Remote Field Crop Water Stress Monitor

Abstract. Ongoing drought and ever increasing urban demand for water have put tremendous pressure on growers to use water resources wisely. Past research at UC Davis and elsewhere has shown that irrigation management based on plant water status can improve crop quality and water use efficiency. The objective of this project was to adapt an existing perennial crop water stress monitor for use in annual field crops, such as processing tomatoes, to assist in irrigation management. A thermal infrared sensor attached to an adjustable mount overlooked a processing tomato field and measured the temperature of a circular viewing area, consisting of a combination of canopy and soil. Moreover, a digital camera in conjunction with image processing software estimated the total canopy area viewed by the sensor and assisted in determining the average leaf temperature. Furthermore, the system was integrated with a suite of other sensors that measured microclimatic variables, such as wind speed, air temperature, relative humidity, and incident radiation that also affect the plant water status. The system also included a cellular modem to upload the data to the internet in real-time. Moreover, weather resistant housing made the system ready for harsh environmental conditions in the field. The system was tested in an irrigated processing tomato field and was found to function satisfactorily. This field-ready data acquisition system has potential for providing useful information to farmers in implementing precision irrigation in field crops.