Cytokinin treatment delays senescence but not sucrose loss in harvested broccoli

Abstract

Abstract We describe details of the physiological changes that both precede and accompany visual deterioration in harvested broccoli floral tissues ( Brassica oleracea L.), and show that some of these changes are altered after treatment with the cytokinin, 6-benzylaminopurine. Cytokinin treatment did not prevent the rapid loss of sucrose that occurs in florets after harvest. During the first 6 h after harvest, sucrose concentration declined by approximately 50% in both controls and treated tissues. However, after cytokinin treatment the large increases in asparagine and glutamine concentration were delayed by more than 48 h. Cytokinin treatment also altered the physiological changes which usually accompany the yellowing of broccoli florets. The decline in amino acids and soluble proteins, and the late increase in ammonia concentration were all delayed after cytokinin treatment. We discuss these results in relation to the effects of cytokinin treatment on the possible mechanisms regulating postharvest senescence.