Growth, morphology, photosynthetic performance, and energy use efficiency as affected by different combinations of light wavelength in a plant factory with artificial light
Light, as energy and signal source for plant growth and development, is one of the most important environment factors in recently developed plant factories with artificial light (PFAL). To find an optimum light wavelength for lettuce (Lactuca sativa L. 'Tiberius') plant growth in a PFAL, four treatments by using a mixture of red (662 nm) and blue light (447 nm) with an R/B ratio of 4:1 and light intensity of 150 μmol m‑2 s‑1 and supplementing with 50 μmol m‑2 s‑1 green light (525 nm, RBG), yellow light (592 nm, RBY), orange light (605 nm, RBO) and far-red light (742 nm, RBFR), respectively, were set up in this experiment. The mixture of red (662 nm) and blue light (447 nm) with an R/B ratio of 4:1 and light intensity of 200 μmol m‑2 s‑1 was set as the control (RB). The responses of lettuce growth, morphology, photosynthetic performance and energy use efficiency on different combinations of light wavelength were investigated. The results showed that: 1) RBG, RBO and RBFR increased the fresh shoot weight of lettuce by 20.5, 19.6, and 40.4%, and increased the dry shoot weight of lettuce by 33.4, 27.2 and 37.5% compared with the control, respectively; 2) the net photosynthetic rate under RBY was significantly lower than that of control, although the chlorophyll and carotenoid concentration of the lettuce grown under RBY had no significant difference compared with RB; 3) RBG could increase the lettuce plant height, leaf area, net photosynthetic rate and energy use efficiency; 4) RBO showed a better photosynthetic performance compared with the rest treatments, simultaneously, the energy use efficiency was the increased; 5) RBFR caused increases in shoot height and leaf area, but lettuce grown under this condition showed some defects such as easy to get tip-burn. Thus, the above results indicated that RBG and RBO can be considered as the optimum combinations of light wavelength for lettuce growth in a PFAL, although lettuce plant growth also can be improved by using RBFR light.
Li, L., Tong, Y.X. and Yang, Q.C. (2020). Growth, morphology, photosynthetic performance, and energy use efficiency as affected by different combinations of light wavelength in a plant factory with artificial light. Acta Hortic. 1296, 959-966
light quality, morphology, photosynthesis, photon yield, lettuce