In Planta Detection of Phosphate Uptake in Chrysanthemum Using a Miniaturized Electrochemical Microprobe Array

Phosphorus is an essential macronutrient governing key physiological traits in chrysanthemum. However, phosphate nutrition is typically evaluated based on fertilizer input rather than direct in planta uptake, limiting management accuracy. Here, we develop a miniaturized electrochemical microprobe array for direct in planta detection of phosphate in chrysanthemum stem sap. The array integrates a cobalt-based working electrode fabricated via an electroplating-then-etching technique and a titanium-based iridium dioxide reference electrode, all optimized for miniaturization and biocompatibility. The array demonstrated a wide linear detection range (10−5 to 10−1mol/L), good sensitivity (41 mV/dec), and strong anti-interference performance in the presence of coexisting ions. Biocompatibility tests confirmed minimal disruption to plant growth after short- and long-term probe implantation. In planta measurements revealed spatial variation in phosphate distribution along the stem and dynamic uptake responses following fertilizer application. These findings highlight the potential of this microprobe array for precise nutrient uptake analysis and sustainable phosphorus management in horticultural systems.