Ethephon-Induced Gummosis in Sour Cherry (Prunus cerasus L.)

Abstract

Ethephon, (2-chloroethyl)phosphonic acid, was sprayed at concentrations up to 69.2 millimolar to enhance gum formation in 1-year-old shoots of mature Pruns cerasus L. cv Montmorency trees. Gum accumulation caused rupturing of the shoot periderm, followed by gum extrusion. Lower ethephon concentrations were required to induce gum formation in spring and early summer (1.7-3.5 millimolar) then in late summer and fall (13.8-69.2 millimolar). The number of functional vessels, shoot hydraulic conductance, and water potential of both leaf and internode tissue decreased as gum content of shoots increased. Nontreated control shoots also contained small quantities of gum. There was no difference in neutral sugar composition of gum exuded by the tree, obtained from aqueous shoot extracts, or flushed from the vessels of shoots, whether induced by ethephon or not. Severe decrease in shoot and leaf water potential was associated with shoot die-back. Recovery of xylem function may occur where gummosis is less severe. Discrepancy between measured and predicted hydraulic conductance increased as shoot gum content increased, suggesting that decrease in number of functional vessels alone was not sufficient to explain the effects of gum on loss of shoot hydraulic conductance. Increased gum content in those vessels remaining functional would increase vessel sap viscosity and further reduce hydraulic conductance. The viscosities necessary to account for discrepancy between measured and predicted hydraulic conductance were calculated. Gum concentration less than 1.0%

Ethephon-Induced Abscission of “Redhaven” Peach

“…One of the primary concerns is ethephon's inconsistency when used as a thinning agent [2,3]. Ethephon degradation and subsequent release of ethylene gas is highly temperature dependent [35,36], at least outside the window of 21˚C -32˚C [37]. Another concern, a direct consequence of thinning either by hand or with ethephon, is the decrease in total yield per tree.…”

Gum Accumulation of Japanese Apricot Fruit (Prunus mume Sieb. et Zucc.) was Expedited by Jasmonate

“…Gum accumulation is known to be induced by ethylene evolution in many plant species (Bukovac, 1979;Martin and Nelson, 1969;Morrison et al, 1987;Olien and Bukovac, 1982). In our experiment, gum accumulation induced by artificial wounding on 3 June appears to have occurred on account of ethylene evolution (Table 1 and Fig.…”

“…A previous report (Matsumoto et al, 2008) indicated that, in mid-May, gum duct initiation and plant gum accumulation could be observed in vascular bundles in the mesocarp tissue of both 'Benisashi' and 'Nanko' Japanese apricot fruit; however, although 'Nanko' fruit does not develop a gum lump that is visible to the naked eye until the mature stage, 'Benisashi' fruit develops clearly visible gum lumps. Morrison and Polito (1985) reported that a gum duct forms naturally in many kinds of cultivated Prunus species; however, gum production is intensified after mechanical or insect damage, pathogenic infection, or 274 exposure to ethylene-producing chemicals (Bukovac, 1979;Martin and Nelson, 1969;Morrison et al, 1987;Olien and Bukovac, 1982;Saniewski et al, 2006). All of these factors that stimulate gum exudation have been shown to promote ethylene production in plant tissue (Boothby, 1983).…”

Ethephon-Induced Gummosis in Sour Cherry (Prunus cerasus L.)

“…Gum synthesis and accumulation in Prunus is promoted by stress and wounding (2, 3, 6, 7) or more directly by ethylene (1, 10). The gum formed can enter the xylem vessels and interfere with flow through the vessels both by increasing vessel sap viscosity and by occlusion of vessels (14).…”

“…Gum synthesis and accumulation in Prunus is promoted by stress and wounding (2, 3, 6, 7) or more directly by ethylene (1, 10). The gum formed can enter the xylem vessels and interfere with flow through the vessels both by increasing vessel sap viscosity and by occlusion of vessels (14).Laminar flow through capillaries is described by the Hagen- (5,8,11,16,17) and a summary is provided in Figure 1 The objective of this study was to establish the effect of gum concentration and applied pressure gradient on the flow characteristics of aqueous sour cherry gum solutions, and to relate these effects to conduction of sap through xylem vessels of sour cherry shoots.MATERIALS AND METHODS Test Solutions. Clear, nonpigmented gum exudates were collected from branches of mature sour cherry Prunus cerasus L. cv.…”