scholarly journals Studies on Water Transport through the Sweet Cherry Fruit Surface: XII. Variation in Cuticle Properties among Cultivars

2012 ◽  
Vol 137 (6) ◽  
pp. 367-375 ◽  
Author(s):  
Stefanie Peschel ◽  
Moritz Knoche
Keyword(s):  
Water Uptake ◽  
Variance Components ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Stomatal Density ◽  
Error Variance ◽  
Cuticular Membrane ◽  
Lower Permeability ◽  
Estimate Variance ◽  
Fruit Mass

The cuticular membrane (CM) represents the primary barrier to water uptake into sweet cherry (Prunus avium L.) fruit and thus has a central role in rain-induced cracking. The objective was to quantify CM properties potentially relevant to cracking and to estimate variance components and broad-sense heritabilities for these traits in selected sweet cherry cultivars. Within the scion cultivars, CM mass per area ranged from 0.85 g·m−2 in ‘Rainier’ to 1.61 g·m−2 in ‘Kordia’. Wax mass accounted for one-fourth of CM mass and ranged from 0.21 g·m−2 in ‘Burlat’ to 0.42 g·m−2 in ‘Zeppelin’. Biaxial elastic strain of the CM averaged 76.7% across cultivars and ranged from 56.6% in ‘Namosa’ to 97.0% in ‘Oktavia’. Strain was a linear function of fruit mass (r2 = 0.33, P < 0.0001). Partitioning total variance into variance components revealed that fruit mass, CM, and wax mass and strain of the CM had a high genotypic variance and a low residual error variance. Stomatal density ranged from 0.12 stomata/mm2 in ‘Adriana’ to 2.13 stomata/mm2 in ‘Namosa’. The heritability of stomatal density was 67.5%. Across cultivars and years, mean densities of microcracks were of similar orders of magnitude as those of stomata, but ranges were larger and the heritabilities of microcrack density lower. Permeability for transpiration was lowest in ‘Flamingo Srim’ and highest in ‘Nadino’; that for osmotic water uptake was lowest in ‘Adriana’ and highest in ‘Hedelfinger’. Heritability estimates for permeabilities were low. Based on these data, breeding strategies for less cracking susceptible fruit should focus on genotypes that maintain an intact CM throughout development. This may be achieved by selecting for low CM strain and high CM thickness because thicker CM have more “reserve” for thinning. Finally, genotypes that deposit cutin and wax also during Stage III would be most interesting but were not found among the cultivars investigated.

scholarly journals Effect of Receiver pH on Infinite Dose Diffusion of 55FeCl3 across the Sweet Cherry Fruit Exocarp

2010 ◽  
Vol 135 (2) ◽  
pp. 95-101
Author(s):  
Holger Weichert ◽  
Stefanie Peschel ◽  
Moritz Knoche ◽  
Dieter Neumann
Keyword(s):  
Water Uptake ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Stomatal Density ◽  
Analytical Electron Microscopy ◽  
Precipitation Reaction ◽  
Ph Values ◽  
Fruit Cracking ◽  
Analytical Electron ◽  
Electron Energy Loss

