FACTORS AFFECTING FLOWERING IN SENECIO CRUENTUS D.C.
The cineraria requires a period of low temperature for the formation of flowerbuds. Post (1) stated already in 1942 that the critical temperature for flowerbud formation is about 15°C. During the last years new cultivars have been developed and the plant has gained new popularity. Experiments have therefore been carried out in order to find 1) the critical temperature for flowerbud formation in the new cultivars, 2) for how long the plants must be subjected to inductive temperature levels and 3) what are optimum temperatures for flower development.
In his experiments with cineraria, Post (1) found that long days given after the formation of the buds hastened flowering compared with short days. The elongation of the stem was also favoured by the long day treatment, and the plants became too tall. A long day treatment could therefore not be recommended. Wasscher (2) has shown that the cineraria plants do not elongate that much if fluorescent tubes are used instead of incandescent lamps during the long day treatment. Long day treatment, however, has not been used to any large extent by cineraria growers. A few experiments have therefore been carried out in order to find the day-length response of some common cineraria cultivars.