PHOTOPERIODIC CONTROL OF PHENOLIC METABOLISM IN KALACHOE-BLOSSFELDIANA

When grown in conditions of long day length, the leaves of Kalanchoe blossfeldiana contain high levels of soluble phenolic compounds, mainly present as tannins. A decreasing concentration gradient is observed in the leaves from the apex to the base. When transferred to short day conditions, the ability of leaves of the same physiological age to accumulate phenolics decreases with time. The very low phenolic content after 25 short days indicates pronounced changes in the metabolism of the plant induced by new photoperiodic conditions. Moreover, during development in short days the amount of tannins per leaf reaches a maximum then decreases suggesting an over-polymerization or even a degradation of the substances. A similar lag time is required for the depressing effect of short days on phenolies and for their stimulating effect on CAM. © 1979.