plant factories 2
In my previous
article on plant
factories, I showed
the productivity that might be
achieved using plant
factories compared with the
possible productivity achieved
by the best greenhouse growers. However, this cannot be
achieved without a sound
knowledge base on which to
make decisions. The first decision indoor growers must consider is what type of artificial light
they should use to grow their desired
crops. Currently, the choices are limited.
The first decision indoor
growers must consider is what
type of artificial light they should
use to grow their desired crops.”
Fluorescents
Fluorescent lamps are low-pressure mercury vapor lamps
that use fluorescence to produce visible light. They require
a ballast to regulate the current through the lamp, but
the lower energy cost usually offsets the higher initial cost.
The actual wavelengths of light produced depends on the
type of phosphor used to produce the fluorescence. In the
case of plants, the objective is to maximize the wavelengths
in the blue and red zone of the spectrum. Because they
contain mercury, many fluorescent lamps are classified as
hazardous waste and must be disposed of appropriately.
high-intensity discharge
Metal halide lamps, a type of high-intensity discharge lamps,
differ from the fluorescent types. Mainly, the different
wavelengths are produced by incorporating a suitable metal
halide into the vacuum of the lamp, ensuring a specific wavelength of light will be produced. The only HID lamp to really
catch on for horticultural purposes has been the high pressure sodium light (HPS). These have become the workhorses
in most greenhouses where artificial lighting is used.
102
Maximum Yield USA | January 2015