Recent studies established that some ferric salts, including FeCl3, decrease water permeability of the sweet cherry (Prunus avium L.) fruit exocarp and fruit cracking, presumably by a pH-dependent precipitation reaction that blocks high-flux pathways across the fruit surface. The objectives of our study were the following: to establish the effect of receiver pH on penetration of 55FeCl3 through excised exocarp segments (ES) and isolated cuticular membranes (CM) and to localize any Fe precipitates in the epidermal system of mature sweet cherry fruit. Penetration was studied using an infinite dose diffusion system where 55Fe penetrated from donor solutions of ferric salts (10 mm, pH 2.2–2.6) or EDTA-Na-Fe(III) (10 mm, pH 5.0) across an interfacing ES or CM into aqueous receiver solutions of pH values ranging from 2.0 to 6.0. For receiver pH 2.0, 55Fe penetration of the ES from a 10 mm FeCl3 donor (pH 2.6) was linear with time, but for receiver pH ≥ 3.0, penetration was low and insignificant. Increasing the pH of the water receiver from 2.0 to 6.0 in the course of an experiment resulted in an immediate halt of penetration regardless of whether 55Fe penetration occurred from FeCl3 (pH 2.6), Fe(NO3)3 (pH 2.6), or Fe2(SO4)3 (pH 2.4) as donor solutions (all at 10 mm). Only from EDTA-Na-Fe(III) (pH 5.0) 55Fe penetration continued to occur albeit at a decreased rate (−30%). At receiver pH 2.0, the 55FeCl3 flux through stomatous ‘Sam’ ES averaged 10.4 ± 2.3 pmol·m−2·s−1 and was positively correlated to stomatal density. Conventional and analytical electron microscopy (energy dispersive X-ray analysis, electron spectroscopic imaging, and electron energy loss spectroscopy) identified ferric precipitates in periclinal and anticlinal cell walls of epidermal cells underlying the cuticle, but not within the cuticle. These data indicate that the lack of 55Fe penetration from donor solutions of ferric salts through the ES into a receiver solution at pH ≥ 3 and the previously reported decrease in water uptake and cracking as a response to immersing fruit in solutions of ferric salts are the result of a precipitation reaction at the cuticle/cell wall interface in the sweet cherry exocarp. Although spray application of ferric salts is prohibitive for ecotoxicological reasons, understanding their mechanism in decreasing water uptake and fruit cracking may be helpful in the search for alternate compounds that are effective and ecotoxicologically acceptable.

scholarly journals 595 The Cuticular Membrane: A Critical Factor in Rain-induced Cracking of Sweet Cherry Fruit

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 549D-549 ◽  
Author(s):  
Martin J. Bukovac ◽  
Alicia Pastor ◽  
Royal G. Fader ◽  
Moritz Knoche
Keyword(s):  
Water Uptake ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Contact Angles ◽  
Critical Surface ◽  
Reduced Pressure ◽  
Cuticular Membrane ◽  
Fruit Cracking ◽  
Chloroform Methanol ◽  
Fruit Surface

Morphological and physical characteristics of the cuticular membrane (CM) of selected cultivars of sweet cherry (Prunus avium L.) fruit were studied relative to rain-induced cracking. Two characteristics of the CM may be determinants in rain-induced fruit cracking. The surface morphology and chemistry determine surface wettability and water retention, and the morphology and physicochemical characteristics its water permeability. The fruit epidermis as well as the guard cell walls adjacent to the outer vestibule and stomatal pore are covered by a thin lipoidal CM. Stomata were present at a frequency of 0.1 to 2 per mm2 depending on cultivar and fruit surface position. However, most appeared nonfunctional with many pores partially or completely occluded with wax-like material. There was no evidence of water (containing fluorescein or AgNO3) penetration into stomatal pores following surface application or submerging fruit for short periods. There was stomatal pore penetration when submerged fruit were infiltrated by reduced pressure in the presence of 0.1% L-77. Preferential sorption of AgNO3 and fluorescein by cuticular ledges and guard cells was noted. The epicuticular wax (ECW) had no significant fine-structure. The CM was isolated enzymatically (cellulase/pectinase) and found to be 1 to 2 μm thick with an area weight of 1.2 to 2.3 g·m–2, of which 25% to 40% was chloroform/methanol (1: 1by vol.) soluble. Fractionation of the chloroform/methanol fraction indicated the presence of four groups of nonpolar constituents. The fruit surface was moderately difficult to wet, forming contact angles of 85% to 105%, and with an estimated critical surface tension in the range of 16-24 mN·m–1. Fruit water loss (transpiration) and uptake on submersion was followed and found to be complex. Transpiration increased with an increase in temperature, and both rate of transpiration and water uptake increased after removal of the epicuticular and cuticular waxes. Pathways of water uptake and the significance of our findings to rain-induced fruit cracking will be discussed.

scholarly journals Characterization of Microcracks in the Cuticle of Developing Sweet Cherry Fruit

2005 ◽  
Vol 130 (4) ◽  
pp. 487-495 ◽  
Author(s):  
Stefanie Peschel ◽  
Moritz Knoche
Keyword(s):  
Surface Area ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Epidermal Cells ◽  
Width Ratio ◽  
Similar Data ◽  
Cuticular Membrane ◽  
Osmotic Water ◽  
Periclinal Walls ◽  
Fruit Mass

