ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Crop and Product Physiology
Volume 16 - 2025 | doi: 10.3389/fpls.2025.1621513
Extended Photoperiod Improves Growth and Nutritional Quality of Pak Choi Under Constant Daily Light Integral
Provisionally accepted
- 1Department of Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
- 2singapore food agency, singapore, Singapore
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The duration of light exposure each day, termed the photoperiod, is a crucial environmental cue that influence several aspects of plant physiology, including growth, development, and metabolic activity.Adjusting the photoperiod in controlled agriculture systems has the potential to improve crop yield and nutritional content. However, the benefits of longer photoperiods compared to higher light intensities under a fixed daily light integral (DLI) have not been thoroughly examined for many leafy vegetables. DLI is the total amount of light a plant receives per day and it is the product of photoperiod and light intensity.This study aimed to determine to what extent the effect of DLI on pak choi (Brassica rapa L. subsp. chinensis) growth, yield and quality depends on whether DLI is changed by light intensity (PPFD) or by photoperiod. Three cultivars ('Hybrid Special', 'Red Summer', and 'Shanghai Green') were grown under four different DLIs (10.8, 13.5, 16.2, and 18.9 mol m -2 d -1 ). These DLIs were achieved either by varying the photoperiod (12, 15, 18 and 21 hours) at a constant PPFD 250 µmol m -2 s -1 or by varying the PPFD (167, 208, 250, and 292 µmol m -2 s -1 ) at a constant photoperiod (18 hours). Increasing DLI by extending the photoperiod resulted in more growth than increasing DLI by increasing PPFD. Photoperiod extension also generally resulted in higher light use efficiency and energy use efficiency than increasing DLI by increasing PPFD. The content of vitamin C, glucosinolates and many other metabolites increased significantly with higher DLI regardless whether DLI was increased through PPFD or photoperiod. However, DLI did not affect shelf life and overall visual quality.
Keywords: photoperiod, light intensity, Pak choi, vitamin C, LUE, PSM, sole LED lights
Received: 01 May 2025; Accepted: 23 Jun 2025.
Copyright: © 2025 Susilo, Eu, Besemer, Heuvelink, De Vos and Marcelis. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Ep Heuvelink, Department of Plant Sciences, Wageningen University and Research, Wageningen, 6700AA, Netherlands
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