A model for leaf production and apex development in Calabrese

A single, temperature based model was developed, accounting for both leaf initiation and changes in the apex diameter of calabrese cv. Shogun associated with vernalization. The model was derived using data from an experiment in controlled environment cabinets, which had ten constant temperatures between 7.3 and 22.6 degrees C. It was tested on data from 20 field-grown crops of cvs Shogun and Corvet and 24 treatments of an experiment in growing rooms involving transfer of plants between different temperatures. The model predicted changes in both number of leaves and apex diameter of field plants accurately, except for some early values. In growth rooms, predictions were accurate for nearly all treatments. Simulation of leaf production and apex development for 100 d at temperatures from 0 to 35 degrees C, predicted that apex initiation would not occur at 0, 30 and 35 degrees C, and would take 96, 51, 36 and 64 d respectively at 5, 10, 15 and 20 degrees C.