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Cracking of cherry tomatoes in solution

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Tomato fruit cracking occurs both during ripening and after harvest. Cracked fruits cannot be marketed and the cracks form sites for fungal penetration and infection. An assay based on immersion of the fruit in water was developed to study factors involved in fruit cracking. Adding calcium to the water reduced cracking whereas chelating agents increased cracking. Mineral analysis of the fruit following calcium treatment demonstrated an increase in bound calcium, while CDTA reduced the amount of soluble calcium. Decrease in fruit weight associated with water loss during storage was correlated with a decrease in the cracking potential of the fruit. Conversely, ripening during storage resulted in an increase in the cracking potential. Immersion of the fruit in acidic phosphate or citrate buffers promoted cracking whereas neutral or basic buffers prevented cracking. The cracking potential of cherry tomatoes was high after morning harvest, and it declined at noon and was low after evening harvest. It is anticipated that this study will assist to evaluate positive or negative practices which may influence cracking of cherry tomatoes after harvest.
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Postharvest Biology and Technology 26 (2002) 305312
Cracking of cherry tomatoes in solution
Amnon Lichter
a,
*, Orit Dvir
a
, Elazar Fallik
a
, Shabtai Cohen
b
,
Rami Golan
b
, Zion Shemer
b
, Moshe Sagi
c
a
Department of Posthar6est Science of Fresh Produce,Institute for Technology and Storage of Agricultural Products,ARO,
The Volcani Center,P.O.Box
6
,Bet Dagan
50250
,Israel
b
Ramat Nege6Desert Agroresearch Center,D.N.Chalutza
85515
,Beer-She6a,P.O.Box
653
,Israel
c
The Institute of Applied Research,Ben Gurion Uni6ersity,Beer-She6a,P.O.Box
653
,Israel
Received 5 October 2001; accepted 18 April 2002
Abstract
Tomato fruit cracking occurs both during ripening and after harvest. Cracked fruits cannot be marketed and the
cracks form sites for fungal penetration and infection. An assay based on immersion of the fruit in water was
developed to study factors involved in fruit cracking. Adding calcium to the water reduced cracking whereas chelating
agents increased cracking. Mineral analysis of the fruit following calcium treatment demonstrated an increase in
bound calcium, while CDTA reduced the amount of soluble calcium. Decrease in fruit weight associated with water
loss during storage was correlated with a decrease in the cracking potential of the fruit. Conversely, ripening during
storage resulted in an increase in the cracking potential. Immersion of the fruit in acidic phosphate or citrate buffers
promoted cracking whereas neutral or basic buffers prevented cracking. The cracking potential of cherry tomatoes
was high after morning harvest, and it declined at noon and was low after evening harvest. It is anticipated that this
study will assist to evaluate positive or negative practices which may influence cracking of cherry tomatoes after
harvest. © 2002 Elsevier Science B.V. All rights reserved.
Keywords
:
Cherry tomatoes; Calcium; Cracking; Lycopersicon esculentum
www.elsevier.com/locate/postharvbio
1. Introduction
In nature, fruit cracking can be considered part
of the final developmental stage after ripening and
before seed dispersal. In commercial production,
cracked fruit cannot be marketed and the cracks
become sites for fungal penetration and infection.
One of the features of cracking after harvest is
that its incidence is erratic and monitoring and
control means are unsatisfactory. Thus, develop-
ment of methods to monitor fruit cracking would
serve to evaluate the cracking potential of various
genotypes and the effect of different horticultural
practices.
Fruit cracking in tomatoes (Peet, 1992) and
other fruits (Opara et al., 1997) suggests that
cracking is caused by several factors, mainly asso-
ciated with the water balance of the fruit. While
* Corresponding author. Tel.: +972-3-968-3684; fax: +
972-3-968-3622
E-mail address
:
vtlicht@volcani.agri.gov.il (A. Lichter).
0925-5214/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0925-5214(02)00061-3
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the water potential of the fruit is assumed to be
the driving force for cracking, cell, tissue and
organ structures confer resistance to pressure
(Voisey et al., 1970; Emmons and Scott, 1998).
One major factor in this complex system is the
content of extracellular calcium that crosslinks
pectin polymers to form the packed tissue (De-
marty et al., 1984). The pericarp tissue can be
regarded as a complex gel, which can swell or
shrink in proportion to the hydration status of the
gel and its calcium content (Tibbits et al., 1998).
A number of reports have addressed the effect of
calcium inltration on apple ripening and rm-
ness, e.g. Sams and Conway (1984), or the capa-
bility of calcium sprays to reduce rain-induced
cracking of sweet cherries (Glenn and Poovaiah,
1989; Yamamoto et al., 1992). Bangerth (1973)
reported that calcium inhibited cracking in toma-
toes immersed in solution.
The small size of cherry tomatoes allows labo-
ratory experiments to be conducted on a scale
that was not feasible for regular size tomatoes.
Our objective was to study factors such as calcium
and water content of the fruit, storage duration,
pH and harvest time, which may correlate to fruit
cracking in cherry tomatoes.
2. Materials and methods
2
.
1
.Fruit source and assay conditions
Tomatoes (Lycopersicon esculentum) cv. 819
and 139 (Hazera Genetics, Israel) were obtained
from commercial plots. The calyx was removed
from the fruit, the fruit were washed in distilled
water to remove dirt and were immersed in dis-
tilled water or one of the various solutions, as
indicated. The standard immersion period was 18
h at room temperature and the cracking index
was scored immediately.
