<![CDATA[Red lettuce (Lactuca sativa L.) is a vegetable with high economic and nutritional value that can be cultivated in hydroponic systems. The success of hydroponic cultivation is influenced by nutrient availability. However, the use of Plant Growth-Promoting Rhizobacteria (PGPR) as a biological stimulant combined with various nutrient sources in hydroponic systems is still not widely used. This study aimed to analyze the effectiveness of nutrient types and PGPR concentrations on the growth and yield of red lettuce grown in a floating raft hydroponic system. The experiment was conducted at the Integrated Field Laboratory Greenhouse, Faculty of Agriculture, University of Lampung, from February to March 2026 was designed as 2 × 4 factorial Randomized Complete Block Design (RCBD) with three replications. The first factor was the type of nutrient used, which included of AB-mix (N1) and Growmore 32-10-10 (N2). The second factor was the concentration of PGPR, which included of 0 mL/L (P0), 8 mL/L (P1), 16 mL/L (P2), and 24 mL/L (P3). The results showed that AB-mix produced higher growth and yield of red lettuce than Growmore 32-10-10 across all observed variables. Each incremental increase in PGPR concentration up to 24 mL/L improved the growth and yield of red lettuce across all observed variables. The interaction between nutrient type and PGPR concentration indicated that AB-mix resulted in greater growth and yield responses than Growmore 32-10-10. In addition, root components (root length, root fresh weight, and root volume) were very strongly correlated with plant fresh weight.]]>
