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  • Author or Editor: John N. Sacalis x
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It has previously been demonstrated that exceedingly high concentrations of 2,4-D, when taken up by cut carnations, inhibit petal senescence, while application of low concentrations of this synthetic auxin promote petal senescence. The mode of action of such high concentrations of 2,4-D has not been elucidated.

In previous work, it was observed that significant amounts of volatiles always emanated from those flowers treated with high 2,4-D, and which displayed inhibition of ethylene synthesis as well as petal senescence. In the present work, the headspace of treated flowers was therefore tested by gas chromatography after enclosure for a short period of time. Two of the major constituents of the volatiles produced by the treated flowers were found to be ethanol and acetaldehyde.

Since ethanol has formerly been shown to delay senescence in carnation flowers, and since 2,4-D has been shown to induce alcohol dehydrogenase, it is suggested that the mode of action of 2,4-D in this case is by means of the ethanol produced as a result of the 2,4-D treatment.

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Abstract

Treatement of cut roses with sugers such as surcose appreciably extends their postharvest life. Sucrose serves as a metabolic energy source, but it is probable that sucrose may play additional roles in restricing the loss of water from floral tissue.

Open Access

Abstract

Cut roses (Rosa hybrida L. cv. White Butterfly) pulsed with 14C-sucrose were analyzed for changes in total and labeled sucrose, glucose, fructose and starch after chases of various periods in either water or sucrose solution. Changes of 14C in an ethanol-insoluble fraction defined as the “cell wall fraction” were also studied. Changes in total amounts of each sugar did not correspond to changes in their respective labeled sugars, and these dissimilariteis in pattern indicated rapid turnover of each sugar in stems, and moderate turnover in leaves, with a general movement of 14C out of both leaves and stems. In flower heads, there was an initially short, overall incorporation of labeled sugars, followed by a gradual increase of 14C-glucose and 14C-fructose, but not 14C-sucrose. Starch turnover was appreciable in flower heads and in leaves, but not in stems. The leaves of roses held in the water chase showed the greatest turnover of starch. Incorporation of 14C into that portion of the ethanol-insoluble fraction designated “cell wall fraction” was greater in flower heads of roses chased in sucrose than those chased in water, but the type of chase solution used had little effect on incorporation of 14C into the “cell wall fraction” of leaf and stem tissue.

Open Access

Abstract

14C-sucrose, when taken up into the xylem, moved rapidly into leaves and flower heads of cut roses (Rosa hybrida L.) Outward lateral movement of 14C occurred rapidly along the entire length of stem at a uniform rate, regardless of l4C-sucrose concentration within the xylem and associated tissues. The quantity of 14C inverted sugars found in xylem tissue after uptake of 14C sucrose, and the rapid hydrolysis of sucrose passing through xylem of isolated stem segments suggests the involvement of invertase located in the xylem.

Open Access

Abstract

Labeling patterns of absorbed 14C sugars in petal discs of ‘Forever Yours’ rose (Rosa hybrida L.) revealed that most of the sucrose was absorbed undegraded indicating that inversion was not a prerequisite for absorption of sucrose by petal tissue.

Open Access

Abstract

In the paper by John N. Sacalis and Dominic Durkin, J. Amer. Soc. Hort. Sci. 97(4):481-484, 1972, an erroneous list of numbers was given in Table 3 (on page 484) to represent radioactivity in c.p.m. The corrected Table appears below, and can be clipped and pasted over Table 3 in Vol. 97(4):484.

Open Access

Abstract

Movement of 14C was studied in cut roses and carnations using a pulse of 14C-sucrose and a distilled water chase. The label moved selectively to leaves and stems, but not to flower heads during the pulse. During the chase, however, 14C moved from leaves and stems into the flower heads. Age had no effect on this movement into rose flower heads, but movement of 14C into carnation flower heads diminished as cut carnations aged.

It was established by girdling cut rose stems that assimilates are translocated from leaves and stems to flower heads via the phloem.

Open Access

Abstract

Cut carnation (Dianthus caryophyllus L.) flowers held in sucrose have a substantially longer vase life than flowers held in water. Excision of the gynoecium does not affect the longevity of flowers in water; however, gynoecia excision did reduce flower longevity when stems were supplied sucrose. Maintenance of cut flower life by the gynoecium was apparently due to the presence of the ovary and not the styles. Excision of gynoecia from buds of intact carnation flowers left to age on the plant also reduced longevity. Gynoecium removal did not result in a significant reduction of total sucrose or glucose in petal content of flowers held in a sucrose solution for 5 days, but absence of the gynoecium did result in a slightly but significantly lower fructose content in petals. It is suggested that the reduction in longevity resulting from gynoecium excision is not due to the failure of petals to take up sugars.

Open Access

Abstract

Leaf abscission was promoted in Ficus benjamina L. (weeping fig) by withholding water from plants growing in sand and by the addition of polyethylene glycol 6000 to hydroponically-grown plants. Leaf shedding occurred when plant water potential decreased below about −6 bar in sand and below −3.5 bar in water culture. Shoot and root environmental conditions modified the water status of plants. Leaf shedding can be dramatically reduced by manipulating environmental conditions to maximize water absorption and minimize transpiration.

Open Access

Abstract

Relationships were examined among water deficits, ABA content of leaf tissue, and leaf abscission in intact Ficus benjamina L. (weeping fig). Water deficits were imposed by withholding water from plants growing in sand and by raising the osmotic potential of water culture solutions through the addition of PEG 6000. Unconjugated ABA was quantitatively analyzed using gas chromatography. A strong inverse linear correlation existed between ABA content of leaves and plant water potential. No relationships between ABA content and leaf abscission were observed. ABA content in leaves collected from plants growing in a greenhouse, having a plant water potential of −0.5 bar, was about 75 fold greater than the ABA content of leaves collected from plants maintained in a controlled environment room, having plant water potentials of −8.0 bar. Results indicate that ABA does not independently regulate leaf abscission in Ficus benjamina.

Open Access