Efficiency of Salicylic Acid Application on Postharvest Perishable Crops - Salicylic Acid: Plant Growth and Development - page 338

could delay the increase in reducing sugar content and maintains a lower TSS but
in fruits during storage (Asghari and Aghdam 2010 ). Srivastava and Dwivedi
( 2000 ) found that SA treatment leads to a decrease in invertase activity and that of
reducing sugars and also delayed breakdown of starch in banana fruit during
ripening. Aghdam et al. ( 2009 ) suggested that a lower TSS of kiwifruit treated with
methylsalicylic acid was concomitant with reduced ethylene production and
decreased sucrose-phosphate synthase activity. Moreover, pre-harvest treatment of
SA (10 -6 M) regulated sugar contents (reducing and nonreducing) in both pepper
leaf and fruit (translocation from source to sink) and stimulated invertase activity
(Elwan and El-Hamahmy 2009 ). This indicates that SA treatment can delay the
fruit ripening during storage and also enhance fruit quality by increasing total
sugar content when pre-harvest treatment of SA is applied.
Titratable acidity (TA) is directly related to the organic acids content in fruits.
Normally, TA and total organic acid content decline throughout ripening process.
However, treatment of kiwifruit with SA maintained higher TA than control fruit
during storage (Kazemi et al. 2011a , b ). In the similar vein, both pre- and post-
harvest SA treatments maintained higher TA of winter pineapple fruit than the
control (Lu et al. 2011 ). In fresh-cut product, SA treatment also delayed the loss of
TA in Chinese water chestnut during storage for 4 days (Peng and Jiang 2006 ).
Colour changes during storage such as the loss of greenness, the increase in
yellowness and the development of certain pigments relating to ripening and
senescence processes, are the important factors affecting the quality of horticul-
tural produce during postharvest period. Chlorophyll content is a key factor for
green vegetables and florist green. It is widely recognized that the loss of chlo-
rophyll content results to the loss of greenness affecting visual quality and mar-
ketability. Ethylene is widely accepted as a key factor playing major role in the
loss of chlorophyll during senescence. The regulation of ethylene production or its
action could maintain surface colour of the produce during postharvest period. The
application of SA, an ethylene inhibitor, can delay the loss of greenness of veg-
etables and florist green. Wei et al. ( 2011 ) found that the chlorophyll content in
asparagus was maintained by SA treatment, however, the high concentrations of
SA cause deterioration of the pigment. SA treatment can prolong the shelf-life and
delay chlorophyll degradation of detached leaves of Hippearstrum x chmielii
(Lukaszewska and Kobyli ´ ski 2009 ). In the similar vein, total chlorophyll content
of carnation cut flowers was also delayed by SA treatment (Kazemi et al. 2011a ,
b ). Moreover, SA treatment could also maintain the level of other pigments in the
produce. Huang et al. ( 2008 ) reported that pre-harvest treatment of SA could
enhance lycopene content in tomato fruits during development stages and slowed
down the degradation of lycopene and b—carotene during storage. This indicates
that SA can activate the lycopene biosynthesis pathway, including up-regulation of
the gene encoding the enzymes relating to lycopene level, during fruit develop-
ment. Moreover, Elwan and El-Hamahmy ( 2009 ) suggested that SA applied to the
intact foliage induced the accumulation of carotenoids in pepper fruits. In contrast,
postharvest treatment of SA delayed the accumulation of carotenoids and lycopene
in tomato fruits whilst the accumulation of total chlorophyll was detected (Pila