2
.
2
.Materials
Chemicals were purchased from Sigma (St.
Lois, MO). Water for preparation of all solutions
and fruit immersion was puried by a single step
standard ion exchanger column (Zelion, Israel).
The pH of CDTA (1,2-cyclohexylenedinitrilote-
traacetic acid) or EDTA (ethylenediaminete-
traacetic acid) was adjusted to 7 with NaOH.
Sodium carbonate and sodium hydrogen bicar-
bonate (100 mM, 65:35, v:v) were used for prepa-
ration of a buffer with pH 10.3. Potassium
phosphate buffer at pH 7.2 was prepared by
mixing stock solutions of the monobasic and
dibasic salts (100 mM, 72:28, v:v). Acidic phos-
phate buffer (pH 3.0) was prepared by adding 1
ml of phosphoric acid to 100 mM of monobasic
potassium phosphate. A sodium acetate buffer at
pH 4.5 was prepared by mixing stock solutions of
the salt and glacial acetic acid (100 mM, 40:60,
v:v). These buffers were diluted 1:4 prior to ob-
taining the nal solution for immersion of tomato
fruit. Citric acid (0.1M) and disodium phosphate
(0.2 M) were mixed in the following volumetric
ratios (in ml) to obtain the desired pH: 462:38;
549:51; 637:63; 7 19:81; 8 1:99. They were
diluted with water at a ratio of 1:10 and the pH
was corrected after dilution.
2
.
3
.Cracking index
Cracking of individual fruit was evaluated ac-
cording to a severity index of 05. Cracks were
identied as: small, shorter than half the diameter
of the fruit and 1 mm or less in width; medium-
longer than half the diameter of the fruit and 24
mm wide; large, longer than half the diameter and
510 mm wide. The index was: 0, no cracks; 1, 1
small crack; 2- 2 small cracks or 1 medium sized
crack; 3-a complex of small and medium cracks.
4-a large crack alone or in combination with
smaller cracks; 5-fruit shape completely distorted
by cracks. In spite of the apparent complexity,
inexperienced personnel could generate repro-
ducible results after short training.
The cumulative severity index (I
s
) for each
replication was multiplied by two if the replica-
tion size was ten fruit, yielding a cracking index
on a scale of 0100. For example, for a replica-
tion of ten fruit that were assigned an I
s
of ve the
calculated index would be 100. Each treatment
consisted of 20 fruit in four replications. Tabu-
lated data or histograms (except for mineral anal-
ysis) were statistically analysis using Duncans
A.Lichter et al.
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307
multiple range test (DMRT) at P]0.95. Line
graphs are assigned with standard deviations.
Each type of experiment was performed at least
three times, except for these presented in Fig. 3,
which were performed once.
2
.
4
.The mineral composition of the fruit or
solutions
The mineral composition of tomato fruit was
determined by atomic emission spectrophotome-
try (ICP-inductively coupled plasma, at the Fac-
ulty of Agriculture, Rehovot, Israel). The mineral
composition of each solution in which fruit were
immersed was determined using 1 ml of solution
for each replicate. The soluble mineral content of
fruit was determined for 5 g of tomato pericarp
(including the peel and excluding the gel and
seeds). Five ml of water were added to the tissue
in a 50-ml polypropylene centrifuge tube. The
tissue was homogenized for 30 s with a Polytron
homogenizer (10 mm wide), the homogenate was
centrifuged for 10 min at 10 000×gand 1 ml of
the supernatant was used for analysis. The total
mineral content of the fruit was measured by
drying 58 g of the tissue in an oven at 90 °Cfor
24 h and determining the recovery of dry matter,
of which 100 mg were used for mineral analysis.
The concentrations of the minerals in the solution
were calculated by multiplying the measured con-
centration (mg/l) by the dilution factor (52) di-
vided by the molecular weight of the mineral. The
soluble mineral content was calculated by multi-
plying the measured concentration (mg/l) by the
dilution factor (26) divided by the molecular
weight of the mineral. Total mineral content, on a
gram fresh weight basis, was calculated by multi-
plying the measured concentration of the mineral
(mg/l) by a factor of 2.5 which accounts for the
percentage dry matter divided by the dry weight
(0.1 g) and 100, divided by the molecular weight
of the mineral.
3. Results
Study of fruit cracking in cherry tomatoes
would benet from an assay that would induce
cracking and facilitate evaluation of the effect of
different treatments. It was assumed that immer-
sion of tomato fruit in water would lead to crack-
ing. When fruit that had been stored at 12 °C for
6 days were immersed in distilled water for 20 h,
77% of the fruit cracked, compared with 5%
cracking in tap water. These results indicated that
tap water contained minerals that reduce the
cracking potential, with calcium being the promi-
nent factor. The results shown in Fig. 1 support
this hypothesis: immersion of the fruit in 25 mM
calcium chloride reduced the cracking index to
one-third of that of the control (Fig. 1a). Similar
results were obtained for calcium nitrate (not
shown). Furthermore, CDTA and EDTA, both of
which are chelators of divalent cations, induced
Fig. 1. The effect of calcium and calcium chelators on cracking of tomato fruit (A) and the effect of different solutes (B). Tomato
fruit (cv. 819) were immersed for 18 h in solutions containing the specied compounds in two separate experiments. Cracking was
quantied by measuring the number of cracked fruit multiplied by the cracking severity index. Each treatment was performed in four
replicates with 20 fruit per replicate. Cracking index was calculated and was analyzed using DMRT at P]0.95.
