Internal tipburn of cabbage (Brassica oleracea var. capitata)

Internal tipburn of cabbage (Brassica oleracea var. capitata) is a serious quality defect. The discolouring and desiccation of inner head leaves may render whole yields useless. The disorder is regarded as a localized calcium deficiency. The deficiency is not caused by reduced calcium availability to the plant, but rather by calcium transport characteristics within the plant. Because of the absence of transpiration from the inner head leaves of the cabbage plant, calcium is transported to the meristematic tissues in the head mainly by root pressure flow or because of meristematic sink activity during the night. High growth rates are known to increase the incidence of internal tipburn. Probably because of the increased demand for calcium per unit of time, the result of disruption in the calcium transport to the head is more serious. Conditions of even transpiration between day and night, whether high or low, reduce root pressure flow to the head and thereby may induce development of internal tipburn. A combination of high growth rates and low root pressure flow during periods of prolonged dry, sunny weather with high transpiration rates during the day as well as during the night, may be especially important in inducing internal tipburn, because of insufficient calcium influx in the cabbage head under such conditions. As initiation of calcium deficiency in growing tissue is a subcellular process, visible symptoms of internal tipburn may be expressed only later. Growers are primarily advised to cultivate internal tipburn resistant cultivars. Recommendations to limit the occurrence of internal tipburn are formulated.