Abstract
With the rise of plant factories around the world, more and more crops are cultivated under artificial light. Studies on effects of lighting strategies on plant growth, such as different light intensities, photoperiods, and their combinations, have been widely conducted. However, research on application of multi-segment light strategies and associated plant growth mechanisms is still relatively lacking. In the present study, two lighting strategies, multi-segment light intensity and extended photoperiod, were compared with a constant light intensity with a 12 h light/12 h dark cycle and the same daily light integral (DLI). Both lighting strategies promoted plant growth but acted via different mechanisms. The multi-segment light intensity lighting strategy promoted plant growth by decreasing non-photochemical quenching (NPQ) of the excited state of chlorophyll and increasing the quantum yield of PSII electron transport (PhiPSII), quantum yield of the carboxylation rate (PhiCO2), and photochemical quenching (qP), also taking advantage of the circadian rhythm. The extended photoperiod lighting strategy promoted plant growth by compensating for weak light stress and increasing light-use efficiency by increasing chlorophyll content under weak light conditions.
Highlights
Plant factories with artificial lighting (PFAL) are a relatively new method of efficient agricultural cultivation that are becoming more and more important in combatting increasingly serious global food supply problems [1]
Crops in PFALs always rely on artificial lighting in that the light energy drives photosynthesis, which means that electricity accounts for 25%–30% of the total production costs and that light sources account for the majority of all energy consumption, about 60%–80% [1]
Our results suggested that the lettuce plants in the extended photoperiod lighting strategy (A) had a higher ability to use weak light than the lettuce cultivated under the short photoperiod lighting strategy (B)
Summary
Plant factories with artificial lighting (PFAL) are a relatively new method of efficient agricultural cultivation that are becoming more and more important in combatting increasingly serious global food supply problems [1]. Improving the efficiency of light sources would greatly reduce the cost of PFALs, which would further encourage their sustainable development because costs and ecological impacts could be reduced. In PFALs, light energy can be provided for crops at any time because day and night no longer determine lighting schedules. This means that any photoperiod can be chosen to optimize the growth
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