A.Lichter et al.
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26 (2002) 305312
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Fig. 2. Calcium content of cherry tomatoes after treatments.
The mineral compositions of the fruit was determined by ICP
analysis. Soluble minerals were obtained by homogenization of
tissue in water followed by clearing cellular debris by centrifu-
gation. Total mineral content was obtained from dried matter.
The solutions in which the fruit were immersed were also
assayed (except control fruit). Four replicates per treatment
were assayed and standard deviations were added for each bar.
fruit immersed in water. At both stages calcium
was very effective in eliminating cracking. Thus,
cracking of fruit of cv. 139 in solution was also
responsive to calcium. In spite of the pronounced
effect of calcium demonstrated in Figs. 1 and 3, in
some experiments calcium did not suppress crack-
ing (data not shown), suggesting the involvement
of other dominant factors.
The effect of fruit maturity was further evalu-
ated on fruit of cv. 819 harvested as bunches,
which were separated into green, red and interme-
diate fruit color. Fruit of the three groups were
immersed in water and the cracking index of red
fruit was 6195 compared with a value of 15 915
for fruit that did not develop full color, or no
cracking for green fruit. In this experiment, whole
bunches containing red fruit were dipped in water,
resulting in no cracking compared with the high
cracking of the detached fruit.
Cracking of fruit in solution started within
several hours of immersion and it was faster in
solution containing 2.5 mM CDTA (data not
shown). Cracking in solution was also affected by
fruit and solution temperature: for example, a
cracking index of 6.994.5 was recorded after
immersion of fruit with internal temperature of
12 °C in a solution with a temperature of 24 °C,
compared with a score of 24.399.7 when the
temperature of the fruit was 24 °C and the solu-
tion was at 4 °C.
cracking (Fig. 1a). Another divalent cation, mag-
nesium chloride (Fig. 1b) applied at a similar
concentration as calcium chloride (25 mM) did
not reduce cracking signicantly. Similarly,
sodium chloride, manitol (Fig. 1b) and ferrous
chloride (data not shown) did not affect cracking,
demonstrating that the prevention of cracking
was not mediated by an osmotic effect.
The mineral composition of fruit treated with
calcium or CDTA was analyzed to examine the
amount of calcium in fruit following treatments
(Fig. 2). Calcium analysis revealed that CDTA
reduced the amount of calcium, mainly from the
soluble fraction and calcium leakage to the solu-
tion was apparent. The calcium solution increased
both the soluble and total calcium concentration
of the fruit.
The effects of calcium and CDTA were also
tested on cv. 139, the major commercial cherry
tomato cultivar in Israel. This cultivar has smaller
fruit with thicker peel compared with fruit of cv.
819. Fruit of cv. 139 were obtained at the breaker
and orange maturity stages and they were stored
at 12 °C. Assays were performed after 4 or 13
days, and fruit ripened during this period. The
assay performed after 4 days showed that calcium
suppressed cracking to zero and CDTA induced
cracking to an index of ten (Fig. 3). After 13 days
at 12 °C cracking was higher in the three treat-
ments and the greatest increase was recorded for
Fig. 3. Cracking at two ripening stages of cherry tomato cv.
139. Fruit were obtained at the breaker stage and assayed 4 or
13 days after harvest. After 13 days at 12 °C, the fruit became
red and ripe. Fruits were immersed in distilled water, CDTA
(2.5 mM) or CaCl
2
(25 mM). Cracking index was calculated
and was analyzed using DMRT at P]0.95.
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Posthar6est Biology and Technology
26 (2002) 305312
309
Fig. 4. The kinetics of cracking and weight loss during storage
at 12 or 24 °C. Cherry tomato fruit were weighed and stored
in punnets at 12 or 24 °C for 6 days. Ten fruit in each of the
four replications were weighed and immersed in distilled water
at the specied times. A. The calculated cracking index for
both treatments. B. The average weight loss of the fruit (%)
and the calculated ratio between the cracking indices at 12 and
24 °C (dotted line). Error bars represent standard deviation.
cracking potential was annulled. Fruit stored at
12 °C lost only 2% of their weight within that
period and had a similar cracking score at the
initial and nal time points. The ratio of crack-
ingat12and24°C created a linear curve (Fig.
4b, dotted line).
The pathway by which the solution enters the
fruit can be either the cuticle, or the scar of the
pedicel or both. However, sealing the scar with
silicone grease did not reduce cracking (data not
shown). Wounding of fruit stored for one week
at 12 °C with a needle prior to brief dipping in
water and passive drying resulted in cracking of
the wounded fruit, which was apparent after 3 h
and increased by 20 h. This result was not re-
producible in two other experiments in which
freshly harvested fruits were used, suggesting
that the sensitivity to wound-induced cracking
depended on additional factors.