Frequency and distribution of microcracks in the cuticular membrane (CM) were monitored in cheek, suture, pedicel cavity and stylar regions of developing sweet cherry (Prunus avium L.) fruit using fluorescence microscopy following infiltration with a fluorescence tracer (1 to 2 min in 0.1% w/v acridine orange containing 50 mm citric acid and 0.1% Silwet L-77, pH 6.5). These microcracks were limited to the cuticle, did not extend into the pericarp and were only detected by microscopy. Fruit mass and surface area increased in a sigmoidal pattern with time between 16 days after full bloom (DAFB) and maturity. The increase in frequency of fruit with microcracks paralleled the increase in fruit mass. During early development (up to 43 DAFB) the CM of `Sam' fruit remained intact. However, by 57 DAFB essentially all `Sam' fruit had microcracks in the pedicel cavity and ≈25% in the suture region with little change thereafter. At maturity percentage of `Sam' fruit with microcracks in cheek, suture, pedicel cavity and stylar end region averaged 23%, 25%, 100%, and 63%, respectively. Similar data were obtained for `Hedelfinger' (70% and 100% for cheek and pedicel cavity, respectively), `Kordia' (80% and 100%) and `Van' (100% and 100%). Generally, microcracks were most severe in pedicel cavity and stylar end region. Most of the first detectable microcracks formed above periclinal walls of epidermal cells perpendicular to their longest axis (72% and 92% in cheek and stylar regions, respectively). The other microcracks formed above the anticlinal walls were mostly oriented in the direction of the underlying cell wall. There was no difference in projected surface area, length/width ratio or orientation among epidermal cells below, adjacent to or distant from the first detectable microcracks in the CM. However, as length of microcracks increased the projected surface area of cells underlying cracks increased suggesting strain induced upon cracking of the CM. Permeability of excised exocarp segments in osmotic water uptake was positively correlated with number of stomata and number of microcracks in the CM. From our results we suggest that strain of the epidermal system during stage III of fruit growth is a factor in “microcracking” of the CM that may predispose fruit to subsequent rain-induced cracking.

scholarly journals Studies on Water Transport through the Sweet Cherry Fruit Surface: V. Conductance for Water Uptake

2002 ◽  
Vol 127 (3) ◽  
pp. 325-332 ◽  
Author(s):  
Marco Beyer ◽  
Moritz Knoche
Keyword(s):  
Water Uptake ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Stomatal Density ◽  
Surface Conductance ◽  
Diffusion Cell ◽  
Storage Duration ◽  
Flow Rates ◽  
Fruit Cracking ◽  
Fruit Surface

Rain-induced cracking of sweet cherry (Prunus avium L.) fruit is thought to be related to water absorption through the fruit surface. Conductance for water uptake (gtot. uptake) through the fruit surface of `Sam' sweet cherry was studied gravimetrically by monitoring water penetration from a donor solution of deionized water through segments of the outer pericarp into a polyethyleneglycol (PEG) containing receiver solution. Segments consisting of cuticle plus five to eight cell layers of epidermal and hypodermal tissue were mounted in stainless steel diffusion cells. Conductance was calculated from flow rates of water across the segment and the difference in osmotic potential between donor and receiver solution. Flow rates were constant up to 12 hours and decreased thereafter. A log normal distribution of gtot. uptake was observed with a median of 0.97 × 10-7 m·s-1. Further, gtot. uptake was not affected by storage duration (up to 71 days) of fruit used as a source of segments, thickness of segments (range 0.1 to 4.8 mm), or segment area exposed in the diffusion cell. Osmolality of the receiver solution in the range from 1140 to 3400 mmol·kg-1 had no effect on gtot. uptake (1.45 ± 0.42 × 10-7 m·s-1), but gtot. uptake increased by 301% (4.37 ± 0.46 × 10-7 m·s-1) at 300 mmol·kg-1. gtot. uptake was highest in the stylar scar region of the fruit (1.44 ± 0.16 × 10-7 m·s-1) followed by cheek (1.02 ±0.21 × 10-7 m·s-1), suture (0.57 ±0.17 × 10-7 m·s-1) and pedicel cavity regions (0.22 ±0.09 × 10-7 m·s-1). Across regions, gtot. uptake was related positively to stomatal density. Extracting total cuticular wax by dipping fruit in chloroform/methanol increased gtot. uptake from 1.18 ± 0.23 × 10-7 m·s-1 to 2.58 ± 0.41 × 10-7 m·s-1, but removing epicuticular wax by cellulose acetate stripping had no effect (1.59 ± 0.28 × 10-7 m·s-1). Water flux increased with increasing temperature (range 20 to 45 °C). Conductance differed between cultivars with `Hedelfinger' sweet cherry having the highest gtot. uptake (2.81 ± 0.26 × 10-7 m·s-1), followed by `Namare' (2.68 ± 0.26 × 10-7 m·s-1), `Kordia' (0.96 ± 0.14 × 10-7 m·s-1), `Sam' (0.87 ± 0.15 × 10-7 m·s-1), and `Adriana' (0.33 ± 0.02 × 10-7 m·s-1). The diffusion cell system described herein may be useful in analyzing conductance in water uptake through the fruit surface of sweet cherry and its potential relevance for fruit cracking.

