THE EFFECT OF TEMPERATURE AND SHADE ON CURD INITIATION IN TEMPERATE AND TROPICAL CAULIFLOWER

Plants of both varieties were grown in 6 different temperature compartments averaging 11, 13.5, 19.5, 22.5, 25 and 29 °C. In each temperature compartment, 3 levels of shade were given to the plants; no shade, 40% shade and 60% shade. Results showed that curd initiation was influenced by both temperature and shade. Curd initiation for both varieties occurred earliest at 13.5°C and was delayed by both cooler and warmer temperatures. Initiation was more rapid at all temperatures for the local Mauritian variety B24/94 as compared to cv. Revito. At all temperatures where curds were initiated, the variety Revito was found to be more responsive to the effect of shade than B24/94. A simple relationship constructed for the local Mauritian variety, showed the rate of progress to curd initiation was linearly related to both effective temperature (with an optimum of 14 °C) and light integral (r² = 0.98, 10 df). An increase in temperature and shade caused an increase in the number of leaves formed below the curd.

Results are discussed in terms of the effects of environment on the initiation of temperate and tropical cauliflower. It is suggested that tropical varieties may be adapted because they initiate in a shorter period of time than temperate cultivars, and not due to changes in the optimum temperature for curd initiation.

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