Department of Plant Sciences

It is not known how cauliflower (Brassica oleracea var. botrytis), a cool-weather, high nutritional-value vegetable, achieves its high nutritional levels, the hearty structure and fresh appearance. A study of cauliflower plant and nitrogen nutrition relations was conducted in a commercial production field in Annapolis Valley, Nova Scotia. The objectives were to determine the effects of nitrogen nutrition on cauliflower plant development and to quantify cauliflower plant N uptake ability among different varieties. The treatments consisted of three cauliflower varieties (‘Minuteman’, ‘Sevilla’ and ‘Whistler’) and three post-transplanting rates of N (0, 45 and 90 kg ha-1), arranged in a split-block design in the field. Results showed that the N uptake ability of cauliflower plants varied between 6.2 and 9.0 g plant-1, depending on varieties. The cauliflower varieties ‘Sevilla’ and ‘Minuteman’ had a significantly higher ability of N uptake than the cultivar ‘Whistler’ (P < 0.05). All three varieties responded significantly to the reduced post-transplanting input (45 kg N ha-1). There was a significant correlation between cauliflower head yield and whole plant N uptake (R2 = 0.64, P < 0.05). It was suggested that increasing N assimilation in whole plant could stimulate cauliflower head development, which could also lead to a reduction of 50% post-transplanting inputs. Future studies will be focused on quantification and regulation of N temporal reserves in leaves that could enhance N transfer to sinks (heads) and that could promote cauliflower plant head development.