The pH of the solution used for dipping the
fruits was tested because evidence in the litera-
ture suggested that phosphoric acid promoted
cracking (Bangerth, 1973). The acidic phosphate
buffer described in Table 1 promoted cracking
while acetate at pH 4.5 did not have a marked
effect. In contrast, neutral phosphate or basic
carbonate buffers eliminated cracking. To fur-
ther study the effect of pH on cracking, solu-
tions made of citrate-phosphate buffer were
used. The results in Fig. 5 conrm that pH
Table 1
The effect of different buffers on cracking of cherry tomatoes
cv. 819
DMRT
a
Buffers
a
ph Cracking index
0.390.4NaHCO
3
+Na
2
CO
3
d10.4
KH
2
PO
4
+K
2
HPO
4
7.2 0 d
Sodium acetate
b
4.5 13.9912.1 c
a71.397.6KH
2
PO
4
c
3.0
27.793.3H
2
Ob
a
DMRT was performed on four replications at P]0.95.
b
The pH of sodium acetate was adjusted to 4.5 with acetic
acid.
c
ThepHofKH
2
PO
4
was adjusted to 3.0 with phosphoric
acid.
The changes of the cracking potential during
storage were evaluated by storing the fruit at
either 12 or 24 °C (8090% and 50 60% rela-
tive humidity, respectively) and monitoring
weight loss and the cracking index. After 1 day
of incubation at 12 or 24 °C, the differences in
the cracking index or in weight loss became ap-
parent (Fig. 4). Fruit stored at 24 °C lost al-
most 8% of their weight over 6 days and their
A.Lichter et al.
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Posthar6est Biology and Technology
26 (2002) 305312
310
Fig. 5. The effect of the pH of the immersion solution on
cracking of cherry tomatoes. Fruit (cv. 819) were immersed in
solutions made of citrate-phosphate buffer adjusted to the
specied pH. Experiments were conducted with four replica-
tions of 20 fruit per replicate. Error bars represent standard
deviation.
4. Discussion
The natural level of cracking in tomatoes after
harvest is not high or consistent enough to permit
continuous investigation. Induction of cracking
by immersion has been described previously for
tomatoes (Bangerth, 1973), sweet cherries (Glenn
and Poovaiah, 1989), and bell peppers (Aloni et
al., 1999). To assay induced cracking, one could
either use the percentage of cracked fruit or an
index that will take into account the severity of
cracking. The later possibility was chosen, mainly
because calcium not only reduced the number of
cracked fruit but had also a strong positive im-
pact on the severity of cracking, whereas CDTA
had a negative effect.
Prolonged incubation of tomato in calcium so-
lution resulted in an increase in the calcium con-
tent of the apoplast, leading to a decrease in
cracking. In apples, the major effect of calcium
dips was increased rmness, e.g. Bangerth et al.,
1972). CDTA induced fruit cracking by depleting
calcium from the apoplast, resulting in pectin
disassembly (Bangerth, 1973; Glenn and Poova-
iah, 1989). Occasionally, calcium did not suppress
cracking in solution, suggesting the counter 34-
fold affect of a dominant factor. Short exposure
to high doses of calcium did not affect cracking,
suggesting that the process depended on diffusion
of the ion into the fruit apoplast.
Another factor that inuences the structure of
of pectin is acidity. Lowering of the pH of the
tissue can dissociate calcium from pectin due to
cation exchange with protons. As a result the
pectic gel can swell (Tibbits et al. 1998). Another
mechanism that can contribute to gel swelling is
the increased activity of polygalacturonases at an
acidic pH, activity which is suppressed by calcium
and stimulated by EDTA (Chun and Huber,
1998). The positive effect of neutral or basic
buffers in prevention of cracking was dominant
over the effect of calcium and the combined effect
of calcium in neutral or basic buffers was domi-
nant in occasions that cracking was not annulled
by either of the components. It should be noted in
this respect that calcium chloride solution is acidic
and the CDTA solution was neutralized prior to
application.
plays a central role in determining cracking in
solution.
It was assumed that water accumulation in the
fruit during the night will increase the cracking
potential of the fruit. This assumption was cor-
roborated in experiments in which fruit of cv. 496
were harvested early in the morning, at noon or in
the evening (Fig. 6). It is shown that the cracking
potential was higher with the morning or the
noon harvests, respectively, compared with the
evening harvest.
Fig. 6. The cracking potential of cherry tomatoes after morn-
ing, noon or evening harvests. Fruit of cv. 496 were harvested
in a commercial plot grown under net. Fruit were harvested at
the specied times and were immersed in water in the morning
after the harvest. Results are the average of four replications
of 25 fruit per replicate. Cracking index was calculated and
was analyzed using DMRT at P]0.95
A.Lichter et al.
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Posthar6est Biology and Technology
26 (2002) 305312
311
Two contradictory processes are taking part
during fruit maturation and storage of cherry
tomatoes. Water loss results in reduced cracking
potential, because the turgor pressure within the
fruit is the major driving force for cracking (Peet,
1992). On the other hand, the progress of ripening
before or during storage increases the cracking
potential, most likely due to enzymatic cell wall
metabolism.
Combinations of conditions, such as early
morning harvest on colder and cloudy days, un-
sorted bruises in the skin and high humidity dur-
ing storage, may result in erratic fruit cracking
and subsequent decay. The increased cracking
potential of tomato fruit harvested early in the
morning is likely to result from the same mecha-
nism that causes apples to be more sensitive to
subsequent bruising in the morning compared to a
with noon harvest (Viljoen et al., 1996).
