A New Transpiration-Embolism Curve Model Based on Ultrasonic Acoustic Emissions

Ultrasoinc acoustic emissions (UAEs) can be used as index of plant water deficit. In order to avoid background noise interference, the UAEs detecting frequency is more than 100 KHz. The relationships between the conduits embolism and transpiration can describe the mathematical relationship of embolism degree and the plant physiologies, namely transpiration-embolism curve (TEC). The plant physiological activities are closely related with body water reserving from 8:00 to 14:00 when it is sunny, light adequate. The UAEs grow rapidly from 9:00 to 11:00, the concave and convex characteristics of Logistic curve are not obvious, the same to inflection point. In general, the maximum of transpiration rate occurs from 9:00 to 11:00, while the UAEs reach the maximum 1h later. Before irrigation, the plant is in the serious water stress conditions, and the soil water content is low, the UAEs are below 50 times before 7:00 and after 18:00, and long duration. After irrigation, the UAEs do not appear the peak, and the UAEs will decrease or disappear, while UAEs appear a small peak 1h or 2h later, the physiological activities will lag a short time, the length of time has the strong relationship with the water stress and embolism degree. Studies have shown that the embolism is sensitive to soil water content conditions, in other words, the potted plant shows the sensitivity of transpiration, and high soil water content can improve the plant embolism vulnerability.