Link
Publication
- Journal: Horticulture, Environment, and Biotechnology (2026, Online First)
- Authors: Minhee Han, Jeongho Kim, Jiwoong Bang, Jaehan Lee, Jin Hyun Kim, Dongpil Kim
- DOI: 10.1007/s13580-026-00860-w
Summary
This study asked whether the light spectrum used to raise cucumber transplants in a vertical farm still matters once the plants move to a sunlit greenhouse. Seedlings spent 28 days under one of three LED spectra at a PPFD of 400 µmol m⁻² s⁻¹ and a 16 h photoperiod: a red–blue reference (80R20B), a high-blue spectrum (50R50B), and a spectrum in which part of the blue was replaced by far-red (80R10B10FR). They were then grown for 42 days in a Venlo glasshouse in Haman, Korea, while we tracked morphology, flower position, yield, photosynthesis and chlorophyll fluorescence.
Key Findings
- Far-red substitution (80R10B10FR): 42 days after transplanting, plants still had 19% more shoot dry weight, 8% more leaves and 39% more leaf area than the reference. Female flowering was delayed, though: lower nodes carried mostly male flowers and the first female flower appeared higher on the stem. Early cumulative marketable yield matched the reference (about 790 g per plant).
- High blue (50R50B): Seedlings were compact but never caught up after transplanting, ending with 18% less shoot dry weight and 14% lower marketable yield.
- Photosynthesis: Light-response parameters such as maximum assimilation rate did not differ among treatments five days after transplanting. The pre-transplant differences in Fv/Fm disappeared soon after the plants moved to natural light.
- Implication: The 80R20B reference gave the best balance of flowering time, vegetative growth and early yield. Seedling light recipes should be judged by post-transplant productivity as well as by transplant quality.