Investigating use of blue, red, and far-red light from light-emitting diodes to regulate flowering of photoperiodic ornamental crops

by Meng, Qingwu, M.S., MICHIGAN STATE UNIVERSITY, 2014, 134 pages; 1560317


When the natural photoperiod is short, lighting during the middle of the night (night interruption, NI) can promote flowering of long-day plants (LDPs) and inhibit flowering of short-day plants (SDPs). Unlike some conventional lamps, light-emitting diodes (LEDs) are energy efficient, durable, and controllable. We coordinated a trial with five commercial greenhouses to compare the efficacy of 4-hour NI lighting from red (R; 600 to 700 nm)+white (W)+far-red (FR; 700 to 800 nm) LEDs and conventional lamps to regulate flowering of eight photoperiodic ornamental crops. In most instances, the R+W+FR LEDs were as effective at controlling flowering as conventional lamps. Therefore, these LEDs specifically developed for flowering applications emit an effective spectrum and can replace less energy-efficient conventional lamps. In another experiment, we investigated the role of low-intensity (1 to 2 μmol·m-2·s -1) blue (B; 400 to 500 nm) light in regulating flowering of four LDPs and five SDPs. Low-intensity B light, alone and when added to R and FR light, did not influence flowering or plant morphology. In a third experiment, we determined whether B light at higher intensities (15 and 30 μmol·m -2·s-1) controlled flowering of five LDPs and one SDP. B light at 30 μmol·m-2·s-1 created long days in all crops as effectively as low-intensity R+W+FR light. However, the addition of B light to R+W+FR light did not further accelerate flowering. Therefore, the effectiveness of B light in NI lighting apparently depends on some threshold intensity and does not modify the response to R+W+FR light. The promotion of flowering from a higher irradiance of B light could be mediated by cryptochromes, phytochromes, or both.

AdviserErik S. Runkle
Source TypeThesis
Publication Number1560317

About ProQuest Dissertations & Theses
With nearly 4 million records, the ProQuest Dissertations & Theses (PQDT) Global database is the most comprehensive collection of dissertations and theses in the world. It is the database of record for graduate research.

PQDT Global combines content from a range of the world's premier universities - from the Ivy League to the Russell Group. Of the nearly 4 million graduate works included in the database, ProQuest offers more than 2.5 million in full text formats. Of those, over 1.7 million are available in PDF format. More than 90,000 dissertations and theses are added to the database each year.

If you have questions, please feel free to visit the ProQuest Web site - - or contact ProQuest Support.