Productive aspects and operating costs of hydroponic lettuce under different nutrient solution flow rates

Producing leafy vegetables in intensive hydroponic systems requires knowledge of production cost variables and their proper management. Flow rate is a decisive factor in both production and operating costs as it directly affects energy consumption. This study aimed to assess the productive aspects of lettuce in relation to nutrient solution flow rate and energy consumption in a nutrient flow technique hydroponic system. The experiment was conducted on individual benches, with treatments consisting of five nutrient solution flow rates: 0.5; 1.0; 1.5; 2.0 and 2.5 liters per minute (L/min). Production components and water pump operating costs were assessed. Average plant production was 250.5, 282.75, 316, 338.5 and 346.6 g for flow rates of 0.5, 1.0, 1.5, 2.0 and 2.5 L/min, respectively. The lowest operational energy costs and the highest production performance was observed at a flow rate of 1.5 L/min, while, reduced performance was noted at flow rates of 0.5 and 1.0 L/min. The different water management strategies evaluated indicate the feasibility of operating in a hydroponic system, considering all cost-benefit (C/B) ratios > 1.