Lettuce growth promoted by artificial lighting using light-emitting diodes (LED)

Understanding how the use of light-emitting diodes (LED) in artificial lighting affects plant growth is of considerable interest to Science because the application of specific light wavelengths to crops can enhance agricultural production. Therefore, the influence of LED lamps in the photosynthetically active spectrum (blue and red light) on the growth of lettuce (Lactuca Sativa) was evaluated. A factorial design was used to test 4 combinations of LED lighting (5:1; 3:1; 1:1 and 6:3) and 2 lettuce varieties (butterhead and crisphead). The plants were grown in pots in a controlled environment with a 12h-photoperiod, for 21 days. Leaf number (LN), leaf area (LA) and leaf fresh mass (LFM) were determined along with gas exchange variables (A: net photosynthesis; Ci: CO2internal concentration; and WUEi: instantaneous water use efficiency. Growth of lettuce plants was greatest in the source of variation of LED lighting with the combination 5:1, as well as the greatest photosynthetic efficiency. The crisphead lettuce was superior to the butterhead lettuce in all analyzed variables, which suggests a better adaptation to the treatments applied.