RELATIONSHIPS AMONG CO2 DARK-FIXATION, SUCCULENCE, FLOWERING, AND ORGANIC ACID FORMATION IN KALANCHOE BLOSSFELDIANA VARIETY TOM THUMB

Kalanchoe blossfeldiana variety Tom Thumb was treated photoperiodically in regular and CO2-free air and examined at two widely separated time intervals for interrelationships among flowering, succulence, capacity for CO2 dark-fixation, and organic acid formation. These processes and leaf thickening are all under photoperiodic control and increase with increasing numbers of short-day treatments. They also occur in a CO2-free atmosphere on 9-hour photoperiods although CO2 dark-fixation and organic acid formation are limited to the low level of the long-day treated plants at 5 weeks' time. Only CO2 dark-fixation and organic acid formation appear to be interrelated and apparently utilize respiratory CO2 if treated in a CO2-free atmosphere. This capacity to use respiratory CO2 increases with maturity of the plants. Flowering does not control the development of succulence, organic acid formation, or the capacity for CO2 dark-fixation. Likewise, capacity for dark-fixation and organic acid formation do not control flowering and can occur in vegetative Tom Thumb plants that do not exhibit appreciable succulence.