It was argued that the model of dipping fruits
in solution might not represent natural cracking
(Peet, 1992). This is because evapotranspiration
disposes most of the water inow from fruit at-
tached to the vine. On the other hand, no sub-
stantial water inows occur in detached fruit,
which are stored at optimal conditions. In con-
trast, induced cracking in solution results from
osmotic inow of water through the skin. Al-
though immersion of cherry tomatoes in aqueous
solutions may not be a perfect model to study
fruit cracking, it is justied because it is respon-
sive to some of the physiological parameters that
may inuence natural cracking. These factors in-
clude the water content of the fruit prior to
harvest, storage conditions, calcium content and
harvesting time. Water inow through the skin
should increase if fruit are bruised or suffer from
micro-cracks. Water inow should also increase if
the calcium content in the pericarp is such that it
will allow for swelling to occur. Similarly, in-
creased water content in the fruit prior to immer-
sion, would require less osmotic pressure to cause
the peel to crack. Situations of water inow
through the skin may be encountered during
morning condensation on cold fruit prior to har-
vest, postharvest washing procedures, extreme hu-
midity during storage (e.g. sea transportation)
and disruption of the cold-chain. Finally, articial
water accumulation in the fruit during immersion
can help to identify structural defects in the fruit,
such as thin or non-elastic peel and non-symmet-
ric pericarp swelling.
If a correlation between induced cracking in
solution and postharvest cracking is established,
this assay can be developed as a monitoring tool
to assess the cracking potential of specic fruit
lots prior to storage or export. Once high cracking
is encountered, fruit pallets may be withheld at
ambient temperature before entering cold storage.
Further use of this technique may be in breeding
programs for selection of cracking-tolerant vari-
eties or in identication of preventive horticul-
tural treatments, such as avoidance of harvest in
the morning under sensitive conditions, or cal-
cium sprays that will prevent cracking.
Acknowledgements
This paper is a contribution from the Agricul-
tural Research Organization, the Volcani Center,
Bet Dagan, Israel, No. 411/01. This research was
supported by grant No. 402-0271 from the Chief
Scientist, the Ministry of Agriculture & Rural
Development.
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... Singh et al. (2006) also reported similarly as sudden change in soil moisture causes the moisture stress, which affects the fruit development adversely and leads to fruit cracking. The rapid absorption of water when irrigation is resumed to severely stressed fruit leads to cracking of the skin as water is diverted to the aril and greater stress is placed on the water-deficient skin (Galindo et al., 2014;Lichter et al., 2002). It has also been suggested that asymmetrical stretching of the skin occurs as the aril fills with water. ...
... Studies supported the fact that fruit cracking in pomegranate mainly have occurred due to imbalance of soil moisture and plant water status especially during latter stages of fruit growth and development as pomegranate is very sensitive to these variations (El-Rhman, 2010; Galindo et al., 2014;Hepaksoi et al., 2000;Lichter et al., 2002;Singh et al., 2006). As high demand of water during fruit growth and development is to be met from leaf following sourcesink relationship (Hepaksoy et al., 2000), plant water gradient induces the process of water loss from plant either through fruit surface or canopy surface to atmosphere in soil-plant-atmosphere continuum and thus greatly influences water relations and hence lead to incidence of cracking in fruits. ...
... Several factors are associated with water balance that may lead to cracking. The water potential of the fruit produces the cracking force, and the cell wall and other structures must resist this pressure (Lichter et al., 2002). ...
Article
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Pomegranate (Punica granatum L.) is an economically important fruit crop of tropical and subtropical regions of the world. There has been enormous increase in area, production, and export worldwide over the past decades. But cracking of mature fruit is an important physiological disorder which causes great economic loss to pomegranate. As high losses as 65% have been reported in pomegranate. It is a general problem throughout its growing areas and among all varieties worldwide. Causes associated with fruit cracking may be improper irrigation, environmental factors, and nutritional deficiency, especially boron, calcium, and potash. Besides, it is also reported to be associated with high evapo-transpiration, low humidity, water imbalance, and sharp temperature fluctuation in day and night during fruit growth and development. The cracking is more evident when the fruits are at maturity stage. No single factor can be advocated as efficient enough in controlling fruit cracking. The behavior of fruit cracking in relation to internal fruit composition and quality characteristics, dynamics of water uptake, understanding on how water, gibberellins, abscisic acid, boron, calcium, and the cell wall biosynthesis interacts with fruit cracking, will offer a clearer insights in devising developmental strategies to reduce fruit cracking.
... In nature, fruit cracking manifests at the end of fruit development, that is, just after ripening and before seed dispersal (Lichter et al., 2002). It is a physiological disorder that affects the exocarp and the mesocarp (Yu et al., 2020) and can be distinguished from epidermis cracking, which is more superficial, including the cuticle and epidermal tissue. ...
... The water balance of fruits is associated with several factors that can generate cracks (Saei et al., 2014), where the water potential is the force that produces cracking, while the cell wall and other structures must withstand this pressure (Lichter et al., 2002). Thus, the biomechanical characteristics of the epidermis are crucial in maintaining internal pressure and resistance to fruit cracking (Saei et al., 2014). ...
