Initiation of early summer cauliflowers in response to temperature

SummaryTwo experiments were conducted with the early summer cauliflower cvs Perfection and Gypsy. The first was in controlled environment cabinets with nine temperatures ranging from 6.3 to 22.88C. The second was in the field with three planting dates and plants grown with and without fleece cover. The experiment in controlled environments enabled a model to be developed which predicted changes in apex development through both the juvenile and curd induction phases. Both the end of juvenility and curd initiation were defined in terms of apex diameter. For cv. Perfection these were respectively 0.25 and 0.55.mm while with cv. Gypsy they were respectively 0.27 and 0.51.mm. The number of leaves produced at the end of juvenility was very different in the two experiments. When applied to the field temperatures from planting, the model predicted the end of juvenility early and therefore estimates of curd initiation were inaccurate. However, when the model was started, with the recorded apex diameter exceeding t...