Background and Objective: As the world's population increases, efforts are to produce more food. The growth of vegetables requires a certain generation time that limits the amount obtained from them. The present study was initiated to evaluate the speed and capacity of lettuce plant growth in a red-blue LED sunless lighting model. Methodology: Lettuce seed were insert in 20 black plastic (polypropylene) seed beds 54×28 cm plates; each one with 288 alveoli (diameter 1.9 cm depth 3 cm). Plates were randomized in two groups (LED illumination or control sunlight group during 30 days)-10 plate each group-. Artificial lighting device consists of 6 LED modules (3 red and 3 blue LED modules) to form a purple color. Root length, plant height, relation height/root, number of leaves, aerial part of the plant and an index of greenery (SPAD unit) were variables included in the study. These variables were measured at the beginning of the experience and also at day 7th,15th and at day 21sth of the experience. Statistical method used was one way ANOVA using the Stat-graphics Centurion program. The mean values obtained were compared using the LSD test with a significance of p <0.05 with a confidence interval of 95%. Results: The number of leaf and root length was similar in both groups. Root length was similar. However, leaf area, leaf/root relation, overall height of plant and SPAD units were increased in LED lighting compared with sunlight growth. Conclusion: The purple LED lighting model is a valid option to induce lettuce production in sunless conditions.Facultad de Ciencias MédicasInstituto de Fisiología VegetalFacultad de Ingenierí