scholarly journals Water on the Surface Aggravates Microscopic Cracking of the Sweet Cherry Fruit Cuticle

2006 ◽  
Vol 131 (2) ◽  
pp. 192-200 ◽  
Author(s):  
Moritz Knoche ◽  
Stefanie Peschel
Keyword(s):  
Outer Surface ◽  
Liquid Water ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Developmental Stages ◽  
Tensile Tests ◽  
Deionized Water ◽  
Cuticular Membrane ◽  
High Concentrations ◽  
Fruit Surface

The effect of surface water on the frequency of microcracks in the cuticular membrane (CM) of exocarp segments (ES) of developing sweet cherry fruit (Prunus avium L.) was studied. Strain of CM and ES on the fruit surface was preserved by mounting a stainless steel washer on the fruit surface in the cheek region using an ethyl-cyanacrylate adhesive. ES were excised by tangentially cutting underneath the washer. Frequency of microcracks in the CM of ES was determined following infiltration for 10 minutes with a 0.1% acridine orange solution by fluorescence microscopy before and after exposure to deionized water (generally 48 hours). Exposing the surface of ES of mature `Burlat' sweet cherry fruit to water resulted in a rapid increase in microcracks in the CM that approached an asymptote at about 30 microcracks/cm2 within 24 hours. There was no change in microcracks in the CM when the surface of the ES remained dry. Incubating ES in polyethylene glycol solution that was isotonic to fruit juice extracted from the same batch of fruit resulted in a greater increase in frequency of microcracks as compared to incubation in deionized water. The water-induced increase in microcracks was closely related to strain of the CM across different developmental stages within a cultivar [between 45 and 94 days after full bloom (DAFB); r2 = 0.96, P ≤ 0.001, n = 9] or across different cultivars at maturity (r2 = 0.92, P ≤ 0.0022, n = 6). Incubating ES of developing fruit in enzyme solution containing pectinase and cellulase such that the outer surface remained dry resulted in complete rupture and failure of the ES. Time to rupture and percentage of ruptured ES were closely related to the strain of the CM (r2 = 0.92, P ≤ 0.001, n = 9 and r2 = 0.68, P ≤ 0.0063, n = 9, respectively). Removal of epicuticular wax had no effect on frequency of water-induced microcracks. Also, temperature had no effect on frequency of water-induced microcracks, but frequency of microcracks increased exponentially when exposing the outer surface of ES to relative humidities above 75%. At 100% humidity the increase in frequency of microcracks did not differ from that induced by liquid water. Local wetting the surface of intact fruit in the pedicel cavity or stylar end region resulted in formation of macroscopically visible cracks despite of a net water loss of fruit. Uniaxiale tensile tests using dry and fully hydrated CM strips isolated from mature `Sam' sweet cherry fruit established that hydration increased fracture strain, but decreased fracture stress and moduli of elasticity. Our data demonstrate that exposure of the fruit surface to liquid water or high concentrations of water vapor resulted in formation of microcracks in the CM.

scholarly journals Factors Affecting Mechanical Properties of the Skin of Sweet Cherry Fruit

2016 ◽  
Vol 141 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Martin Brüggenwirth ◽  
Moritz Knoche
Keyword(s):  
Mechanical Properties ◽  
Water Uptake ◽  
Cell Walls ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Biaxial Strain ◽  
Factors Affecting ◽  
Fruit Skin ◽  
Cell Turgor ◽  
Cell Layers

