A MODEL OF THE EFFECTS OF TEMPERATURE ON THE GROWTH AND DEVELOPMENT OF CAULIFLOWER (BRASSICA-OLERACEA L BOTRYTIS)

A model is described which predicts the time to curd initiation, and the duration or rate of curd growth of cauliflowers. The model was calibrated with data collected from commercial crops grown during the 1989, 1990 and 1991 seasons. The reciprocal of the time from planting to curd initiation, for cultivar 'Revito', was linearly related to effective temperature determined with an optimum of 14-degrees-C. Curd initiation occurred after the accumulation of 296 degree-days above a base temperature of 2.8-degrees-C. Curd growth of three cultivars, 'Jubro', 'Revito' and 'White Fox' was described by a simple model which incorporated two terms; one describing a linear ontogenetic decline in potential relative curd growth rate (RGR) with thermal time and the second which described the instantaneous effects of temperature on RGR. The optimum temperatures for curd growth of cultivars 'Jubro', 'Revito' and 'White Fox' were 16-degrees-C, 25-degrees-C and 21-degrees-C, respectively. The model accounted for 37.4%, 40.4% and 95.8% of the variance in curd growth of the varieties 'Jubro', 'Revito' and 'White Fox', respectively. The curd initiation and curd growth components of the model accurately described several independent data sets. The model can be used for both crop scheduling and for predictions of crop maturity.