Received: Oct 27, 2025 / Accepted: Feb 10, 2026 / Published: Jun 30, 2026
The study investigated the effects of fish protein hydrolysate (FPH), derived from fish processing by-products, on the growth, yield, and quality of lettuce (Lactuca sativa L.) grown in a static hydroponic system. Four nutrient treatments were evaluated: a control using a commercial inorganic Snap solution (T1) and three FPH-based solutions at concentrations of 300ppm (T2), 600ppm (T3), and 900ppm (T4). Results showed that the 600ppm FPH treatment (T3) significantly enhanced plant growth and physiological performance compared with the control. Lettuce under T3 achieved the greatest root length (21.4cm), canopy diameter (27.6cm), SPAD value (38.5), and fresh yield (438.2 g plant-1), representing a 22-30% increase over T1. Quality attributes also improved under moderate FPH application. Vitamin C content increased to 10.5 mg 100 g-1 in T3 compared with 7.5 mg 100 g-1 in the control, while nitrate concentration decreased markedly from 398.5 to 242.1 mg 100 g-1. Soluble solids content rose from 3.7 to 4.2°Brix, indicating improved sweetness and flavor. No Escherichia coli or Salmonella spp. contamination was detected in any treatment, confirming product safety. Overall, the application of 600ppm FPH provided an optimal balance between yield, nutritional quality, and microbial safety. These findings demonstrate that fish protein hydrolysate offers a cost-effective and sustainable nutrient alternative for hydroponic lettuce production, promoting circular resource utilization and environmentally friendly agriculture.
