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

A study was made of the effect of nitrogen application shortly before harve st on postharvest yellowing of the buds of an early (cv. Maximus) and a lat e (cv. Philemon) cultivar of Brussels sprout (Brassica oleracea var. gemmif era). The efficiency of nitrogen application, with the aim of increasing th e 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 b uds. 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 a ll data were pooled, it appeared that for the early cv. Maximus the time af ter 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 t he late cv. Philemon. The age of the buds, and not nitrogen concentration, is likely to be the dominant factor determining postharvest yellowing.