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The objective of this review was to report on advances in environmental , cultural, and physiological aspects of fleshy fruit cracking that have reduced or avoided this disorder, which affects many fruit species. Cracking is a physiological disorder that limits the production and quality of fleshy fruits because it affects the exocarp and mesocarp, especially with climate change and variability. Fruit cracking is generated by external factors (agronomic and environmental) and internal factors, several of which require exhaustive study. The incidence of cracking varies widely according to climatic characteristics during fruit development, different fruit species and varieties , growth sites, and crop management. This physiological disorder is aggravated by increases in rain intensity, especially after a dry season or in areas with increased temperatures. Knowledge on causes of cracking has generated management strategies that involve genetic improvement, ecophysiological conditions, agronomic practices such as pruning, irrigation, and fertilization (mainly Ca, Mg, B, and K), applications of plant growth regulators, and use of plastic covers, etc. For several fruit trees, these strategies are effective, but in species such as the cape gooseberry, cracking remains without a full explanation or effective management.
... Fruit cracking is one of the most important physiological disorders in tomato production that often occur during the light-red ripening stage and is a major bottleneck limiting high-quality cultivation (Dominguez et al., 2012). When fruit is cracked, the water in the flesh is lost, and pathogens infiltrate along the fissures, which can quickly lead to rapid rot of the fruit and loss of commodity and consumption value, resulting in economic loss and waste of resources (Lichter et al., 2002). The tomato pericarp mainly consists of exocarp and mesocarp. ...
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Fruit cracking is one of the most common physiological disorders that causes fruit loss and reduces tomato fruit marketability and quality. In this study, a three-point bending extended finite element (XFEM) model including five parts: a loading probe, exocarp, mesocarp, pre-crack, and two rigid fixed support points was developed for investigating the cracking susceptibility of pericarp during fruit development and postharvest handling. During pericarp cracking simulation, a displacement load of the probe was applied over a cuboid pericarp sample to replace the increasing turgor pressure of mesocarp cells. The XFEM-based three-point bending model with average tissue mechanical data was found to be able to reproduce the probe loading force-pericarp deflection behavior and the crack propagation length-pericarp deflection behavior in the three-point bending test up to 6 mm tomato pericarp deflection deformation with an average relative error of about 7.8% and 5.2%, respectively. The XFEM model's crack propagation area and volume were affected by environmental temperature, exocarp and mesocarp thickness. Three multiple linear regression mathematical models were established for quantitatively predicting the tomato pericarp cracking susceptibility. It was found that the factors affecting the cracking susceptibility of pericarp in descending order include exocarp thickness, pericarp deflection, mesocarp thickness, and temperature. This study provides a new approach to quantitatively predict the cracking susceptibility of tomato pericarp, especially in the breeding industry for reversely and quickly locating the fruit anti-cracking gene.
... Concentric cracking is severe in fruits exposed to sun as compared to fruits covered with foliage. Lichter et al (2002) found that cherry tomatoes harvested in evening are less prone to fruit cracking. The incidence of cracking varies with cultivars (Abbot et al 1986, Mullins and Straw 1992, Maroto et al 1995, Fernandez-Munoz et al 1995, Sperry et al 1996. ...
... The incidence of cracking in some landraces in the current study was >30%, underlining the importance of this disorder for the profitability of long-shelf-life varieties. The incidence of cracking can be either genetically or environmentally controlled [42,[72][73][74], and the main agronomic strategy to prevent cracking is to use resistant cultivars. Several environmental conditions (rainfall, humidity) and management practices (irrigation, fertilization, balance between reproductive and vegetative organs, harvesting at early stages) have been described as affecting cracking incidence in several species, including tomatoes [42,72], cherries (Prunus avium L.) [75], or apples (Malus domestica L.) [76], among others [77]. ...
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The individual effects of biotic and abiotic factors on tomatoes have been widely reported. However, under commercial conditions, multiple interactions between factors occur, masking or even changing the direction of their effects in some cases. Here we report a comprehensive analysis of preharvest factors affecting yield, quality (soluble solids content, fruit color, and firmness), and shelf-life of long-shelf-life Mediterranean varieties of tomatoes. We studied five long-shelf-life genotypes under 16 growing environments, including tunnel and open-air systems and suboptimal to excessive fertigation (22–142% crop evapotranspiration). The results enabled us to classify traits into three groups according to the importance of the contributions of different types of factors: mainly genotype (ripening earliness and firmness), genotype plus environment (yield, fruit weight, water-use efficiency (WUE)), or genotype plus environment plus the interaction between genotype and environment (cracking, soluble solids content, and shelf-life). Under similar management practices, open-air conditions optimized yields, and high fertigation doses improved yield and marketability (firmness), but reduced quality (redness and soluble solids content). WUE was maximized under low-input cropping systems (comparable to traditional agrosystems), and the balance between WUE and yield was optimized when fertigation was adjusted to the requirements of the crop. Shelf-life was negatively correlated with high-yielding environments, and day–night amplitude in relative humidity was strongly correlated with the incidence of fruit cracking. The present study sheds light on the contributions of environment and management practices on tomato yield and quality, and provides a basis on which to select better management practices for the novel commercial group of European long-shelf-life tomato landraces.
