Foliar and Root Applications of Vegetal-Derived Protein Hydrolysates Differentially Enhance the Yield and Qualitative Attributes of Two Lettuce Cultivars Grown in Floating System

Lettuce (Lactuca sativa L.) is a leafy vegetable cultivated widely for its fast and year-round production beneficial phytochemical content, which may be boosted further by plant biostimulants that are considered eco-sustainable means enhancing horticultural crop production. A greenhouse experiment was carried out to evaluate the yield qualitative parameters of two differently pigmented lettuce cultivars grown in floating raft system either untreated or treated (leaf, root leaf/root application) with vegetal protein hydrolysates (PHs). For foliar application (F), plants were sprayed at dose 3 mL L−1, whereas application, 0.15 (T1) 0.3 (T2) L−1 applied nutrient solution alone combination spray (T1 + F T2 F) same concentration. Bio-morphometric data collected after harvest. Physiological nutrition assays included leaf gas exchange, fluorescence, SPAD index, mineral carotenoids, total phenols, ascorbic acid content antioxidant activities. Cultivar-specific reactions biostimulant noted: whilst green cultivar thrived under applications recorded higher 82.7% 71.7% (T2), red combined treatments, yielding 55.4% (T2 than control providing most concentrated content. These latter treatments also engendered highest Fv/Fm ratio, CO2 assimilation, stomatal conductance transpiration. In addition, treatment ‘Canasta’ hydrophilic activity (21.9%) (5.6-fold). Nutrient proved advantageous when compared while mixed genotype-specific. New research on genotype specificity effects warranted future use, order rationalize modes dosages.