony is a priority environmental contaminant typically present as either the trivalent (Sb^III) or the pentavalent (Sb^V) oxidation state in aquatic systems. Both the toxicity and mobility of antimony are affected by its speciation, and thus the accurate measurement of antimony speciation is essential for investigating the behaviour of this contaminant in aquatic systems. Here we present a diffusive gradients in thin films (DGT) technique, which utilises a binding layer containing a thiol-based adsorbent (3-mercaptopropyl functionalised silica gel), for the selective measurement of Sb^III in surface waters and sediment porewaters. We also evaluated the Metsorb DGT technique, which has been previously reported to accurately measure Sb^V, for its ability to accumulate Sb^III and thus allow the measurement of total inorganic antimony. Both the mercapto-silica and Metsorb DGT techniques showed a high affinity for Sb^III, with uptake efficiencies >97%. Elution efficiencies of 86.9 ± 2.6% and 88.1 ± 1.2% were obtained for mercapto-silica and Metsorb, respectively, with 1 mol L⁻¹ H₂O₂ in 1 mol L⁻¹ NaOH. The accumulation of Sb^III by these DGT techniques was linear with time (R² > 0.99) and unaffected by pH (4.07–8.05), ionic strength (0.001–1.0 mol L⁻¹ NaCl), bicarbonate (1–15 mmol L⁻¹), and an artificial seawater matrix (pH 8.34; salinity 34.8). Finally, the mercapto-silica DGT technique was applied to measure porewater concentrations of Sb^III and As^III in a contaminated freshwater sediment at high resolution.