The effect of nitrogen, harvest date and bud size on postharvest yellowing of buds of an early and a late cultivar of Brussels sprout (Brassica oleracea var. gemmifera)

Abstract

SummaryA study was made of the effect of nitrogen application shortly before harvest on postharvest yellowing of the buds of an early (cv. Maximus) and a late (cv. Philemon) cultivar of Brussels sprout (Brassica oleracea var. gemmifera). The efficiency of nitrogen application, with the aim of increasing the nitrogen concentration in the outer leaflets of the buds, was higher when nitrogen dissolved in water was directly sprayed over the crop as compared with the conventional broadcast granular fertilizer application. However, there appeared to be no relation between the nitrogen concentration of the outer leaflets of the buds and the time after harvest to reach 25% yellow buds. For both cultivars the rate of postharvest yellowing increased with a delay in harvest and was positively related to the size of the buds. When all data were pooled, it appeared that for the early cv. Maximus the time after harvest to reach 25% yellow buds was negatively correlated with the age of the crop at the time of harvesting. Such a relation was not found for the late cv. Philemon. The age of the buds, and not nitrogen concentration, is likely to be the dominant factor determining postharvest yellowing.