Link
Publication
- Journal: Scientia Horticulturae, Vol. 369, 115283 (2026)
- Authors: Sejin Kim, Myeongsuk Kim, Mi Young Lim, Joohee Nam, Gyeong Lee Choi, Mi Young Roh, Dongpil Kim
- DOI: 10.1016/j.scienta.2026.115283
- Open Access: CC BY 4.0
Summary
Growers usually choose between high-pressure sodium (HPS) and LED supplemental lighting on lamp efficacy alone, yet HPS lamps also deliver radiant heat to the crop. We compared the two in three adjacent Venlo glasshouse compartments: an unlit control, HPS and LED. Both lamp types were set to the same light level (212 µmol m⁻² s⁻¹ at 1.5 m below the lamps) and the same switching schedule. High-wire cucumber was grown in all three, and we measured microclimate, growth, yield, photosynthetic traits and energy use.
Key Findings
- Yield: Both lit treatments raised marketable yield from mid-to-late February onward (control 3.2 kg, LED 5.1 kg, HPS 5.9 kg per plant). HPS outperformed LED mainly through fruit number (34.2 vs. 28.7 fruits per plant), and the cumulative yield gap was significant only for fruits harvested in March.
- Leaf temperature and photosynthesis: During the evening lighting hours, HPS leaves ran 1.3°C warmer than the air while LED leaves stayed at air temperature. Photosynthetic traits such as maximum electron transport rate and night-time Fv/Fm were the same under both lamps, so the HPS advantage came from canopy warming rather than higher photosynthetic capacity.
- Energy: LEDs used 44% less electricity for lighting, but radiant heat from HPS cut boiler heating by 40%. At Korean energy prices, HPS therefore had the lowest energy cost and CO₂ emissions per kilogram of fruit.
- Implication: In heated winter greenhouses, lamps should be chosen on the combined lighting and heating energy balance, not on lamp efficacy alone.