Effect of Harvesting Method and Calcium on Post Harvest Physiology of Tomato

Nepal Agric. Res. J. Vol. 7, 2006
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Effect of Harvesting Method and Calcium on Post Harvest Physiology of
Tomato1
Dhruba R. Bhattarai2 and Durga M. Gautam3
2 Horticulture Research Division-NARC, Khumaltar
3 Institute of Agriculture and Animal Science, Rampur, Chitwan
ABSTRACT
An experiment was conducted in Institute of Agriculture and Animal Science, Rampur, Chitwan
during 2003 to find out the effect of harvesting method and calcium chloride treatment on post-
harvest physiology of tomato. Tomato (Hybrid Gootya) fruits with stalk and without stalk were
harvested at breaker stage and dipped in distilled water and different concentrations of calcium
chloride viz. 0.25%, 0.50%, 0.75% and 1% for fifteen minutes. Fruit were then air-dried and
stored at ambient condition (24 ± 30 C and 70 ± 5 % RH). Among the tested treatments the least
cumulative physiological weight loss (12.14%) was exhibited by 1% calcium chloride. The shelf
life of tomato fruits was significantly affected by harvesting method and calcium treatment.
Tomato fruit harvested with stalk had higher shelf-life (15 days) as compared to those harvested
without stalk (12.93 days) irrespective to calcium chloride application. The maximum shelf life
was noticed in 1% calcium chloride treated fruits (16.50 days) followed by 0.75% calcium
chloride treated fruits (16.17 days).
Key words: Calcium chloride, physiological weight loss, shell life, tomato
INTRODUCTION
Tomato is highly perishable and cannot be stored for longer duration. Due to perishability, farmers are
losing a bulk of produce each year. Bistha (2002) have reported upto 50% post-harvest loss of tomato in
Nepal. Calcium is relatively divalent cation that readily enters the apoplast and is bound in
exchangeable from to cell wall and exterior surface of plasma membrane. Nontoxic even at high
concentrations it serves as a detoxifying agent. In the cell walls calcium serves as a binding agent in the
form of calcium pectates. Calcium has received considerable attention in recent years due to its
desirable effects; particularly it can delay ripening and senescence, reduce respiration, extend shelf life
and reduce the physiological disorders (Sharma et al 1996).
The shelf life is also affected by stalk. Pathak and Shrivastava (1969) have reported the stalk of fruits
showed less infection than without stalk fruit upon ripening. Similarly Singh et al (1993) have reported
longer shelf life and better marketability of tomatoes having a small pedicel along with calyx.
Therefore, this investigation was undertaken to identify the appropriate dose of calcium chloride and
compare the storage behavior of tomato harvested with and without stalk.
MATERIALS AND METHODS
This experiment was conducted during 2003 in Institute of Agriculture and Animal Science, Rampur,
Chitwan under Completely Randomized Design (CRD) with three replications. Tomato (Hybrid
Gootya) fruits with stalk and without stalk at breaker stage were harvested from farmer field at

1 A part of MSc thesis submitted by the first author to the Institute of Agriculture and Animal Science, Rampur,
Chitwan, Nepal in 2003.

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Bhandara, Chitwan and brought to IAAS, Rampur. Fruits were dipped in distilled water and different
concentrations of calcium chloride viz. 0.25%, 0.50%, 0.75% and 1% for fifteen minutes. The fruits
were then air-dried and 1.5 kg of fruits was kept on open tray. Each tray was considered as one
treatment and ten fruits were numbered (1 to 10) individually for determining physiological weight loss.
Physiological weight loss (%) was determined by following formula:
Weight loss (%) = [(Initial weight – Final weight) / Initial weight] 100

Titrable acidity was determined by titration method at red ripe stage. It was calculated by following
formula:
Titrable Acidity (%) = (NB x VB milliequivalent wt. of citric acid 100 d. f.) / Volume of sample
Where,
NB = Normality of base, VB = Volume of the base, d. f. = Dilution factor.
The total soluble solid (0 Brix) was determined by hand refractometer (Model: Erma Japan) in red ripe
stage of fruits and pH was measured by automatic pH meter.
RESULTS AND DISCUSSION
Physiological weight loss
Cumulative physiological weight loss of the fruits with respect to harvesting methods and calcium
chloride treatments is presented in Table 1. Harvesting method did not influence the weight loss of
tomato. Physiological weight loss after 10 days of storage ranged from 15.07 to 15.27%. On the other
hand, calcium chloride treatment significantly influenced the physiological weight loss of the fruits right
after second days of storage and subsequently afterwards. After 2 days of storage, controlled fruits
exhibited 4.2% PWL which was significantly higher than calcium treated fruits.
Table 1. Cumulative physiological weight loss (%) of tomato fruits at various days after storage (DAS) as
affected by harvesting methods and calcium chloride treatment at ambient condition (24 ± 30 C and 70
± 5% RH)
Harvest method
2 DAS
4 DAS
6 DAS
8 DAS
10 DAS
Without stalk
3.01
6.10
8.36
11.00
15.27
With stalk
2.97
6.04
8.38
10.45
15.07
SEM
0.15
0.29
0.31
0.47
0.41
CaCl2
Water
4.02
8.71
11.68
14.27
19.03
0.25%
3.21
6.13
8.56
12.06
17.02
0.50%
2.89
5.33
7.85
10.72
14.86
0.75%
2.25
4.81
6.93
8.25
12.80
1.00%
2.57
5.36
6.85
8.31
12.14
LSD (5%)
0.68
1.33
1.44
2.18
1.93
SEM
0.23
0.45
0.49
0.74
0.66
After 10 days of storage, the cumulative weight loss in 1.00, 0.75, 0.50 and 0.25% calcium treated fruits
was 12.14, 12.80, 144.86 and 17.02%, respectively as compared to 19.03% in controlled fruits.
Interaction effect between method of harvesting and calcium chloride treatment was non-significant.
Calcium is the important mineral constituent and it is the constituent of middle lamellae. Softening of
fruits is mainly due to weakening of middle lamellae during ripening. Calcium helps to bind

