Changes in some nutrient contents of broccoli (Brassica oleracea L. var. italica Plenk) inflorescences affected by the brown bud disorder

Abstract

The incidence of brown bud disorder in broccoli is quite common in the Spanish Mediterranean region during early autumn and late spring. This disorder affects the quality of heads and shoots, and more important reduces its value as a fresh-market export.

In previous studies we concluded that this disorder is related to high temperatures during inflorescence formation and that there is a great variation in the degree of susceptibility between cultivars. In some cases calcium chloride foliar applications reduced the incidence of this disorder. Potassium also seems to be involved in some way.

We studied the Ca, K and Mg content of healthy and affected heads using an atomic absorption spectrophotometer, in two experiments carried out during 1992 and 1993, utilizing different fertilizer treatments and the cultivars Coaster, Shogun and Skiff, in order to study the nutritional basis of this physiopathy.

Ca levels in heads affected by brown bud disorder were always higher than in healthy ones. This does not agree with the responses to Ca applications mentioned to above. In the course of the experiment, and in both years, K and Mg content varied between cultivars. The ratio K/(Ca+Mg) was higher in the healthy inflorescences, with respect to affected ones.