Wearable Plant Electronics Enables Early Detection of Salt Stress by Tracking K ⁺ /Na ⁺ Homeostasis and Salicylic Acid Accumulation

Soil salinization threatens global food security by disrupting plant ion homeostasis and triggering complex hormonal signaling cascades. Early detection of salt stress and real-time tracking of stress-responsive physiological dynamics remain major technical bottlenecks, as current methods rely on destructive sampling or single-parameter sensing that obscure the crosstalk between ionic and hormonal networks. Here, we report a wearable plant electronic system that enables noninvasive, in situ monitoring of K + /Na + homeostasis and salicylic acid (SA) accumulation, two key indicators of plant salt stress adaptation. The integrated platform combines flexible laser-induced graphene (LIG) ion-selective electrodes enhanced with a SnS 2 –MoS 2 heterostructure for stable potentiometric sensing, a reverse iontophoresis module for noninvasive analyte extraction, and a biocompatible flexible zinc-air battery for long-term power supply. Deployed on tobacco plants, the wearable device detected salt stress within 24 h by capturing the initial disruption of the K + /Na + ratio and the subsequent accumulation of SA, far preceding visible symptoms. The temporally resolved data revealed a dynamic correlation where SA accumulation coincided with a partial recovery of the K + /Na + ratio, suggesting an active role of SA in modulating ion homeostasis. This wearable plant electronic system transcends the limitations of conventional single-parameter detection, providing a powerful tool for early stress diagnosis, deciphering plant adaptive mechanisms, and advancing precision agriculture to mitigate the impact of soil salinization.