Research Papers Related to Hydroponic Systems

• Rosa-Rodríguez, R. D. L., Lara-Herrera, A., Trejo-Téllez, L. I., Padilla-Bernal, L. E., Solis-Sánchez, L. O., & Ortiz-Rodríguez, J. M. (2020). Water and fertilizers use efficiency in two hydroponic systems for tomato production. Horticultura Brasileira, 38(1), 47-52.
  
  The authors set out to compare open and closed (actually semi-closed as used in this study) hydroponic systems based on the efficiency of water and fertilizer use, as well as yield. They found no differences in yield between systems but that the closed system had significantly greater water-use efficiency and fertilizer-use efficiency. These efficiency advantages of the closed system, the authors concluded, would lead to reduced pollution and financial benefits. They also mentioned that, while the applied solution had a pH of 5.5 to 6.0 and an electroconductivity (EC) of 1.8 to 2.3 dS/m, the drained solution had a pH of 6.3 to 7.2 and an EC of 3.1 to 5.5 dS/m. They attributed the increase in pH to the ammonium/nitrate ratio and the increase in EC to the plant taking up more water than nutrients. [The authors cited Herrero et al. (2014) - see below.]


• Herrero, B., Blázquez, M. E., & Cristóbal, M. D. (2014). Agronomic parameters assessment in hydroponic tomato crop. Horticultura Brasileira, 32(4), 385-390.
  
  Herrero et al. found pH and salinity differences in drainage between tomato crops grown in recirculating vs non-recirculating hydroponic production systems. They reported that overall fruit yield was not different between the two systems but that smaller fruits were significantly more abundant in the non-recirculating system, which could be a result of their methods, in which the non-recirculating system had a higher salinity. The study also showed that there were water savings from the use of the recirculating system, though not as great as those reported by others making similar comparisons.