Endogenous Cytokinins in Solanum tuberosum as Influenced by Photoperiod and Temperature

Using the cucumber cotyledon bioassay, in combination with paper and column chromatographic techniques, 4 compounds exhibiting cytokinin activity were detected in extracts of Katahdin potato plant tissues. Two of these compounds were significantly higher in plants grown under inducing conditions (26°C day and 12°C night with an 8-h photoperiod) than those grown under non-inducing conditions (28°C day and 25°C night with a 16-h photoperiod). One compound increased 10-fold in above-ground tissue after only 2 Inductive cycles. Both compounds reached their maximum values in below-ground tissue after 6 days under inducing conditions, with tuber initiation observed after 8 to 10 days.