Environmental control of flowering time in Antirrhinum majus

The effect of different environmental conditions on flowering time and the number of leaves produced before the first flower is formed has been investigated in Antirrhinum majus L. The effect of light quality has been tested by decreasing the red/far-red ratio, generally resulting in a reduced flowering time and leaf number. Furthermore, it could be shown that photoperiod, temperature and light intensity are inversely correlated with flowering time and leaf number. However, lowering the temperature from 15 to 12 degrees C resulted in a reduction of flowering time. This observation shows that Antirrhinum can be vernalised. Using defined combinations of the four environmental factors we have been able to reduce flowering time to only 42 days or to delay flowering for at least 2 years. The results obtained allow an optimisation of the screening conditions for identifying flowering time mutants in Antirrhinum.