Supplemental radiation (SR), traditionally provided by high-pressure sodium (HPS) lamps, is recommended for greenhouse production of seedlings during radiation-limiting conditions. Light-emitting diodes (LEDs) have emerged as an appealing alternative to HPS lamps primarily because they can provide SR at improved energy efficiencies, they have longer fixture lifetimes, and the radiation spectrum can be tailored to potentially manipulate plant morphology by targeting radiation absorption of specific photoreceptors.
Researchers grew seedlings of three annual bedding plants and two vegetable transplants in greenhouses at 20 °C under a 16-h photoperiod under six SR treatments: five that delivered a photosynthetic photon flux density (PPFD) of 90 μmol·m−2·s–1 from HPS lamps (HPS90) or LEDs [four treatments composed of blue (B; 400–500 nm), red (R; 600–700 nm), far red (FR; 700–800 nm), and/or white LEDs] and one that delivered 10 μmol·m−2·s–1 from HPS (HPS10) lamps as a control with matching photoperiod.
The LED treatments, defined by the percentages of B, green (G; 500–600 nm), and R radiation, were B10R90, B45R55, B10G5R85, and B12G20R68 + FR (FR at 12 μmol·m−2·s–1). At transplant, leaf area and seedling height were similar among 90 μmol·m−2·s–1 treatments in all species except snapdragon (Antirrhinum majus), in which seedlings grown under B12G20R68 + FR had 62% greater leaf area than those grown under B45R55 and were 47%, 18%, 38%, and 62% taller than those grown under HPS90, B10R90, B10G5R85, and B45R55, respectively.
After transplant and finishing under the same SR treatments, snapdragon flowered on average 7 days earlier under the B12G20R68 + FR treatment than the other LED treatments, whereas geranium (Pelargonium ×hortorum) grown under B45R55 and B12G20R68 + FR flowered 7 to 9 days earlier than those under the B10G5R85 and B10R90 treatments. Seedlings of each species grown under the HPS10 treatment accumulated less dry weight and took longer to flower compared with seedlings under the other SR treatments.
The study authors conclude that radiation quality of SR has relatively little effect on seedling growth and subsequent flowering although in some crops, flowering may be earlier when SR includes FR radiation.
Access the full study at HortScience.
Announcements
Vacancies
- Head Grower Strawberries, Australia
- Growing Manager for Hydroponic strawberry producer
- Farm Manager Costa Rica
- Regional Sales Manager Fresh Produce
- Head Grower Strawberries, Norway
- Export Trade Manager
- Business Developer - Northern Europe
- Orchard Sector Manager
- Grower
- International Citrus Account Manager
Spectral effects of supplemental greenhouse radiation
Publication date:
Receive the daily newsletter in your email for free | Click here
Other news in this sector:
- 2023-09-26 “With greenhouse cucumbers, it’s tricky to get the water balance right"
- 2023-09-26 Israeli company introduces new tech as bees struggle to pollinate
- 2023-09-26 "The investment in the vertical farming area is really growing, even when so many people will think differently"
- 2023-09-25 Fostering beneficial fungi in crops from recent PhD research
- 2023-09-21 Auction with various applications for the fruit and vegetables industry
- 2023-09-21 Denmark: Seasony obtains grant to create image recognition algorithms
- 2023-09-21 SaniTomato preserves the properties and freshness of tomatoes for longer
- 2023-09-19 Growing interest and attention to regenerative agriculture practices are driving new research
- 2023-09-19 Why crops grow better with more light?
- 2023-09-19 New Crop-Scanner offers improved scouting and advice
- 2023-09-19 Modeling: a tool for taking the guesswork out of growing
- 2023-09-18 New harvesters for produce destined for the fresh-cut industry
- 2023-09-18 New unit allows on-site carbon capture and reutilization for CEA grower
- 2023-09-18 Sensor development: far-red light for optimal growth
- 2023-09-15 "Growers want to see where limits lie in screen strategies"
- 2023-09-15 Jamaica: Growers encouraged to consider aquaponics
- 2023-09-15 Time for the big clean-up, time for the crop rotation
- 2023-09-15 "How IoT is shaping the future of agriculture"
- 2023-09-14 "The TomSystem can help prevent virus transmission in the greenhouse"
- 2023-09-14 Tomato grower invests in nanobubbles: "Nothing was allowed to go wrong anymore"
