Effects of supplemental lighting and temperature on summer production of tomato in Norway

Addition of artificial lighting to the natural light conditions in greenhouse vegetable production along the coastline of Norway has resulted in the highest yields of greenhouse vegetables worldwide.
Even during the summertime, abundance of cloudy days necessitate the use of supplemental light to reach optimal light levels for tomato production.
Hydroelectric energy is used to provide energy for high pressure sodium (HPS) lamps; however, HPS lamps contribute significant with radiant heat energy.
Increased heat energy due to high levels of installed power of HPS lamps has adverse effects on evaporation and plant performance and increases the need for ventilation, with a subsequent loss of energy and CO₂. One alternative to HPS lamps is light emitting diodes (LED), which produce less heat radiation energy.
This experiment was designed to quantify the effects of increased light intensities provided by supplemental HPS and LED lighting on the production and energy use in greenhouse tomatoes in Norway.
Increased light intensity increases the optimal temperature for plant growth, thereby necessitating optimisation of the greenhouse ventilation temperature.
This study investigated three different greenhouse lighting/ventilation strategies: 1) HPS lighting and ventilation temperatures of 22/18°C (day/night) (control), 2) HPS lighting and additional LED inter-lighting with ventilation temperatures of 22/18°C (day/night), and 3) HPS lighting and additional LED inter-lighting with ventilation temperatures of 27/20°C (day/night). The addition of LED inter-lighting (production strategy 2) increased the need for ventilation when compared with HPS lighting alone.
Allowing a higher ventilation temperature (production strategy 3) resulted in a higher greenhouse temperature but not in a higher plant development rate.
Production strategy 3 led to a considerably lower dry matter distribution to the fruits when compared to the other strategies, indicating sink limitation.
In order to profit from additional LED inter-lighting with respect to fruit yield and energy savings, an increase in ventilation temperature of 1-2°C is suggested.

International Symposium on Advanced Technologies and Management for Innovative Greenhouses: GreenSys2019

M.J. Verheul, H.F.R. Maessen, A. Panosyan, M. Naseer, M. Paponov, I.A. Paponov

greenhouse production, tomato, artificial light, CO₂, dry matter accumulation, yield, photosynthesis, dry matter distribution, greenhouse climate, energy consumption

https://doi.org/10.17660/ActaHortic.2020.1296.89