The open system represents one of the most common approaches to soilless cultivation in Iran, where drainage water from the growth medium is not recirculated and is typically discarded. This practice may lead to chemical pollution and soil salinity issues. In this study, we developed a lab-scale drip irrigation system for open-system soilless culture, equipped with sensors to monitor drainage levels in selected cultivation rows, and evaluated its performance metrics. The research comprised two experimental phases. The first phase examined the effects of emitter flow rate, drainage percentage, and pot ratio (defined as the ratio of main pots to control unit pots) on system error percentage. The lsecond phase investigated the impact of varying drainage percentages (5%, 10%, 15%, and 20%) on morphological growth parameters of greenhouse cucumber plants, with a control group using conventional irrigation practices. Results demonstrated statistically significant differences (p<0.05) between the 5% and 10% drainage treatments when compared both with each other and with the 15%, 20%, and control groups, showing reduced yield performance at lower drainage levels. However, no significant differences were observed among the 15%, 20%, and control treatments. The optimal drainage percentage of 15% enabled over 13% savings in water and fertilizer inputs while maintaining yield comparable to conventional irrigation.
Sarayani et al. (Sun,) studied this question.