Cg. Downs et al., CYTOKININ TREATMENT DELAYS SENESCENCE BUT NOT SUCROSE LOSS IN HARVESTED BROCCOLI, Postharvest biology and technology, 11(2), 1997, pp. 93-100
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 tr
eatment did not prevent the rapid loss of sucrose that occurs in flore
ts after harvest. During the first 6 h after harvest, sucrose concentr
ation declined by approximately 50% in both controls and treated tissu
es. However, after cytokinin treatment the large increases in asparagi
ne and glutamine concentration were delayed by more than 48 h. Cytokin
in treatment also altered the physiological changes which usually acco
mpany the yellowing of broccoli florets. The decline in amino acids an
d soluble proteins, and the late increase in ammonia concentration wer
e all delayed after cytokinin treatment. We discuss these results in r
elation to the effects of cytokinin treatment on the possible mechanis
ms regulating postharvest senescence. (C) 1997 Elsevier Science B.V.