Intelligent Equipment Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China.
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
Sci Rep. 2022 Apr 28;12(1):6924. doi: 10.1038/s41598-022-10681-3.
To investigate the effects of extended light/dark (L/D) cycle period (relative to the diurnal L/D cycle) on lettuce and explore potential advantages of abnormal L/D cycles, butter leaf lettuce were grown in a plant factory with artificial light (PFAL) and exposed to mixed red (R) and blue (B) LED light with different L/D cycles that were respectively 16 h light/8 h dark (L16/D8, as control), L24/D12, L48/D24, L96/D48 and L120/D60. The results showed that, all the abnormal L/D cycles increased shoot dry weight (DW) of lettuce (by 34-83%) compared with the control, and lettuce DW increased with the L/D cycle period prolonged. The contents of soluble sugar and crude fiber in lettuce showed an overall upward trend with the length of L/D cycle extended, and the highest vitamin C content as well as low nitrate content were both detected in lettuce treated with L120/D60. The light use efficiency (LUE) and electric use efficiency (EUE) of lettuce reached the maximum (respectively 5.37% and 1.76%) under L120/D60 treatment and so were DW, Assimilation rate (A), RC/CS, ABS/CS, TR/CS and DI/CS, indicating that longer L/D cycle period was beneficial for the assimilation efficiency and dry matter accumulation in lettuce leaves. The highest shoot fresh weight (FW) and nitrate content detected in lettuce subjected to L24/D12 may be related to the vigorous growth of root, specific L/D cycle seemed to strengthen root growth and water absorption of lettuce. The openness level of RC in PSII (Ψ), ET/CS, and PI were all the highest in lettuce treated with L24/D12, implying that slightly extending the L/D cycle period might promote the energy flowing to the final electron transfer chain. In general, irradiation modes with extended L/D cycle period had the potential to improve energy use efficiency and biomass of lettuce in PFAL. No obvious stress or injury was detected in lettuce subjected to prolonged L/D cycles in terms of plant growth and production. From the perspective of shoot FW, the optimal treatment in this study was L24/D12, while L120/D60 was the recommended treatment as regards of the energy use efficiency and nutritional quality.
为了研究延长光/暗（L/D）周期（相对于昼夜 L/D 周期）对生菜的影响，并探索异常 L/D 周期的潜在优势，采用人工光植物工厂（PFAL）和红蓝（R、B）混合 LED 光对生菜进行了研究，其 L/D 周期分别为 16 小时光照/8 小时黑暗（L16/D8，作为对照）、L24/D12、L48/D24、L96/D48 和 L120/D60。结果表明，与对照相比，所有异常 L/D 周期均增加了生菜的地上部干重（DW）（增加了 34%-83%），且随着 L/D 周期的延长，生菜 DW 增加。随着 L/D 周期的延长，生菜中可溶性糖和粗膳食纤维的含量呈总体上升趋势，L120/D60 处理的生菜中维生素 C 含量最高，硝酸盐含量最低。L120/D60 处理下生菜的光能利用率（LUE）和电能利用率（EUE）达到最大（分别为 5.37%和 1.76%），DW、同化率（A）、RC/CS、ABS/CS、TR/CS 和 DI/CS 也达到最大，表明较长的 L/D 周期有利于生菜叶片的同化效率和干物质积累。生菜中检测到的最高地上部鲜重（FW）和硝酸盐含量可能与根的旺盛生长有关，特定的 L/D 周期似乎增强了生菜的根生长和吸水能力。在 L24/D12 处理下，PSII 中 RC 的开放程度（Ψ）、ET/CS 和 PI 均达到最高，这表明略微延长 L/D 周期可能会促进能量流向最终电子传递链。总的来说，延长 L/D 周期的辐照模式有可能提高 PFAL 中生菜的能量利用效率和生物量。在延长 L/D 周期的情况下，生菜的生长和产量没有明显的压力或损伤。从地上部 FW 来看，本研究的最佳处理是 L24/D12，而从能量利用效率和营养品质来看，推荐的处理是 L120/D60。
