Performance of a membrane-based irrigation system for different evaporative conditions

Abstract. A study was conducted to evaluate the effect of differing evaporative demand on the performance of a novel membrane-based irrigation system when two membranes (RO and FO-Toray) were compared during the germination of common bean (Phaseolus vulgaris L.). After seedling establishment, the study also considered the effects of high and low controlled evaporative demand inside growth cabinets and salinity levels of 0.3 and 3.3 dS/m in a 3x2x2 completely randomized factorial in triplicate. The germination performance was evaluated by means of first counting, germination percentage, coefficient of uniformity of germination, mean germination time and germination rate. A better performance was presented by the FO-Toray membrane in comparison to the RO, as the evapotranspiration observed for the FO-Toray was generally statistically equal to the control over the experiment‘s duration. For germination percentage, a significant difference was not observed between FO and control (89.6 and 90%, respectively), while the RO presented germination 25% lower. No significant difference was observed for soil EC for the highest salinity level; however, a longer experiment for further studies of salinity is recommended. The proposed method for irrigation based on membrane technology has demonstrated the ability to meet crop water demand when the environmental evaporative demand, controlled by changes in T and RH, and salinity were increased. The study also emphasizes the importance of membrane selection on the irrigation system‘s water delivery and salt rejection.