Agriculture Reference
In-Depth Information
Fig. 10.4
Application of
LED-interlighting in tomato
plants by an experimental
trial at the Horticultural
Center Straelen, Agricultural
Chamber of North Rhine-
Westphalia in Germany.
(Source: Gruda 2013, private
collection.)
plants. In addition, interlighting increased first class yield and decreased the unmar-
ketable yield of cucumbers, both in weight and fruit number. Besides interlighting
per se, the higher proportion of interlight tended to further improve the fruit quality
as well as fruit skin chlorophyll concentration (Heuvelink et al.
2006
; Hovi-Pe-
kkanen and Tahvonen
2008
).
The addition of SAL, with no adjustments in the climate set points and crop man-
agement, may result in improved vegetative growth but little or no yield improve-
ment. The adjustments in temperature, plant density and other factors are needed, in
order to optimally transfer SAL into production (Heuvelink et al.
2006
).
Future applications could be the development of light-emitting diode (LED)
lamps which has several unique advantages over existing horticultural lighting such
as being small in size, increased longevity and low heat emission even at very high
light intensity levels. In addition LED lamps have the ability to control spectral
composition, given the opportunity to select the most favorable light spectrum for
photosynthesis (Fig.
10.4
) (Morrow
2008
; Paradiso et al.
2011
).
Martineau et al. (
2012
) compared LED and HPS lighting technologies for sup-
plementing greenhouse lighting and found on average, that HPS and LED light
treatments produced similar shoot biomass of head lettuce (
Lactuca sativa
var.
cap-
itata
), with the LED lamps providing approximately only half the amount of supple-
mental light compared with the HPS lamps during a 4 week experimental treatment.
In addition no significant differences were found in concentrations of β-carotene,
chlorophyll a, chlorophyll b, neoxanthin, lutein, and antheraxanthin among the light
treatments. According to Morrow (
2008
), the LED array provides three times more
light output for the same Wattage of input power on an equivalent area basis and
can be easily integrated into digital control systems, facilitating special lighting
programs such as “daily light integral” lighting and sunrise and sunset simulations.
In addition LEDs could be used at different radiation angles for different culti-
vation types and development stages and provided the capability of true spectral
composition control, allowed wavelengths to be matched to plant photoreceptors to
provide more optimal production, and influenced plant morphology and composi-
tion (Morrow
2008
). With most plants reaching a major peak in the red region and
