The effect of foliar applications of a bio-stimulant derived from algae extract on the physiological behavior of lulo seedlings (Solanum quitoense cv. Septentrionale). Cien. Inv. Agr. 43(1):25-37. Seaweed extracts are used as nutritional supplements, biostimulants, or biofertilizers in agriculture and horticulture to increase plant growth and yield. In this experiment, foliar applications of bio-stimulant derivate from seaweed extract were tested on plant growth, leaf gas exchange properties, and proline accumulation in lulo seedlings cultivated under greenhouse conditions. Lulo plants were split into four treatments: (i) plants with soil fertilizer; (ii) plants treated only with foliar bio-stimulant sprays; (iii) a combination of soil fertilizer plus a foliar bio-stimulant application; and (iv) a control treatment (without nutrient application). Lulo plants treated with soil fertilizer and foliar bio-stimulants increased growth, as this group of plants showed a higher total plant dry weight, stem diameters, and absolute growth rate. Lulo plants without soil fertilizater and treated with foliar bio-stimulant application had lower leaf gas exchange (photosynthesis, stomatal conductance, and plant transpiration) and leaf chlorophyll content. Foliar bio-stimulant sprays enhanced the partitioning of dry mass in floral cushions. In conclusión, the application of foliar bio-stimulant applications as a complement to soil fertilizer is a technique that can be employed in the cultivation of lulo because foliar sprays of these kinds of agrochemicals can enhance dry matter accumulation and blooming.