The skins of all fruit types are subject to sustained biaxial strain during the entire period of their growth. In sweet cherry (Prunus avium L.), failure of the skin greatly affects fruit quality. Mechanical properties were determined using a biaxial bulging test. The factors considered were the following: ripening, fruit water relations (including turgor, transpiration, and water uptake), and temperature. Excised discs of fruit skin were mounted in a custom elastometer and pressurized from their anatomically inner surfaces. This caused the skin disc to bulge outwards, stretching it biaxially, and increasing its surface area. Pressure (p) and biaxial strain (ε) due to bulging were quantified and the modulus of elasticity [E (synonyms elastic modulus, Young’s modulus)] was calculated. In a typical test, ε increased linearly with p until the skin fractured at pfracture and εfracture. Stiffness of the skin decreased in ripening late stage III fruit as indicated by a decrease in E. The value of pfracture also decreased, whereas that of εfracture remained about constant. Destroying cell turgor decreased E and pfracture relative to the turgescent control. The E value also decreased with increasing transpiration, while pfracture and (especially) εfracture increased. Water uptake had little effect on E, whereas εfracture and pfracture decreased slightly. Increasing temperature decreased E and pfracture, but had no effect on εfracture. Only the instantaneous elastic strain and the creep strain increased significantly at the highest temperatures. A decrease in E indicates decreasing skin stiffness that is probably the result of enzymatic softening of the cell walls of the skin in the ripening fruit, of relaxation of the cell walls on eliminating or decreasing turgor by transpiration and, possibly, of a decreasing viscosity of the pectin middle lamellae at higher temperatures. The effects are consistent with the conclusion that the epidermal and hypodermal cell layers represent the structural “backbone” of the sweet cherry fruit skin.

scholarly journals Pedicel Transpiration in Sweet Cherry Fruit: Mechanisms, Pathways, and Factors

2015 ◽  
Vol 140 (2) ◽  
pp. 136-143 ◽  
Author(s):  
Thomas O. Athoo ◽  
Andreas Winkler ◽  
Moritz Knoche
Keyword(s):  
Water Vapor ◽  
Prunus Avium ◽  
Stomatal Density ◽  
Vapor Concentration ◽  
Cuticular Membrane ◽  
Sweet Cherries ◽  
Postharvest Handling ◽  
And Storage ◽  
Rate Limiting

Pedicel appearance is a good indicator of freshness in sweet cherries (Prunus avium L.). Fruit with shriveled, discolored pedicels have reduced market value. Shriveled pedicels are thought to result from postharvest water loss due to transpiration. The objectives of our study were to 1) quantify the transpiration permeances of fruit and pedicel surfaces; 2) determine the role of the fruit in pedicel transpiration; and 3) identify the effects of selected factors on pedicel transpiration. Fruit with and without pedicels were incubated under controlled conditions [usually 22 °C, 75% relative humidity (RH)] and their mass losses determined gravimetrically. Pedicel transpiration was calculated by subtracting measured transpiration of fruit without pedicels from that of fruit with pedicels. Cumulative pedicel transpiration increased with time. Rates of pedicel transpiration were essentially constant over the first 0 to 1.5 hours but declined thereafter, approaching an asymptote over the subsequent period of 1.5 to 96 hours over which measurements were made. Cumulative pedicel transpiration exceeded the amount of water in the pedicel, indicating that at least some of the transpired water originated from the fruit. There was no significant effect of steam girdling on pedicel transpiration suggesting that water moved from the fruit to the pedicel through the xylem (steaming prevents phloem conduction). Abrading the cuticular membrane (CM) from a pedicel surface or extracting the cuticular wax by dipping pedicels once or five times in chloroform/methanol (1:1 v/v) increased rates of transpiration 12-, 3-, and 5-fold, respectively. The water vapor permeance of the pedicel surface determined under steady-state conditions (8.7 ± 0.4 × 10−4 m·s−1) exceeded that of the fruit (2.1 ± 0.1 × 10−4 m·s−1), possibly because of a more permeable CM and/or a higher stomatal density (38.5 ± 1.3 stomata/mm2 for pedicels vs. 1.1 ± 0.0 stomata/mm2 for fruit). Treatments known to affect stomatal opening (incubation in buffered abscisic acid at 0.1 mm or in CO2- or N2-atmospheres) had no effects on pedicel transpiration. Rates of transpiration were negatively correlated with RH but positively with temperature. There was no effect of RH and/or temperature on the permeances of pedicel or fruit surfaces. From our results it is inferred that 1) pedicel transpiration is a physical process governed by Fick’s law of diffusion, where cuticle and wax in particular represent the major rate-limiting barriers; 2) the permeances of pedicel surfaces exceed those of fruit surfaces; and 3) pedicel transpiration can be minimized by minimizing the driving force (difference in water vapor concentration) during postharvest handling and storage.

