The use of biochar as a soil conditioner has been widely investigated due to its potential to mitigate nutrient loss in agricultural soils, offering a sustainable alternative to intensive mineral fertilization. This study was conducted to evaluate the impact of increasing biochar rates on the productivity and morphological characteristics of red lettuce (Lactuca sativa L. cv. Scarlet) grown in a lowfertility Oxisol, in a succession system following arugula. The experiment was conducted in a greenhouse, in a completely randomized design (CRD), consisting of six treatments corresponding to rates of 0 %, 0.8 %, 1.6 %, 2.4 %, 3.2 %, and 4.0 % biochar incorporated into the substrate, with five replicates. The biochar was derived from the pyrolysis of sugarcane bagasse. Plants were harvested 30 days after transplanting and evaluated for morphological and biomass parameters. Total leaf number, stem diameter, and total fresh mass did not differ significantly among treatments. However, a significant increase was observed in marketable fresh mass and leaf dry mass at biochar rates between 1.6 % and 4.0 % compared with the 0 % and 0.8 % treatments. The results indicate that biochar, even in lowfertility soils and crop succession systems, improves marketable biomass and leaf dry mass accumulation in red lettuce, although the effect on primary morphological characteristics was limited, suggesting that the material enhances nutrient retention essential for productivity.
