Hydroponic Lettuce and Spinach Production Under Controlled Environments in Urban Pakistan: Growth, Nutritional Quality, and Water-Use Efficiency of NFT and DWC Systems

Rapid urbanization and intensifying water scarcity are placing conventional food-production systems in Pakistan under acute strain, creating an urgent need for resource-efficient alternatives suited to cities.This study evaluated the growth, marketable yield, nutritional quality and water-use efficiency of loose-leaf lettuce (Lactuca sativa L. 'Grand Rapids') and flat-leaf spinach (Spinacia oleracea L. 'Viroflay') grown in two soilless systems, the Nutrient Film Technique (NFT) and Deep Water Culture (DWC), against a conventional soil-based control.Hydroponic treatments were applied at three nutrient-solution electrical conductivities (EC1 = 1.5, EC2 = 2.5 and EC3 = 3.5 mS cm⁻¹) in a controlled-environment facility in Rawalpindi, Pakistan, using a completely randomized design with a factorial arrangement, from March to June 2024.NFT at EC3 produced the highest marketable yields (lettuce 4.2 kg m⁻² and spinach 3.7 kg m⁻²), representing increases of 133% and 147% over the soil control, respectively.Nitrate concentrations in all hydroponic produce remained well within international food-safety limits, while vitamin C, leaf chlorophyll (SPAD), total soluble solids and crude protein were significantly higher than in soil-grown plants.Water use in the NFT system was about 90% lower than in conventional cultivation (18.4 versus 186.3 L kg⁻¹ fresh weight).Although hydroponic production costs were higher, retail price premiums for pesticide-free produce yielded favourable economic margins.The results provide baseline, locally grounded evidence supporting the introduction of controlled-environment hydroponics into urban food systems in Pakistan.