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ORIGINAL RESEARCH article

Front. Plant Sci.

Sec. Plant Physiology

Effect of end-of-production light treatment under different light/dark alternating frequencies on ascorbic acid accumulation and metabolism of hydroponic lettuce

Provisionally accepted
Dong  YuDong Yu1Zonggeng  LiZonggeng Li2Jiangtao  HuJiangtao Hu2Fang  WangFang Wang2Wei  LuWei Lu1Quan  YuanQuan Yuan2Sen  WangSen Wang2Chengbo  ZhouChengbo Zhou2*Qichang  YangQichang Yang2
  • 1College of Horticulture, Sichuan Agricultural University, Chengdu, China
  • 2Institute of Urban Agriculture Chinese Academy of Agriculture, Chengdu, China

The final, formatted version of the article will be published soon.

This study investigated the effects of different light/dark alternation cycles on ascorbic acid (AsA) metabolism and oxidative stress in hydroponic lettuce under end-of-production (EOP) conditions characterized by high light intensity and a high blue-light ratio (500 μmol·m⁻²·s⁻¹, red: blue = 1:1). Four treatments were applied: RB1 (continuous illumination), RB2 (4 h light/4 h dark/4 h light), RB4 (three cycles of 2 h light/2 h dark plus a final 2 h light), and RB8 (seven cycles of 1 h light/1 h dark with a final 1 h light). The results revealed that AsA content exhibited an initial increase followed by a decrease with increasing alternation frequency, peaking under the RB2 treatment. Specifically, RB2 achieved the highest AsA accumulation, which was 11.8%, 28.5%, and 41.6% greater than in RB1, RB4, and RB8, respectively. This enhancement was attributed to the synchronous upregulation of the gene expression and enzymatic activity of GLDH, as well as key enzymes in the ascorbate-glutathione cycle (APX, MDHAR, and DHAR). Oxidative stress indicators (H2O2, MDA) decreased with increased light/dark alternation frequency. Therefore, the RB2 treatment, by coordinating reactive oxygen species (ROS) induction and promoting the simultaneous upregulation of expression and activity in the AsA metabolic enzyme system, serves as an energy-efficient strategy for improving the nutritional quality of lettuce in controlled environments.

Keywords: Ascorbic acid (AsA), light/dark alternating, End-of-production (EOP), reactiveoxygen species (ROS), Hydroponic lettuce

Received: 08 Aug 2025; Accepted: 10 Nov 2025.

Copyright: © 2025 Yu, Li, Hu, Wang, Lu, Yuan, Wang, Zhou and Yang. 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: Chengbo Zhou, zhouchengbo@caas.cn

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