The data re what constitutes the perfect light intensity and duration is not readily available because the number of variables involved (things like light quality, duration, intensity, color temperature, air quality, CO2 availability, et al) all have an impact on how much usable light there is and/or how much can be turned into food. A precise answer would require that all variables be taken into account, and that would be difficult enough in a controlled environment, never mind our backyards.
Al