... Rain cracking is a critical production problem for many fleshy fruitcrops, especially when rainfall occurs during the later stages of fruit maturation. Sweet cherry and grape are prominent examples of rain-susceptible fruitcrops but many others are also rain-susceptible including: tomatoes, plums, blueberries, currants and gooseberries (Mrozek and Burkhardt 1973;Lichter et al. 2002;. The economic losses associated with rain cracking in this diversity of fruitcrop species range from a minor impairment of fruit quality due to shallow cracks within the cuticle (microcracks) that can trigger russeting ) and increase the incidence of fruit rots (Borve et al. 2000) and increase the rate of postharvest water loss (Maguire et al. 1999), to deep cracks (macrocracks) that propagate down through the cell layers of the skin into the flesh opening the way for massive invasion by insects and rots. ...
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Main conclusion During fruit development, cell wall deposition rate decreases and cell wall swelling increases. The cell wall swelling pressure is very low relative to the fruit’s highly negative osmotic potential. Abstract Rain cracking of sweet cherry fruit is preceded by the swelling of the cell walls. Cell wall swelling decreases both the cell: cell adhesion and the cell wall fracture force. Rain cracking susceptibility increases during fruit development. The objectives were to relate developmental changes in cell wall swelling to compositional changes taking place in the cell wall. During fruit development, total mass of cell wall, of pectins and of hemicelluloses increases, but total mass of cellulose remains constant. The mass of these cell wall fractions increases at a lower rate than the fruit fresh mass—particularly during stage II and early stage III. During stage III, on a whole-fruit basis, the HCl-soluble pectin fraction, followed by the water-soluble pectin fraction, the NaOH-soluble pectin fraction and the oxalate-soluble pectin fraction all increase. At maturity, just the HCl-soluble pectin decreases. Cell wall swelling increases during stages I and II of fruit development, with little change thereafter. This was indexed by light microscopy of skin sections following turgor release, and by determinations of the swelling capacity, water holding capacity and water retention capacity. The increase in cell wall swelling during development was due primarily to increases in NaOH-soluble pectins. The in vitro swelling of cell wall extracts depends on the applied pressure. The swelling pressure of the alcohol-insoluble residue is low throughout development and surprisingly similar across different cell wall fractions. Thus, swelling pressure does not contribute significantly to fruit water potential.
... 또한 칼슘은 식물 조직 및 과일에 생리학적으로 중요한 역할을 하며 (Winkler and Knoche, 2019) 칼슘을 분무하면 열 과가 줄어드는 효과가 있다 (Verner, 1938). 체리 '0900지랏'에 수확 전 염화칼슘을 엽면살포하여 과일의 열과를 줄이고 과피 의 탄력성을 증진 (Erogul, 2014) 시켰고, 체리토마토에서는 수확 후 칼슘 도포로 열과를 예방하는데 긍정적인 효과가 있는 것 으로 보고되었다 (Lichter et al., 2002). 포도에서 칼슘은 과일의 경도를 향상시킬 뿐만 아니라 동록을 감소시키는 효과가 있고 (Antunes et al., 2004), 키위프루트 '헤이워드' (Gerasopoulos et al., 1996), 복숭아 '얼리웰링' (Gayed et al., 2017), 딸기 '엘 산타' (Wójcik et al., 2003), 체리 '0900지랏' (Ekinci et al., 2016) (Kumar, 2000), 키토산을 과일에 처리하면 과피에 반투과성 필름 형성으로 호흡과 증산을 억제하여 저장성을 향상시키고 (Bautista-Baños et al., 2006), 감모율을 줄여 과일의 품질을 향상시킨다 (Petriccione et al., 2015). ...
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The post‐harvest decay of durian (Durio zibethinus Murr.) increases rapidly when the storage time is extended, which seriously limits the commercial value. In this research, the effects of appropriate periodical SO2 fumigation and different CO2‐enriched atmospheres (3% O2 + 10%~13%, 14%~17% or 18%~21% CO2) on the storage quality of durian stored at 14 °C were investigated. Results showed that SO2 fumigation in combination with enriched CO2 atmosphere (14%~17%) could maintain firmness (16.37 N), retard weight loss (10.24%), reduce decay rate (11%), inhibit the production of ethylene (9.2 μL·kg‐1h‐1) and malondialdehyde (12.10 μmol·g‐1). Moreover, the treatment consolidated the disease resistance of durian by: firstly, enhancing peroxidase (POD) and catalase (CAT) activities; and secondly, restraining polyphenol oxidase (PPO) activity, which helped to maintain the cell integrity structures. More importantly, this treatment retained a high sensory score (41.35) and extended the storage life up to 60 d. Therefore, a combination of 1500 mg·L‐1 SO2 fumigation and controlled atmosphere storage (3% O2 + 14%~17% CO2) was the more effective method to delay maturation and senescence and improve storage quality of durian.
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Fruit cracking is a common physiological disorder in many fruit species. Jujube (Ziziphus jujuba Mill.) is an economically valuable fruit in which fruit cracking seriously affects fruit yield and quality and causes significant economic losses. To elucidate cracking-related molecular mechanisms, the cracking-susceptible cultivars ‘Cuizaohong’ and ‘Jinsixiaozao’ and the cracking-resistant cultivar ‘Muzao’ were selected, and comparative transcriptome analyses of cracking and non-cracking ‘Cuizaohong’ (CC and NC), cracking and non-cracking ‘Jinsixiaozao’ (CJ and NJ), and non-cracking ‘Muzao’ (NM) were conducted. A total of 131 differentially expressed genes (DEGs) were common to the CC vs. NC and CJ vs. NJ comparisons. To avoid passive processes after fruit cracking, we also mainly focused on the 225 gradually downregulated DEGs in the CJ, NJ, and NM samples. The functional annotation of the candidate DEGs revealed that 61 genes related to calcium, the cell wall, the cuticle structure, hormone metabolism, starch/sucrose metabolism, transcription factors, and water transport were highly expressed in cracking fruits. We propose that expression-level changes in these genes might increase the turgor pressure and weaken mechanical properties, ultimately leading to jujube fruit cracking. These results may serve as a rich genetic resource for future investigations on fruit cracking mechanisms in jujube and in other fruit species.
