Nondestructive Detection of Water Stress in Tomato Plants by Microwave Sensing.

概要

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Environmental stress can induce changes in physiological and physical conditions of a plant, and these changes influence the dielectric properties of the plant, which can be detected by measuring microwave transmission characteristics (scattering"S"parameter, S21) through the plant and its surrounding space. Therefore, experiments were conducted with tomato plants to examine the potential of using measurements of microwave transmission characteristics for real-time and non-contact monitoring of changes in plants caused by environmental stress. Tomato plants were subjected to water stress in the following environment : 12 h d-1 light period, 26°C/ 19°C (light/dark periods), and 200±10μmol m-2 s-1 PPF at the height of leaves used for measurements of stomatal conductance and photosynthetic rate. Time course changes in the microwave transmission parameter S21 were measured for a tomato plant during water stress, as well as changes in stomatal conductance and photosynthetic rate, which reflect the physiological condition of the plants. S21 parameter measurements were taken over the 1 000 to 3 000 MHz frequency range. Results showed that low frequencies near 1200 MHz were effective for detecting mild levels of water stress while frequencies above 2 400 MHz were effective for detecting moderate to severe levels of water stress.
日本生物環境工学会の論文