BIOFORTIFICAÇÃO AGRONÔMICA DE ALFACES TROPICALIZADAS SOB DIFERENTES ESPECTROS DE LUZ LED

Abstract

Vertical cultivation of vegetables represents a strategic alternative for food security in the face of climate change. Despite technological advances, there is still a gap in the scientific literature regarding the biofortification potential of tropicalized genotypes, especially when combined with productive stability in systems with artificial lighting. The objective of this study was to evaluate the morphophysiological, nutritional, and productive performance of four lettuce genotypes: the commercial cultivar Grand Rapids (non-tropicalized) and the lines UFU-155#1#1#1, UFU-189#1#2#1, and UFU Biofort (tropicalized). The genotypes were subjected to different LED light spectra (red, blue, white and the combination of the three previous ones, being RBW)) in a vertical aeroponic system cultivated indoors. Evaluations were made of gas exchange, chlorophyll a fluorescence, agronomic parameters, and determination of nutritional composition. Results showed a significant interaction between the studied factors, demonstrating that the light increased quantum efficiency (Fv/Fm) in the UFU-155#1#1#1 and UFU-189#1#2#1 lines (averages above 0.80), while red light reduced the performance index (Pi_Abs) in UFU-Biofort to values close to 1.5. Agronomically, red light maximized total fresh mass and plant diameter, despite reducing stomatal conductance (gs). The intrinsic efficiency of water use (A/gs) was significantly higher in UFU-189#1#2#1 under red light (114.8 µmol CO2/mol H2O), favored by the increase in specific leaf mass and leaf thickness (0.37 mm). The UFU-189#1#2#1 line stood out under the RBW spectrum, presenting high levels of Mg (7.45 g kg-1), Mn (292 mg kg-1), and Zn (605.37 mg kg-1). The red spectrum promoted growth in length but induced physiological stress and reduced photosynthesis, while the blue and RBW spectra optimized the stomatal apparatus, with stomatal densities exceeding 800 mm2 on the abaxial surface, increasing chlorophyll levels and nutritional biofortification. The tropicalized lines UFU-Biofort and UFU-189#1#2#1 showed greater suitability for indoor cultivation and photochemical efficiency, surpassing the commercial cultivar Grand Rapids in structural robustness and nutritional density, with levels of biofortification considered relevant for human consumption and food safety.