Effect of Treated Wastewater Quality on Agronomic Performance, Yield, and Nutritional Composition of Tomato (Solanum lycopersicum L.)

Water scarcity in Mediterranean regions such as Morocco makes treated wastewater a strategic alternative for irrigation. This field study evaluated the effects of two treated wastewater sources, membrane bioreactor T2 and activated sludge T3, compared with groundwater (T1, control) on growth, yield, and fruit quality of two tomato cultivars (Solanum lycopersicum L., Bobcat and Galilia). Irrigation with activated sludge effluent T3 significantly improved agronomic performance relative to both MBR-treated water and groundwater. Under T3, plant height reached 158 ± 3.5 cm in Galilia and 150 ± 3.2 cm in Bobcat, while fruit yield increased to 9.93 ± 0.38 kg plant−1 in Bobcat and 7.12 ± 0.25 kg plant−1 in Galilia, more than double the yield recorded under T2. Physiological parameters such as chlorophyll a, proline, and soluble sugars increased markedly under T3, indicating enhanced photosynthetic activity and improved stress tolerance. Fruit quality was enhanced under T3, with higher soluble sugar and protein levels, while lycopene and acidity were greatest under groundwater irrigation. Overall, the results demonstrate that secondary treated wastewater, particularly from activated sludge processes, can sustainably improve tomato yield and quality while conserving freshwater resources in arid regions. These findings demonstrate the potential of treated wastewater as a sustainable irrigation source for water-scarce Mediterranean agriculture.