[Difference in photoperiodic sensitivity of the upper and lower side of leaves of Kalanchoe blossfeldiana].

The short-day plant Kalanchoe blossfeldiana was grown on short photoperiods and was given supplementary light of low intensity (4-7 lux). If the supplementary light was supplied to the upper sides of the leaves flowering was strongly inhibited. Irradiation of the lower sides was much less effective.