Species-dependent designed ultrasonic acoustic emissions of tomato and tobacco under drought and mechanical injury: a plant-level cross-species analysis with an exploratory visualisation framework

Abstract

Ultrasonic emissions offer a non-destructive route for detecting plant stress, but their transferability across species remains uncertain. A secondary analysis of 5,477 recordings from tomato and tobacco was conducted using 3,063 plant-emission events grouped into 170 plant-condition units representing drought and mechanical injury. Twenty-two temporal, amplitude and spectral descriptors were extracted and aggregated at plant level to prevent repeated emissions from the same plant entering both training and testing sets. Significant species × treatment interactions occurred for peak amplitude, root mean square amplitude and signal energy. Within-species classification achieved balanced accuracies of 0.747 for tomato and 0.706 for tobacco, whereas strict transfer was near chance from tomato to tobacco (0.518) and tobacco to tomato (0.484). Permutation analysis identified amplitude, dominant frequency, bandwidth and ultrasonic band energy as influential variables. The findings demonstrate measurable but strongly species-dependent acoustic stress signatures.

Bangladesh J. Bot. 55(3): 587-595, 2026 (September)