Spectral Distribution of Dimmed HID Lamps in a Plant Growth Facility
- G. E. Bingham and
- P. I. Coyne
A commercial dimming ballast system for high intensity discharge (HID) lamps has been tested for use in plant growth chambers. The dimming ballast system can be controlled either manually at the dimming panel or by a d.c. voltage from a programmer or computer. Using the dimming system, photosynthetically active radiation can be continuously varied from about 200 to about 2000 µE m−2s−1. This paper shows the effects of dimming on the spectral intensity (400 to 750 nm) of three types of HID lamps measured individually and in combination to achieve a better spectral mix. The lamps used in this study were 400 w metal halide, mercury vapor and high pressure sodium.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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