Benefits of sensors in tomato cultivation

The tomato (Solanum lycopersicum L.) is one of the high-value crops in the global market, mainly cultivated under irrigation. Tomato yield is often hampered due to unfavorable conditions, including climate, soil, and water availability. Sensor technologies have been developed and installed across the world to help farmers assess growing conditions, such as water and nutrient availability, soil pH, temperature, and topology.

The demand for tomatoes is high for both fresh consumption and industrial (processing) markets. Low production of tomatoes has been observed in many agricultural sectors, such as Indonesia, where mainly traditional farming systems are followed. Implementing technologies, such as Internet of Things (IoT) based applications and sensors, have substantially improved the yield of various crops, including tomatoes.

Sensors used to determine plant water content are based on multiple tools and techniques that include electrical impedance spectroscopy, near-infrared (NIR) spectroscopy, ultrasonic techniques, and leaf patch clamps. Soil moisture sensors and electrical conductivity sensors are used to detect soil structures, salinity, and conductivity. Some of the plant sensors used to improve tomato farming are discussed below.

Professor Jim Haseloff and his team at the University of Cambridge have recently developed a low-cost electrochemical sensor to monitor pH in xylem sap. This sensor was developed using ruthenium oxide nanoparticles due to its superior chemical stability, biocompatibility, and its ability to selectively react with hydrogen ions.

The sensor film is 80 nm thick, and its roughness is below 3 nm. This sensor can be directly implanted into the xylem of a tomato plant. The initial design of the sensor was improved, i.e., the noise was significantly reduced by using a cellulose-based coating on the electrodes.

Additionally, a heating system was incorporated to ensure homogeneity. The final design enabled the deposition of nanometrically thin films (sensors) into the xylem that can detect a range of analytes in a cost-effective manner.