D.C.E. Wurr
It is a common occurrence for several cauliflower crops within a sequence of transplantings to mature at the same time, causing a subsequent gap in the continuity programme. Current planning techniques for crop continuity are based on long-term average weather. In practice this results in considerable variation from crop to crop in the time from transplanting to maturity because the development of the crop is temperature-related. There is little scope for changing agronomic techniques to overcome these fluctuations in supply but it is possible to predict when individual crops will mature and thus aid their marketing.

Research to develop a prediction technique for the time of cauliflower maturity has concentrated on the period from curd initiation onwards and detailed measurements on 84 crops have shown that the growth of curds can be related to accumulated day-degrees from initiation. A single line accounted for 96.5% of the variance in mean curd diameter. In practice the prediction technique involves taking a representative sample of plants from the crop once the curd diameter is at least 10 mm, removing the leaves and measuring the diameter of the curd. These data are fed into a computer model together with the date of sampling, and the target curd size for maturity. The model then calculates the day-degree requirement for a curd to grow from the current size to the target size and, using average temperature data, converts this into a predicted harvest date. It can also use current temperature data to update an earlier prediction made using average data. The model predicts when 50% of the crop will reach the target size and also gives predicted dates for when other proportions of the crop, for example 10 and 90%, will reach that size, thus giving an estimate of the spread of maturity. It is currently being used to provide commercial predictions of the time of curd maturity in the UK.

Wurr, D.C.E. (1990). PREDICTION OF THE TIME OF MATURITY IN CAULIFLOWERS. Acta Hortic. 267, 387-394
DOI: 10.17660/ActaHortic.1990.267.45

Acta Horticulturae