THE INFLUENCE OF FIELD ENVIRONMENTAL-CONDITIONS ON CALABRESE GROWTH AND DEVELOPMENT

Experiments studying calabrese growth and development were conducted in four years (1986-1989), using five cultivars and a range of transplanting dates each year. Crop growth was monitored by weekly sampling and dissection and the data are used to provide information to improve crop planning and prediction. The relationship between the time from transplanting to maturity and the date of transplanting was best described by fitting parallel quadratic curves for each cultivar. These accounted for 76% of the variance in the time from transplanting to maturity and could be used to plan continuity schedules. However, the magnitude of the variation about the fitted lines due to the crops' responses to weather suggested that in practice continuity would be difficult to achieve. A logistic relationship for all cultivars between the logarithm of head diameter and accumulated effective day-degrees from head initiation accounted for 96% of the variation in head diameter and in individual cultivars up to 97% of the variation in head diameter. It is suggested that such relationships could be used to predict when heads of any required size will be produced.