Advances in electrochemical sensors for smart farming and precision agriculture: a focus on phytohormone quantification.

Electrochemical sensors detect target molecules using biorecognition elements, such as antibodies or molecularly imprinted polymers (MIPs), or the target's inherent electrocatalytic activity, with a transducer converting the resulting interaction into a measurable electrical signal. In agriculture, they are gaining importance for optimizing plant growth, crop quality, safety, and overall productivity. Healthy plants are vital globally as they ensure food security, support ecosystems, produce oxygen, protect soil, and sustain human life and environmental balance worldwide. Phytohormones are naturally occurring signaling molecules produced by plants that regulate growth, defense, responses to environmental stimuli and adaptation processes. Hence, fluctuations in phytohormone levels serve as early biochemical indicators of stress, often before visible signs appear. Major phytohormones involved in stress responses include abscisic acid (ABA), ethylene, methyl jasmonate (MeJA), salicylic acid (SA), indole-3-acetic acid (IAA), and cytokinins (CKs). Quantifying these phytohormones provides the early detection of abiotic and biotic stresses such as drought, nutrient imbalance, salinity, and pathogen attack. This early diagnosis supports timely intervention, improves crop management, and enhances agricultural productivity. Electrochemical sensors allow for rapid, sensitive, and sometimes real-time detection, even in field conditions. Their portability and compatibility with digital technologies make them promising tools for precision agriculture. However, challenges remain, such as ensuring durability in harsh environments, reducing device costs, and enabling detection of multiple targets simultaneously. Overall, electrochemical biosensors represent a powerful innovation in modern agriculture. With continued development and integration into smart farming systems, they are expected to play a crucial role in sustainable and efficient agricultural practices.