+ Translate

Carbohydrate depletion and leaf blackening in Protea neriifolia

, : Carbohydrate depletion and leaf blackening in Protea neriifolia. Journal of the American Society for Horticultural Science 116(6): 1019-1024

Leaf blackening on cut flower Protea neriifolia R. Br. stems was dramatically reduced under a 12-hour photosynthetic light period (120 micromole.m-2.s-1) at 25C for 15 days compared with stems kept in the dark. In the light, addition of 0.5% exogenous sugar to the vase solution resulted in a maximum of 2.5% leaf blackening, while stems with no exogenous sugar had a maximum of 16.5%. Continuous darkness resulted in 94% leaf blackening by day 7, irrespective of sugar treatment. Starch and sucrose concentrations were markedly lower in leaves on dark-held stems than in leaves on stems held in the light; thus, carbohydrate depletion could be the primary stress that initiates leaf blackening. In the light, rates of carbon exchange and assimilate export were similar, indicating that the amount of carbon fixed may be regulated by sink demand. The pattern of carbon partitioning changed in light-held leaves of the 0% sugar treatment during rapid floral expansion and senescence. Inflorescence expansion appears to influence partitioning of photoassimilates and storage reserves into transport carbohydrates; under decreased sink demand, the assimilate export rate decreases and photoassimilates are partitioned into starch. The data suggest that sink strength of inflorescences held in darkness may be responsible for the depletion of leaf carbohydrates and, consequently, blackening.

(PDF 0-2 workdays service)

Accession: 002042895

Submit PDF Full Text: Here

Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:

Related references

Mcconchie, R.; Lang, N.S.zanne, 1993: Carbohydrate metabolism and possible mechanisms of leaf blackening in Protea neriifolia under dark postharvest conditions. During a 7-day dark postharvest period, Protea neriifolia R. Br. leaf blackening was significantly reduced on floral stems treated with a 24-h 20% sucrose pulse compared with continuous holding in a 0.5% sucrose vase solution or removal of the flo...

Mcconchie R.; Robbins N.S., 1990: Leaf blackening in protea neriifolia r br. Hortscience 25(9): 1087

Mcconchie R.; Lang N.S., 1992: Inflorescence sink demand and leaf blackening in protea neriifolia. Hortscience 27(6): 617

Jones, R.B.; Clayton-Greene, K.A., 1992: The role of photosynthesis and oxidative reactions in leaf blackening of protea neriifolia r. br. leaves. A series of experiments with Protea neriifolia R. Br. found evidence that leaf blackening is associated with the inhibition of photosynthesis and its resultant effect on oxidative metabolism. Leaf blackening was significantly reduced by constant i...

Dai JingWei; Paull, R.E., 1997: Comparison of leaf susceptibility to enzymatic blackening in Protea neriifolia R. Br. and Leucospermum 'Rachel'. Leaf susceptibility to blackening differs between cut flowers of Protea neriifolia and Leucospermum cv. Rachel ((L. lineare x L. vestitum) x L. glabrum); members from different genera of the family Proteaceae. Leaf discs from mature green leaves o...

Bieleski, R.; Ripperda, J.N.wman, J.; Reid, M., 1992: Carbohydrate changes and leaf blackening in cut flower stems of Protea eximia. We tested the hypothesis that premature leaf blackening in cut flower stems of Protea eximia (Salisb. ex Knight) Fourcade may be brought about by a low leaf carbohydrate status. Leaves on cut flower stems held in darkness blackened within 4 days,...

Mcconchie, R.; Lang, N.S.zanne, 1993: Postharvest leaf blackening and preharvest carbohydrate status in three Protea species. Protea neriifolia R. Br., P. susannae E.P. Phillips x compacta R.Br., and P. eximia (Salis. ex Knight) Fourcade cut flower stems were examined to determine the relationship between postharvest leaf blackening rate and preharvest carbohydrate statu...

Reid M.S.; Van Doorn W.; Newman J.P., 1989: Leaf blackening in protea. Acta Horticulturae (Wageningen) (261): 81-84

Dai J.; Paull R.E., 1992: Protea leaf blackening. Hortscience 27(6): 616

Jones, R.B.; Mcconchie, R.; Van Doorn, W.G.; Reid, M.S., 1995: Leaf blackening in cut Protea flowers. Janick, J [Editor] Horticultural Reviews 173-201