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Fruit cracking is a physiological disorder in many plant species that leads to severe economic losses. The aim of this study was to investigate the effect of calcium on fruit cracking and explore the underlying mechanisms. We studied the effect of exogenous calcium on grape berry cracking, calcium absorbance and distribution, and cell wall metabolism in the cracking-susceptible cultivar 'Xiangfei'. Calcium significantly reduced the frequency of fruit cracking, increased the break force of the berry skin, and stimulated storage of calcium. In addition, calcium increased the content of protopectin and inhibited the increase in content of water-soluble pectin, by regulating the transcription and activities of enzymes associated with cell wall metabolism. Taken together, the results indicated that dipping grape berries in calcium solution is effective in preventing fruit cracking by stimulating calcium uptake, inhibiting cell wall disassembly, and promoting cell wall strengthening.
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Fruit anatomy and ultrastructure associated with cuticle cracking (CC) were compared for five cultigens (genotypes) of tomato. Cultigens resistant to CC had combined epidermal and cuticle (epicarp) layers significantly thicker (10.38-11.37 μm) than susceptible cultigens (6.45-7.76 μm). Thickness of the epicarp was negatively correlated (r = -0.43) with light reflectance and can be indirectly estimated by measuring light reflectance of the fruit. Plants producing globeshaped fruit or jointless pedicels tended to have higher incidences of CC (more fruit affected) than did plants producing fiat-round fruit or jointed pedicels, respectively, but this trend was significant for only one of four segregating populations for each trait. As fruit size increased, incidence of CC significantly increased, accounting for 16%-33% of the variance in incidence of CC over two harvests. Yield and number of fruit harvested accounted for <10% of the variance in incidence. Severity of CC (surface area of fruit showing CC) was less affected by fruit size, number of fruit harvested, and yield than was incidence of CC.
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The environmental and physiological causes of cracking or splitting of soft fruits and citrus as they ripen are not well understood. This paper explores factors contributing to radial cracking in tomatoes, gives suggestions for prevention of cracking, and suggests directions for future research. Fruit cracking occurs when there is a rapid net influx of water and solutes into the fruit at the same time that ripening or other factors reduce the strength and elasticity of the tomato skin. In the field, high soil moisture tensions suddenly lowered by irrigation or rains are the most frequent cause of fruit cracking. Low soil moisture tensions reduce the tensile strength of the skin and increase root pressure. In addition, during rain or overhead irrigation, water penetrates into the fruit through minute cracks or through the corky tissue around the stem scar. Increases in fruit temperature raise gas and hydrostatic pressures of the pulp on the skin, resulting in immediate cracking in ripe fruit or delayed cracking in green fruit. The delayed cracking occurs later in the ripening process when minute cracks expand to become visible. High light intensity may have a role in increasing cracking apart from its association with high temperatures. Under high light conditions, fruit soluble solids and fruit growth rates are higher. Both of these factors are sometimes associated with increased cracking. Anatomical characteristics of crack-susceptible cultivars are: 1) large fruit size, 2) low skin tensile strength and/or low skin extensibility at the turning to the pink stage of ripeness, 3) thin skin, 4) thin pericarp, 5) shallow cutin penetration, 6) few fruits per plant, and 7) fruit not shaded by foliage. Following cultural practices that result in uniform and relatively slow fruit growth offers some protection against fruit cracking. These practices include maintenance of constant soil moisture and good Ca nutrition, along with keeping irrigation on the low side. Cultural practices that reduce diurnal fruit temperature changes also may reduce cracking. In the field, these practices include maintaining vegetative cover. Greenhouse growers should maintain minimal day/night temperature differences and increase temperatures gradually from nighttime to daytime levels. For both field and greenhouse tomato growers, harvesting before the pink stage of ripeness and selection of crack-resistant cultivars probably offers the best protection against cracking. Areas for future research include developing environmental models to predict cracking and exploring the use of Ca and gibberellic acid (GA) sprays to prevent cracking.
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The effects of spraying sweet cherry trees with calcium nitrate and naphthalene acetic acid (NAA) and their combination during the rainy season were investigated.1. Spraying with 0.5% calcium nitrate solution significantly reduced the cracking index of 'Napoleon' sweet cherries and the percentage of cracked fruits under rain without any visble residue and damage from the chemicals.2. Application of NAA at 0.5, 1 and 2 ppm on 'Satohnishiki' reduced the cracking index and the percentages of cracked fruits to 15 to 30% and 13 to 40% of the control, respectively. In 'Napoleon' sprayed with Ca (NO3)2 and NAA, the cracking index and % cracked fruit decreased to 20 to 38% and 26 to 66%, respectively.3. Spraying with the combination of the 2 reagents more effectively reduced the cracking of 'Napoleon' than did either reagents as a single spray; and the minimum value of the index and the % cracked fruits was about one eighth of the control.