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ORIGINAL RESEARCH article

Front. Plant Sci.
Sec. Photosynthesis and Photobiology
Volume 15 - 2024 | doi: 10.3389/fpls.2024.1467443
This article is part of the Research Topic Enhancement of Photosynthesis through Light Utilization in Plants and Crops View all 9 articles

Lowering the Target Daily Light Integrals Following Days with Excessive Lighting Can Reduce Lettuce Production Costs

Provisionally accepted
Andres Mayorga-Gomez Andres Mayorga-Gomez Marc W. Van Iersel Marc W. Van Iersel Rhuanito S. Ferrarezi Rhuanito S. Ferrarezi *
  • University of Georgia, Athens, United States

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

    Given the fluctuating availability of natural lighting throughout the year, supplemental light is frequently employed to maintain the optimal daily light integral (DLI) levels necessary for adequate plant growth. However, the use of supplemental light translates into higher operational costs. Recent reports suggest that plants can tolerate a day with low DLI following exposure to a day with high DLI from natural light. This was referred to as the ‘carryover’ effect. In such cases, supplemental lighting may not be necessary, resulting in energy savings. In this study, we aimed to determine if plants can withstand such DLI fluctuations over multiple days without compromising plant growth. If successful, this could reduce energy consumption and generate significant monetary savings. To test this, we cultivated lettuce plants (Lactuca sativa cv. ‘Waldmand’s Dark Green’ and ‘Rouxai’) in a walk-in grow chamber, subjecting them to six different lighting treatments. Each treatment consisted of a day with a high DLI of 22.5 mol·m-2·d-1 followed by a varying number of consecutive days with low DLI, ranging from 1 to 5 days, with DLIs of 7.5, 11.25, 12.5, 13.13, and 13.5 mol·m-2·d-1 respectively. The combined DLI for each treatment, calculated as the average DLI across high and low DLI days, was maintained at 15 mol·m-2·d-1. Additionally, we included a control treatment where plants were exposed to a constant DLI of 15 mol·m-2·d-1. We measured plant growth rate, final fresh and dry weights, leaf number, leaf area, specific leaf area, light use efficiency, and relative pigment content to assess differences in plant growth under the different lighting regimes. We observed a decrease in biomass accumulation, as indicated by a 13% reduction in final dry weight only for the treatment involving one day of high DLI followed by one day of low DLI, compared to our control. We discovered that plants can tolerate multiple days of low DLI following a day with high DLI, in contrast to the optimal values reported in the literature. This finding can lead to reduced energy consumption for supplemental lighting and consequent operational cost savings

    Keywords: Lactuca sativa, Light levels, Energy, Supplemental light, Daily light integral

    Received: 19 Jul 2024; Accepted: 06 Nov 2024.

    Copyright: © 2024 Mayorga-Gomez, Van Iersel and Ferrarezi. 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: Rhuanito S. Ferrarezi, University of Georgia, Athens, United States

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.