have 4–6 hr in darkness during a 24-hr cycle. Also, for any given daily integrated PPF, a lower average
instantaneous PPF is preferable to decrease the crop’s light compensation point. The combination of a
longer photoperiod and a lower average instantaneous PPF, for any given daily integrated PPF, consti-
tutes the ideal scenario for lowering maintenance respiration and improving the crop’s growth or yield.
Because proper design of a composite lighting profile could result in significant crop growth for a
given total integrated PPF, an important implication of composite lighting is that it could potentially cut
down significantly the electrical power required to achieve a given desired level of crop biomass. It is en-
tirely probable that employing an appropriate composite lighting profile could obviate the delivery of ad-
ditional moles of photons to a given crop to increase its growth or yield because composite lighting, rel-
ative to certain conventional lighting profiles, could increase crop growth or yield without increasing the
total integrated PPF. The capacity of composite lighting to conserve electrical power by its ability to op-
timize crop yield requires further investigation. Its benefits would be of significant importance not only
in terrestrial greenhouse and growth-chamber applications but also in extraterrestrial advanced life sup-
port systems for the human exploration and development of space.
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