Growth of Potatoes for CELSS p. 34 (1994)
T. W. Tibbitts

DURATION AND INTENSITY

Both photoperiod and light intensity have major controlling effects on productivity of potatoes. It has long been accepted and demonstrated that short photoperiods, e.g. less than 12 hours, encourage tuberization of potatoes (Ewing and Struik, 1992; Gregory, 1965), and it is also recognized that low light levels produce more photosynthesis per unit of light than high light levels (Bodlaender, 1963). Thus, in an attempt to reduce light intensity without reducing the total amount of light received by plants, a significant effort was undertaken to utilize continuous lighting for potatoes. This approach has the added advantage to gain efficiency in electrical use and also hopefully to reduce the quantity of lighting that would have to be installed in a CELSS. Early in this research it was found that potatoes, or at least some cultivars, would tolerate and develop a high production under continuous light. As the studies progressed, it was found that tuberization was initiated quite rapidly under continuous light if light was maintained at a high enough level. The work has documented that long light periods encourage shoot growth, but if enough light is provided with long light periods, tuberization will occur at a high rate in essentially the same period of time as under short light periods.

Continuous lighting biblio