Research & Application Of Water Stress Monitoring System Based On Acoustic Emission Technique For Crops

To avoid drought, which is always the main natural disaster of agricultural production, and improve the yield of crops, irrigation is the basic method. For a long time, how to detect water stress levels in crops accurately and apply a real-time accurate irrigation, is a popular topic for many researchers. As a result of researches, several water indexes were brought up from different methods, such as soil moisture content and air relative humidity, which were most commonly used in the past irrigation control system. For crop water stress, however, those are all insensitive and indirect indexes that represent the environmental states of crops. In SPAC, it is the plant that should be optimum indicator for irrigation control, because the soil factor and air factor, which control the balance of water in crops, can but be integrated by plant. As result, a new method is presented by using the acoustic emission (AE) signal from stem of individual plant as its demand information. Based on virtual instruments technique, which is becoming a popular tool in measurement and automation fields international, a computer-based detecting system is developed for the fast, real-time measurement. Take tomato crops for testing example in greenhouse, the relation between AE and transpiration, environmental factors has been studied. It has shown that a good agreement between acoustic emission and transpiration, and the AE signal is a good water stress index for irrigation control. So, a real-time irrigation control system based on plant physiological water needing information was established, and the effect experiment of irrigation control was made. Compared with timing irrigation, 34.02 percent water can be saved by using acoustic emission technique for irrigation control and the growing state of tomato crops doesn't be affected. The system works safely, operates easily and measures accurately, it is suitable to the need of scientific production and auto-manage of modern agriculture. A new research method for the physiological and ecological research of plant is applied by the system as well. In a word, it has great practical value and wide future of application.