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polygalactonic acid each other and make the membrane strong and rigid. Calcium treatments have been
commercially applied in apple to increase the shelf life and reduce the post harvest disorders (Sharma et
al 1996). Thus, calcium might have delayed senescence and rate of respiration and transpiration in
tomato fruits.
Although statistically non-significant fruits harvested with stalk resulted into lower PWL as compared
to those without stalk. A similar result was noted by Singh et al (1993). The reason behind the higher
loss associated with the fruits harvested without stalk and stored under ambient condition might be due
to more decay loss as exposed surface of stalk or scar left at the time of harvesting creates avenue for
the entry of pathogen. Pathak and Shrivastava (1969) have supplied similar explanation. They have also
noticed higher decay loss and poor shelf life in mango fruits harvested without stalk.
pH of fruit juice
pH of the fruit juice with respect to harvesting method and calcium treatment is presented in Table 2.
pH of fruit juice harvested without retaining the stalk showed slightly higher pH (4.053) compared to
those harvested with stalk (4.018). There was no apparent effect of calcium treatment albeit it was
recorded maximum (4.067) in control fruit and that of minimum (4.017) to 0.75% calcium treated fruit.
Njoroge and Kerbel (1993) have also reported the significant effect of calcium on pH of fruit juice and it
was higher (4.49) in control than that of 0.75% calcium treated fruits (4.47). Since calcium chloride is
acidic in nature it might have lowered the pH of the treated fruits.
Table 2. Biochemical parameters and shelf life of tomato as affected by harvesting methods and calcium
chloride
Treatment
pH
TSS (0brix)
Titrable acidity, %
Shelf life
Harvesting method
Without stalk
4.05
3.22
0.485
12.93
With stalk
4.03
3.15
0.494
15.00
SEM
0.009
0.064
0.018
0.23
Calcium Chloride
Water
4.067
3.21
0.479
11.00
0.25%
4.044
3.33
0.514
12.83
0.50%
4.028
3.12
0.526
13.33
0.75%
4.017
3.13
0.433
16.17
1.00%
4.022
3.13
0.496
16.50
SEM
0.018
0.101
0.029
0.39
Total soluble solids
Harvesting method did not affect the Total Soluble Solids (TSS) content of fruit juice although it was
slightly higher in the fruits harvested without retaining the stalk (3.218%) as compared to that having it
(3.149%). Similarly, it was also not affected by the calcium treatment (Table 2). As the storage period
prolonged the TSS of the fruit increased. During the storage weight loss is mainly due to the water loss
and that lead to higher concentration of sugars in fruits. The experiment conducted by Subedi and
Bhattarai (1995) had also the similar type of results. Agar and Kaska (1995) also reported similar
results. Singh et al (1993) conducted an experiment to study the qualitative changes in storage in mango
due to harvesting methods and found that there was no significant difference in TSS in fruit harvested
with or without stalks after 6 days of storage.
Titrable acidity
There was also non-significant effect of harvesting method and calcium treatment on Titrable acidity
(TA) content of fruit juice. TA of the fruit juice with respect to harvesting method and calcium
treatment is presented in Table 2. TA of fruit juice harvested with stalk showed slightly higher (0.494%)
compared to those harvested without stalk (0.485%).

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During the storage the fruit itself might utilize the acids so that the acid in the fruits during storage
periods decrease. The change in total titrable acids during storage was mainly due to the metabolic
activities of living tissues during which depletion of organic acids takes place. Decrease in total acidity
and increase in total sugars and TSS during storage at room temperature was also observed by Ramana
et al (1979).
Shelf life
The shelf life of tomato fruits was significantly affected by the harvesting method and calcium
treatment. Irrespective of calcium chloride treatment, tomato fruits harvested with stalk had maximum
shelf life (15 days) as compared to those harvested without stalk (12.93 days) (Table 2). The longer
shelf life and better marketability were also observed in tomato fruits harvested with a small stalk by
Singh et al (1993).
Figure 1. Interaction effect of calcium chloride and harvesting methods on shelf life of tomato.
The calcium treatments significantly influenced the shelf life of tomato fruits. As the concentration of
calcium increased, the shelf life of fruits increased. The maximum shelf life (16.50 days) was noticed in
1% calcium chloride treated fruits compared to the control (11 days). These results were in conformity
with that of Wills and Tirmazi (1982). Calcium treatment could extend storage life and reduce incidence
of physiological disorders and storage rots (Sharma et al 1996).
The interaction between calcium treatment and harvesting methods were non-significant. However,
there was a trend of increasing shelf life owing to each increment in the level of calcium in each of
harvesting methods (Figure 1). Fruits, which were harvested with stalk and treated with 1% calcium
chloride, have highest shelf life of about 17.5 days, where as the shelf life was only 9.5 days for control
fruits harvested without stalk.
Tomato is rapidly gaining its importance as essential nutritional vegetable commodity and income
generating crop in Nepal. Treating the tomato fruits with calcium chloride at the rate of 1% could extend
the shelf life and minimize the physiological weight loss. Tomato fruits harvested with stalk could
prolong the shelf life as compared to those harvested without stalk.
ACKNOWLEDGEMENTS
Authors are grateful to SM Shakya, MD Sharma and GD Bhatta for their valuable suggestions and kind help
during the research period. The financial support was provided by Hill Agriculture Research Project (HARP)
under the research project Improvement in post harvest shelf life of fruits and vegetables in hills of Nepal.
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