Effects of acoustic vibration on Olea europaea cv “Leccino”

Acoustic vibrations can trigger various plant morphological, physiological, and genetic responses. Although it is still difficult to understand how plants can perceive and communicate through these vibrations, the study of the application of mechanical vibration treatments in agriculture has attracted increasing interest in recent years. Plants have been proven to emit low-intensity, high-pitched sounds, such as cavitation, that occur under water-deficient conditions (De Roo et al., 2016; Jin-Soo Son et al., 2024), but there may be others. Many studies suggest the capacity of plants to perceive certain airborne sounds, including those of high intensity. Moreover, many studies report the sensibility of plants to substrate vibrations, such as leaf vibrations generated by the chewing of insects or the underground passage of running water (Gagliano et al., 2012; Appel & Cocroft, 2014; Kollasch et al., 2020; Yin et al., 2020). In this work, we conducted experimental tests to investigate treatment effects with low-frequency (120 Hz) acoustic vibrations on Olea europea L. cv. ‘Leccino’ over 6 months. Changes were observed in the morphology and architecture of the plant, gas exchange and leaf structures. Plants subjected to vibration showed a smaller leaf area of newly produced leaves and lower levels of photosynthetic activity and stomatal conductance than in the control group. It was also possible to observe different leaf structures using a confocal microscope. The vibrating plants showed a thickening of the upper and lower cuticles at the leaf level, a distortion of the cells composing the palisade layer and a decrease in chlorophyll levels within the mesophyll compared to the control group. These results demonstrate the ability of plants to adapt to specific stress conditions and the need for further studies to understand the reason for these changes at the structural level. Furthermore, further studies are needed to understand whether these changes at the leaf level can influence plant resistance to abiotic and biotic stresses. Adopting preventive control strategies such as this can positively influence the development of more sustainable agricultural practices by avoiding using chemicals and external inputs. Although the mechanisms underlying plants' perception of these mechanical vibration treatments are not yet fully understood, they may contribute to spreading more ecological and environmentally friendly agricultural practices (Choi et al., 2017; Jin-Soo Son et al., 2024).