Responses of butter leaf lettuce to mixed red and blue light with extended light/dark cycle period

Xiao-Li Chen; You-Li Li; Li-Chun Wang; Qi-Chang Yang; Wen-Zhong Guo

doi:10.1038/s41598-022-10681-3

Responses of butter leaf lettuce to mixed red and blue light with extended light/dark cycle period

Sci Rep. 2022 Apr 28;12(1):6924. doi: 10.1038/s41598-022-10681-3.

Authors

Xiao-Li Chen¹, You-Li Li¹, Li-Chun Wang¹, Qi-Chang Yang², Wen-Zhong Guo^{3

4}

Affiliations

¹ Intelligent Equipment Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China.
² Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, China. yangqichang@caas.cn.
³ Intelligent Equipment Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China. guowz@nercita.org.cn.
⁴ Key Laboratory of Urban Agriculture (North China), Ministry of Agriculture and Rural Affairs, Beijing, China. guowz@nercita.org.cn.

Abstract

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_o/CS and DI_o/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_o), ET_o/CS, and PI_abs 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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Butter
Lactuca*
Light
Nitrates / analysis
Photosynthesis* / radiation effects

Substances

Nitrates
Butter