Chen Ren, Wang Zhenwei, Liu Wenke, Ding Yuteng, Zhang Qishuan, Wang Shurong
Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528225, China.
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Plants (Basel). 2023 Dec 13;12(24):4147. doi: 10.3390/plants12244147.
A plant factory with artificial lighting (PFAL) usually uses top lighting for cultivation. The light from the upper part of the canopy cannot penetrate the entire lettuce canopy, however, resulting in uneven vertical spatial light in the canopy, and accelerating the senescence of both the bottom and side leaves of the plant canopy. Therefore, in this study, the performance of lettuce in hydroponics was investigated upon supplemental side lighting with different spectral LEDs in a PFAL. A set of short-term side lighting treatments, including no side lamps (CK), red (R), blue (B), red + blue (RB), and red + blue + green (RGB) LED lamps (150 μmol·m·s, respectively), was employed for an additional 2 h per day after normal top lighting for 6 days before harvest. The results showed that the lettuce canopy was relatively loose and had a large crown size under side lighting compared with CK. Side lighting, irrespective of spectral qualities, significantly increased the fresh weight, and the R, B, RB, and RGB treatments increased the shoot fresh weight of lettuce plants by 34%, 19%, 31%, and 34%, and increased the fresh weight of leaf layer 2 by 50%, 17%, 44%, and 48%, respectively. The side lighting of different spectral qualities had a significant impact on the nutritional quality of the first row of lettuce at the edge of the top lighting illuminated area. Treatment B significantly promoted the chlorophyll content of leaf layer 3; the soluble sugar contents from leaf layer 1, 2, and 3; the starch contents in leaf layers 2 and 3; and the content of phenolics in the leaf layers 3; and significantly reduced the nitrate content in leaf layers 2 and 3. RGB significantly increased soluble sugar content by 91%, and the starch content in leaf layer 1, as well as the leaf chlorophyll and flavonoid content of leaf layer 3, while R had opposite effect completely. RB significantly increased the leaf chlorophyll content of leaf layer 3 and the nitrate content in leaf layer 1, but the overall effect was lower than that of RGB. In summary, side lighting of any type could effectively improve lettuce yield, solve the problem of inconsistent lettuce plant size caused by the edge effect of top lighting, and affect the nutritional quality of lettuce. B and RGB performed best. There was spatial response diversity of lettuce plants to side lighting spectral qualities.
人工光照植物工厂（PFAL）通常采用顶部照明进行栽培。然而，冠层上部的光线无法穿透整个生菜冠层，导致冠层内垂直空间光照不均匀，并加速了植株冠层底部和侧面叶片的衰老。因此，在本研究中，在人工光照植物工厂中，研究了在补充不同光谱的发光二极管（LED）进行侧面补光时水培生菜的生长表现。在收获前6天，正常顶部照明后，每天额外进行2小时的一组短期侧面照明处理，包括不使用侧灯（CK）、红色（R）、蓝色（B）、红色+蓝色（RB）和红色+蓝色+绿色（RGB）LED灯（光强均为150 μmol·m·s）。结果表明，与CK相比，侧面补光下生菜冠层相对疏松，冠幅较大。无论光谱质量如何，侧面补光均显著增加了鲜重，R、B、RB和RGB处理使生菜植株地上部鲜重分别增加了34%、19%、31%和34%，使第2叶层鲜重分别增加了50%、17%、44%和48%。不同光谱质量的侧面补光对顶部照明照射区域边缘第一排生菜的营养品质有显著影响。B处理显著提高了第3叶层的叶绿素含量、第1、2、3叶层的可溶性糖含量、第2和3叶层的淀粉含量以及第3叶层的酚类物质含量，并显著降低了第2和3叶层的硝酸盐含量。RGB处理使可溶性糖含量显著增加了91%，第1叶层的淀粉含量以及第3叶层的叶片叶绿素和类黄酮含量显著增加，而R处理则完全相反。RB处理显著增加了第3叶层的叶片叶绿素含量和第1叶层的硝酸盐含量，但总体效果低于RGB处理。综上所述，任何类型的侧面补光均可有效提高生菜产量，解决顶部照明边缘效应导致生菜植株大小不一致的问题，并影响生菜的营养品质。B和RGB处理效果最佳。生菜植株对侧面补光光谱质量存在空间响应多样性。
