Sulphur Plasma Lamps are the
new revolutionary light source with the highest effectivity
and a true full spectrum similar to that of sunlight.
The sulphur plasma consists mainly of dimer
molecules (S2), which generate the light through molecular
Because this, instead of atomic emission,
is the mechanism of light generation, the emission spectrum
is continuous throughout the visible spectrum.
The lamp's output is low in infrared energy,
and less than 1% is ultraviolet light. As much as 75% of the
emitted radiation is in the visible spectrum, far more than
other types of lamps.
The visible light output mimics sunlight
better than any other artificial light source, and the lack
of harmful ultraviolet radiation can be especially beneficial
to museums and displays of art.
The spectral output peaks at 520 nanometres
and the correlated colour temperature (CCT) is approximately
6000 kelvins with a colour rendering index (CRI) of 86. The
lamp can be dimmed to 15% without affecting the light quality,
and light output remains constant over the life of the bulb.
|An artificial solar
spectrum substantially alters plant development compared with
usual climate room irradiance spectra
W. Hogewoning*, Peter Douwstra, Govert Trouwborst, Wim van
Ieperen and Jeremy Harbinson
Wageningen University, Department
of Plant Sciences, Horticultural Supply Chains Group, Wageningen,
Plant responses to the light spectrum under which plants
are grown affect their developmental characteristics in a
complicated manner. Lamps widely used to provide growth irradiance
emit spectra which are very different from natural daylight
spectra. Whereas specific responses of plants to a spectrum
differing from natural daylight may sometimes be predictable,
the overall plant response is generally difficult to predict
due to the complicated interaction of the many different responses.
So far studies on plant responses to spectra either use no
daylight control or, if a natural daylight control is used,
it will fluctuate in intensity and spectrum. An artificial
solar (AS) spectrum which closely resembles a sunlight spectrum
has been engineered, and growth, morphogenesis, and photosynthetic
characteristics of cucumber plants grown for 13 d under this
spectrum have been compared with their performance under fluorescent
tubes (FTs) and a high pressure sodium lamp (HPS).
The total dry weight of the AS-grown plants was 2.3 and 1.6
times greater than that of the FT and HPS plants, respectively,
and the height of the AS plants was 4–5 times greater.
This striking difference appeared to be related to a more
efficient light interception by the AS plants, characterized
by longer petioles, a greater leaf unfolding rate, and a lower
investment in leaf mass relative to leaf area. Photosynthesis
per leaf area was not greater for the AS plants. The extreme
differences in plant response to the AS spectrum compared
with the widely used protected cultivation light sources tested
highlights the importance of a more natural spectrum, such
as the AS spectrum, if the aim is to produce plants representative
of field conditions.
Key words: Artificial solar spectrum, blue light, growth
rate, leaf mass per area (LMA), light absorptance, light interception,
light quality, photomorphogenesis, photosynthetic capacity
Received 20 October 2009; Revised 5 January 2010 Accepted
8 January 2010
GROWTH UNDER MEATAL
HALIDE & MICROWAVE POWERED SULPHUR PLASMA LAMPS
Microwave Powered Sulfur (MPS)
Appearance of 'Poinsett' cucumber
plants grown for 14 days in a growth chamber under six
400 W metal halide (MH) lamps and under a single 1000
W microwave powered sulphur plasma lamp (MPS).
Note space between MH grown plants and
the absence of space between MPS grown plants and the
fact that pot labels are still visible among the MH grown
plants but not the MPS grown plants.
27. 81-92, 1998
OF PHOTOSYNTHETIC PHOTON FLUX AND GROWTH OF 'POINSETT'
CUCUMBER PLANTS UNDER METAL HALIDE AND MICROWAVE-POWERED
D. T. KRIZEKR~., M . MIRECKaI nd W. A.
Climate Stress Laboratory, Natural Resources
Institute, Agricultural Research Service, U.S. Department
of Agriculture, Beltsville, MD 20705-2350, USA
(Received September 11, 1998; Accepted
October 1, 1998)
KRIZEKD, . T.. MIRECKIR. . M. and BAILEYW,
. A. Uniformity of photosynthetic photon flux and growth
of 'Poinsett' cucumber plants under metal halide and
microwavepowered sulfur lamps. BIOTRONICS 27, 81-92.
The uniformity of photosynthetic photon flux (PPF) and
vegetative growth of Cucumis sativus L. ('Poinsett' cucumber)
were examined using growth chambers equipped with either
six 400 W metal halide (MH) lamps or with a single 1000
W microwave -powered sulfur (MPS) (LIGHTDRIVETM 1000)
lamp mounted on a polished stainless steel reflector
with secondary screening for microwave protection.
PPF levels in each growth chamber were
set initially at 500pmol m-2 s-I. Pots were placed at
equal distance from one another in ten columns of six
rows each (n=60). Growth measurements were only taken
on the center six columns of plants (n=36). The uniformity
of PPF was greater in the MPS than in the MH chamber
for both the 36 and the 60 pot arrangement. However,
growth measurements showed similar variance in the MH
as in the MPS chamber. Plants grown for 14 days under
MPS lamps had significantly greater growth than those
under MH lamps. Petiole length, total stem length, and
leaf enlargement were 90%, 44%. and 34% greater, respectively.
in plants grown under MPS lamps than under MH lamps.
Similar differences were obtained in biomass; dry weights
of tops and roots of MPS grown plants were 28% and 36%,
greater, respectively, than those of MH grown plants.
These findings demonstrate the potential of using sulfur
lamps for accelerating seedling production under controlled
environments and validate the concept that sulfur lamps
have a better spectral quality for plant growth than
metal halide lamps. These results should be of interest
to growers and researchers involved in protected cultivation.
The LIGHTDRIVETM 1000 sulfur lamp should also provide
a useful tool for studying the photocontrol of shoot