The experiment object was to compare the effects of the partial rootzone drying (PRD) and the deficit irrigation (DI) strategies applied with 50% of water requirements on leaf stomatal conductance, signal intensity, root development and water use efficiency (WUE) of tomato grown under greenhouse and on soilless. Three treatments were applied: control that was fully and conventionally irrigated, PRD and DI in which 50% of water requirements were applied using PRD and DI irrigation strategies, respectively. For PRD treatment, alternation between the two rootzone sides took place each three days. When vapor pressure deficit rises, PRD and DI stomatal conductance was 26% and 15% respectively lower than control. The comparison between treatments in terms of signal intensity revealed a better resistance to water deficit for PRD-50. Root profile results corroborated previous findings. In fact, when compared to Control, the total number of root hairs is increased by 11% and 90% for DI-50 and PRD-50, respectively. Compared to control, water use efficiency was improved for both treatments: DI and PRD were, respectively, 155% and 160% more efficient.