Evaluation of Chlorella vulgaris application as a biostimulant for lettuce growth in soilless culture

This study evaluated the effect of Chlorella vulgaris application on the growth of soilless-grown lettuce (Lactuca sativa cv. 'Oreja de Mulo') cultivated outdoors. Microalgae suspensions were applied weekly at concentrations of 0.5, 2.0, and 5.0 g L(-)1. Plants grown without the application of microalgae were used as the control. Leaf chlorophyll concentration was registered at the beginning and at the end of the experiment, and biomass parameters were assessed at harvest. Compared with control, the highest concentration of C. vulgaris (CV5) exhibited the maximum increase in leaf area (67.4%), root fresh weight (138.7%), root volume (92.1%) and root dry weight (150.0%). This concentration further promoted higher accumulation of nitrogen (44.9%), phosphorus (96.4%), potassium (59.5%), and iron (Fe) (43.8%) in aerial parts of the lettuce plants These findings demonstrate the potential of C. vulgaris suspensions as effective biostimulants for improving growth, nutrient uptake, and biomass accumulation in hydroponic lettuce production, supporting more sustainable agricultural practices.