scholarly journals Studies on Water Transport Through the Sweet Cherry Fruit Surface: IV. Regions of Preferential Uptake

HortScience ◽  
2002 ◽  
Vol 37 (4) ◽  
pp. 637-641 ◽  
Author(s):  
Marco Beyer ◽  
Stefanie Peschel ◽  
Moritz Knoche ◽  
Manfred Knörgen
Keyword(s):  
Water Uptake ◽  
Time Course ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Deuterium Oxide ◽  
Full Bloom ◽  
Fruit Removal ◽  
Silicone Sealant ◽  
Preferential Uptake ◽  
Preferential Water

Water uptake in different regions of the sweet cherry fruit (Prunus avium L. cv. Sam) was investigated following selective application of silicone sealant to the pedicel end, pedicel cavity, pedicel/fruit juncture, or stylar scar of detached fruit. The time course of water uptake was monitored gravimetrically during a 3-hour incubation period in deionized water (20 °C). Sealing the pedicel end and/or pedicel/fruit juncture significantly reduced rates and total amount (3 hours) of water uptake, but sealing the stylar scar had no effect. The amount of water penetrating via the pedicel/fruit juncture increased between 50 and 85 days after full bloom. During the same period the maximum force required to detach pedicels from fruit (fruit removal force) fell from 5.2 ± 0.5 to 2.1 ± 0.2 N. The amount of water penetrating via the pedicel/fruit juncture and the fruit removal force were negatively related. Nuclear magnetic resonance (NMR) imaging of mature fruit incubated in D2O indicated that D2O accumulated in the pedicel cavity region and the pedicel. Our data suggest that the pedicel end and pedicel/fruit juncture, but not the stylar scar, are regions of preferential water uptake in detached fruit. Chemical name used: deuterium oxide (D2O).

scholarly journals Stress and Strain in the Sweet Cherry Skin

2012 ◽  
Vol 137 (6) ◽  
pp. 383-390 ◽  
Author(s):  
Eckhard Grimm ◽  
Stefanie Peschel ◽  
Tobias Becker ◽  
Moritz Knoche
Keyword(s):  
Elastic Strain ◽  
Time Course ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Silicone Oil ◽  
Stress And Strain ◽  
Biaxial Strain ◽  
Cuticular Membrane ◽  
Linear Elastic ◽  
Strain Release

