The Influence of Temperature on the Respiration Rate and Browning of Protea Nerriifolia R Br Inflorescences

Ferreira, D. I.

doi:10.17660/actahortic.1986.185.12

Cited by 11 publications

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“…Also, it has been reported that degradation and leakage of membranes in 'Mercedes' rose petals was slowed when stems were treated with 2% sugar solution (Goszcynska et al, 1990). Ferreira (1986) reported that the P. neriifolia inflorescence follows a climacteric pattern of respiration, which precedes the final stages of senescence (Halevy and Mayak, 1979). Our data suggest that inflorescences in the light experiment without exogenous sugar reached a respiratory peak near day 7 and subsequently senesced.…”

Section: Figsupporting

confidence: 57%

“…Leaves of susceptible species begin to turn black within 3 to 7 days after harvest, severely reducing the market value of a flower stem that otherwise has a potential vase life of 3 to 4 weeks. Leaf blackening appears to be caused by oxidation of the polyphenols and leuco-anthocyanins (Whitehead and de Swardt, 1982) that leak into the cyfosol from the vacuole after rupture of intracellular membranes (Brink and de Swardt, 1986;Ferreira, 1986;Newman et al, 1989). The physiological mechanisms or stresses that initiate rupture of the intracellular membrane and subsequent leaf blackening have not been clearly established.…”

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confidence: 99%

“…However, leaf blackening is known to decrease significantly when the influence of the inflorescence sink is eliminated by girdling the stem immediately below the inflorescence or by removing it (Newman et al, 1989;Paull et al, 1980). Blackening is also reduced by lighted postharvest conditions (Newman et al, 1989) and the addition of external sugar to the vase solution at concentrations ranging from 0.5% to 1.0% (Brink and de Swardt, 1986;Ferreira, 1986;Newman et al, 1989). These observations suggest that depletion of carbohydrates from leaves, caused by translocation to the strong inflorescence sink, may play a role in initiating the cascade of events that leads to leaf blackening.…”

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confidence: 99%

“…To maximize inflorescence vase life, the Protea inflorescence is generally harvested when the involucral bracts are beginning to unfold. At this stage, many of the flowers inside the bracts are immature and have a high respiratory requirement to complete development (Ferreira, 1986) and produce nectar. Thus, the developing in florescence is probably a very strong sink that cannot be supported adequately by carbohydrate pools in source leaves and stems of cut flowers under dark postharvest conditions.…”

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Carbohydrate Depletion and Leaf Blackening in Protea neriljiolia

McConchie¹,

Lang²,

Gross³

1991

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Leaf blackening on cut flower Protea nerii[olia R. Br. stems was dramatically reduced under a 12-hour photosynthetic light period (120 μmol·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 maybe 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.

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Carbohydrate Depletion and Leaf Blackening in Protea neriljiolia

McConchie¹,

Lang²,

Gross³

1991

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“…The immature Protea inflorescence represents a substantial sink that can deplete the majority of leaf starch reserves within 24 h of harvest (Table 1) (McConchie and Lang, 1993b;McConchie et al, 1991). Although it has been hypothesized that decreased leaf carbohydrate status can result in hydrolysis of membrane-bound macromolecules (Ferreira, 1986), there is no evidence of membrane disruption before the onset of leaf blackening (McConchie and Lang, 1993b). Alternatively, considering that starch has minimal osmotic activity (Setter, 1990), the rapid rate of starch hydrolysis in response to sink demand may impose osmotic stress on leaf cells.…”

Section: Discussionmentioning

confidence: 99%

Reexamining Polyphenol Oxidase, Peroxidase, and Leaf-blackening Activity in Protea

McConchie¹,

Lang²,

Lax³

et al. 1994

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Premature leaf blackening in Protea severely reduces vase life and market value. The current hypothesis suggests that leaf blackening is induced by a sequence of events related to metabolic reactions associated with senescence, beginning with total depletion of leaf carbohydrates. It is thought that this carbohydrate depletion may induce hydrolysis of intercellular membranes to supply respiratory substrate, and subsequently allow vacuole-sequestered phenols to be oxidized by polyphenol oxidase (PPO) and peroxidase (POD) (Whitehead and de Swardt, 1982). To more thoroughly examine this hypothesis, leaf carbohydrate depletion and the activities of PPO and POD in cut flower Protea susannae × P. compacta stems held under light and dark conditions were examined in relationship to postharvest leaf blackening. Leaf blackening proceeded rapidly on dark-held stems, approaching 100% by day 8, and was temporally coincident with a rapid decline in starch concentration. Blackening of leaves on light-held stems did not occur until after day 7, and a higher concentration of starch was maintained earlier in the postharvest period for stems held in light than those held in dark. A large concentration of the sugar alcohol, polygalatol, was maintained in dark- and light-held stems over the postharvest period, suggesting that it is not involved in growth or maintenance metabolism. Polyphenol oxidase activity in light- and dark-held stems was not related to appearance of blackening symptoms. Activity of PPO at pH 7.2 in light-held stems resulted in a 10-fold increase over the 8-day period. Activity in dark-held stems increased initially, but declined at the onset of leaf blackening. There was no significant difference in POD activity for dark- or light-held stems during the postharvest period. Total chlorophyll and protein concentrations did not decline over the 8-day period or differ between light- and dark-held stems. Total phenolics in the dark-held stems increased to concentrations ≈30% higher than light-held stems. Consequently, the lack of association between membrane collapse, leaf senescence, or activities of oxidative enzymes (PPO or POD) with leaf blackening does not support the hypothesis currently accepted by many Protea researchers. An alternative scenario may be that the rapid rate of leaf starch hydrolysis imposes an osmotic stress resulting in cleavage of glycosylated phenolic compounds to release glucose for carbohydrate metabolism and coincidentally increase the pool of free phenolics available for nonenzymatic oxidation. The physiology of such a carbohydrate-related cellular stress and its manifestation in cellular blackening remains to be elucidated.

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Banksia:New Proteaceous Cut Flower Crop

Sedgley¹

1998

Horticultural Reviews

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More than 1400 species have been recognized in the ancient Proteaceae family (Rebelo 1995). Their occurrence is mostly distributed between Australia with about 800 species and Africa with about 400 species with the remainder found in South America, the islands east of New Guinea, and a few species in southeast Asia, New Zealand, and Madagascar. They are broadly referred to as proteas, although we identify specific genera by their Latin names. The subfamily Proteoideae, largely found in Africa, has contributed the genera Protea, Leucadendron, and Leucospermum to floricultural trade, while the Australian Grevilleoideae has contributed Banksia and Grevillea that have found similar use in floriculture and landscaping. Other genera are still emerging in importance (Criley, 2001

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The Influence of Temperature on the Respiration Rate and Browning of Protea Nerriifolia R Br Inflorescences

Cited by 11 publications

References 0 publications

Carbohydrate Depletion and Leaf Blackening in Protea neriljiolia

Carbohydrate Depletion and Leaf Blackening in Protea neriljiolia

Reexamining Polyphenol Oxidase, Peroxidase, and Leaf-blackening Activity in Protea

Banksia:New Proteaceous Cut Flower Crop

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