Studies on Dark Fixation of Carbon Dioxide in Kalanchoë: II. Effect of Interaction of Photoperiodic Induction with Water Stress and Growth Retardants

Abstract

In Kalanchoe blossfeldiana von Poellnitz cv. Tom Thumb and cv. Feuer Blute interaction of C02 fixation with photoperiodic induction and water stress was examined. It was found that Tom Thumb raised in dilute culture solution and kept in photoinductive cycles (8 h light and 16 h dark) flowered but failed to show a net dark C02 fixation. A net dark fixation was observed when the concentration of the culture solution was increased or plants were sprayed with 300 or 750 mg 1_1 CCC or 300 or 2000 mg l-1 B-9. In a non-inductive photoperiod no net dark fixation was observed with these treatments although there was a tendency for dark fixation to increase. Feuer Blute did not flower in inductive photoperiods when kept in half strength solution. It is suggested that in Tom Thumb both photoperiodic induction and water stress are required for initiation of net C02 dark fixation. In Feuer Blute where CAM is occurring normally photo-induction is sufficient to induce flowering. In half strength solution C02 dark fixation is disturbed and floral induction also does not occur.