Vol. 73 No: 5

Title:
Leaf Production and Curd Initiation of Winter Cauliflower in Response to Temperature

Authors:
D.C.E. WURR and JANE R. FELLOWS

pp: 691-697

Abstract:
In experiments in 1994 and 1995 a range of transplanting dates and thermal crop covering treatments were used to produce different environmental conditions for the growth of two Roscoff cauliflower selections ‘December/January’ and ‘March’. In 1994 non-covered plants of ‘March’ initiated on average 19 d later and with 19 leaves more than ‘December/January’. In the two seasons, covering the crops gave delays in curd initiation of up to 93 d, depending on planting date, and increased the number of leaves produced by up to 50 compared with non-covered crops. Leaf production was best described by an accumulated effective day-degree scale using day-degrees <17°C for ‘December/January’ and day-degrees <16°C for ‘March’. This shows that both light and temperature are concerned with controlling leaf production. During the juvenile phase of growth, apex diameters expanded linearly with temperature up to a diameter of about 0.2 mm. After this there was a different response to temperature suggesting that a phase change had occurred at an apex diameter of 0 2 mm. When this occurred numbers of leaves ranged from 23 to 28. Vernalization appeared to occur most rapidly in ‘December/January’ between 12 and 16°C with an optimum at about 14°C while in ‘March’ the optimum appeared to be slightly lower than this. Any increase in time spent at temperatures in excess of 16°C delayed curd initiation.

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