A thermal time model of post-initiation flower development in the shade plant, cineraria

Effects of temperature on flower development in cineraria cv. Cindy Blue we re studied in controlled environment rooms and in glasshouses. The base, op timum and maximum temperatures respectively for progress to macroscopic flo wer appearance after flower initiation respectively were 1.6 degrees C, 19. 3 degrees C and 39.8 degrees C. From these cardinal temperatures, a thermal time requirement for flower appearance after flower initiation was calcula ted to be 130 degrees Cd. The base, optimum and maximum temperatures for pr ogress to anthesis after flower initiation were respectively 1.7 degrees C, 22.3 degrees C and 37.1 degrees C and from these values, the thermal time required to reach anthesis after flower initiation was calculated to be 555 degrees Cd. No significant difference was demonstrated between thermal tim es for flower development in plants grown in controlled environment growth rooms or under glasshouse conditions where irradiance and photoperiod varie d markedly.