Basic Study on Estimating Water Stress of a Plant Using Vibration Measurement of Leaf

Abstract

A new noninvasive method for estimating the water stress of a plant was proposed. In order to investigate this method, we first examined the characteristic frequency of an individual leaf picked from the plant, and obtained the result that its characteristic frequency decreased in proportion to the reduction in the water content of the leaf. Next, we applied this method to a leaf on a branch and confirmed the same tendency when the water stress was increased by stopping the water supply of a plant cultured in water. From these results, it was suggested that the water stress of the plant could be estimated from the vibration measurement of the leaf. Lastly, the relationship between the water potential of the leaf and its elastic constant was discussed with the soil-plant-atmosphere-continuum model (SPAC model), and Young's modulus of a tomato leaf was roughly estimated.

Effects of hydric stress on vibrational frequency patterns of Capsicum annuum plants

“…For instance, studies performed in trees have shown that their vibrational response partially depends on their natural frequency damping ratio. In addition, the results of this study show that the samples with HHS have a higher natural frequency that is ̴ 2.55 to̴ 7.87 times higher, exhibiting an opposite effect to research by Sano et al (2013). 8 The authors mention the inverse behavior of this phenomenon in the vibration of leaves.…”

“…), as well as organs such as leaves and trichomes. 8,10,35 Then, it is possible to say that environmental variations cause plants to adapt their structure in order to face hostile conditions. The underlying response integrates mechanical inputs requiring immediate modifications that will, therefore, adjust the first natural frequency of vibration and other vibrations from the whole plant system.…”

“…For example, the predominant peak response of the natural frequency of a tomato (Lycopersicon esculentum) plant's leaf was 5 Hz, which was calculated by applying an excitation force to the stem and using a laser vibrometer. 8,9 To measure vibration signals in alive tissue like plants correctly, it is necessary to have adequate sensors with high sensitivity and instruments that are able to measure very small displacements, such as laser doppler vibrometers. [8][9][10] For instance, a laser doppler (Polytec PSV-3D -B&K) has a wide bandwidth from 0 to 100 kHz, a frequency resolution of 2 Hz, and the ability to measure displacements in the order of femtometers.…”

“…8,9 To measure vibration signals in alive tissue like plants correctly, it is necessary to have adequate sensors with high sensitivity and instruments that are able to measure very small displacements, such as laser doppler vibrometers. [8][9][10] For instance, a laser doppler (Polytec PSV-3D -B&K) has a wide bandwidth from 0 to 100 kHz, a frequency resolution of 2 Hz, and the ability to measure displacements in the order of femtometers. In this regard, the understanding of how plants vibrate could represent additional cues to integrate the physiological, biochemical, and molecular responses linked to biomechanics that still need to be researched.…”

Estimation of water stress of plant by vibration measurement of leaf using acoustic radiation force

“…In order to develop a more sensitive detection technique for water stress of the plant, we have focused on the stiffness of the leaf, which is related to wilting, and confirmed that the natural frequency of a leaf decreases with the reduction of water content in the leaf [13]. In addition, Young's modulus was estimated and compared with the reported value [14].…”