Rain-cracking of sweet cherry (Prunus avium L.) fruit involves failure of the exocarp caused by excessive stress and strain. The objective of our study was to quantify exocarp strain in developing cherries. The release of linear elastic strain was followed in vivo using a gaping assay, whereas the release of biaxial elastic strain was followed in vitro after excision of small exocarp segments (ESs) that were submerged in silicone oil and strain release quantified by image analysis. When mature sweet cherry fruit were cut (by making two or more deep, longitudinal incisions parallel to the stylar/pedicel axis and on opposing sides of the fruit down to the pit), the incisions rapidly “gaped.” The gaping wounds continued to widen as they progressively released the linear elastic strain in the skin. By 24 hours the combined widths of two gapes represented 8.8% ± 0.1% of the fruit circumference. Increasing the number of cuts from two to 12 increased the cumulative gape widths to 14.9% ± 0.2%. In ES, monitoring the time course of relaxation after excision revealed a rapid release of biaxial strain, having a half-time of ≈2.7 minutes. Relaxation continued, but at a decreasing rate, for up to 48 hours. Across eight cherry cultivars, the biaxial strain in the exocarp at maturity ranged from 18.7% ± 1.9% in ‘Lapins’ to 36.0% ± 1.8% in ‘Katalin’. Elastic strain in the ES was always lower than that measured in an isolated cuticular membrane (CM). Increasing the temperature from 2 to 35 °C increased the rate of strain release and also the total percent strain released at 96 hours. In developing ‘Hedelfinger’ sweet cherry fruit, there was essentially no elastic strain in the exocarp at 45 days after full bloom (DAFB). Thereafter, significant elastic strain developed, reaching a maximum of 47.6% ± 2.5% at 87 DAFB. The effect of exocarp cell turgor on strain in the ES (evidenced by the difference in the reversible strain between ES with and without turgor) was closely and positively related to the relative area growth rate of the skin (r2 = 0.957). Strain release peaked at ≈59 DAFB, and there was no effect of turgor on strain release in mature fruit. Our data demonstrated the following: 1) the exocarp is a viscoelastic material composite; 2) at maturity, plastic and elastic strain components make up 66% and 34% of the total percent strain, respectively; 3) elastic strain in the exocarp increases during Stage III development; and 4) the strain in the exocarp is unaffected by strain in the CM. Thus, the epidermis and hypodermis layers must represent the main, load-bearing structure in sweet cherry fruit with the cuticle making a mechanically insignificant contribution.

scholarly journals Studies on Water Transport through the Sweet Cherry Fruit Surface: VIII. Effect of Selected Cations on Water Uptake and Fruit Cracking

2004 ◽  
Vol 129 (6) ◽  
pp. 781-788 ◽  
Author(s):  
Holger Weichert ◽  
Carina von Jagemann ◽  
Stefanie Peschel ◽  
Moritz Knoche ◽  
Dieter Neumann ◽  
...  
Keyword(s):  
Water Uptake ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Similar Data ◽  
Water Control ◽  
Mineral Salts ◽  
Simultaneous Treatment ◽  
Fruit Cracking ◽  
Trivalent Cations ◽  
Reduced Water

Water uptake through the exocarp of intact sweet cherry [Prunus avium (L.)] fruit was determined gravimetrically in an immersion assay (25 °C). Fruit with sealed pedicel/fruit juncture were incubated in water during the first interval (0 to 0.75 hour) and in 10 mm salt solutions of selected cations during the second (0.75 to 1.5 hours) and third interval (1.5 to 2.25 hours) of an experiment. Rates of water uptake (F) were calculated for first, second and third intervals (FI, FII and FIII, respectively) and salt effects indexed by the ratios FII/FI and FIII/FI. AgNO3 (FII/FI = 0.65), NaCl (0.70), BaCl2 (0.67), CdCl2 (0.69), CuCl2 (0.42), HgCl2 (0.58), and SrCl2 (0.69), and the salts of trivalent cations AlCl3 (0.50), EuCl3 (0.58), and FeCl3 (0.49), significantly decreased water uptake into mature `Sam' fruit as compared to the water control (0.87). KCl (0.82), NH4Cl (0.85), CaCl2 (0.75), MgCl2 (0.88), MnCl2 (0.81), and ZnCl2 (0.72) had no effect, LiCl (1.00) increased uptake. Similar data were obtained for FIII/FI. The effect of FeCl3 on water uptake was independent of the presence of CaCl2, AlCl3, or CuCl2, as sequential or simultaneous treatment with these salts reduced water uptake to the same extent as with FeCl3 alone. Increasing FeCl3 concentration up to 1 mm decreased uptake, higher concentrations had no further effect. FeCl3 and CaCl2 to a smaller extent decreased water uptake in developing `Regina' sweet cherry fruit (55 to 91 days after full bloom). FeCl3 had no significant effect on water uptake along the pedicel/fruit juncture, but markedly reduced uptake through the exocarp of all cultivars investigated (`Burlat', `Early Rivers', `Hedelfinger', `Knauffs', `Regina', `Sam', `Summit', and `Van'). Effects of CaCl2 on water uptake were limited to `Burlat', `Early Rivers', and `Hedelfinger'. CaCl2 and FeCl3 both decreased fruit cracking, but FeCl3 was more effective. The mode of action of mineral salts in decreasing water uptake and fruit cracking and their potential for field use are discussed.

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