Analysis of plant and fruit growth and yield under a micro sap flow sensor automated irrigation in substrate hydroponics for tomato cultivation

The aim of this study is to compare irrigation efficiency between sap flow sensor-automated system (SF) and conventional irrigation system based on integrated solar radiation (ISR) in tomato rockwool hydroponics. While the total irrigation volume was higher, the drainage ratio was lower in the SF system, compared to the ISR system. Although fresh weights of leaf and stem were higher in the SF system, no significant difference in marketable fruit weight, water use efficiency (WUE), and irrigation volume consumed for producing 200 g of tomato between the two systems. The daily average of sap flow density (SFD) was very close to the change of solar irradiance (SI) in the plant grown under the SF system more than under the ISR system, that may be due to irrigation scheduling based on plant transpiration. Correlation coefficient (r²) between the sap flow measured water uptake and load cell measured water uptake was 0.68. Further studies should demonstrate that SF irrigation system is a convenient method for hydroponic farmers with advantages, such as growth, higher yield, WUE, and accuracy.