Post harvest diseases fruits and vegetables - Xavier University ...

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
Means for Maintaining Host Resistance 137
The reduction in fungal growth under hypobaric pressure can be
attributed to the reduction in the partial O2 tension, which decreases
gradually with the decrease in the total pressure to 100 or 50 mm Hg.
However, growth retardation may be due, at least in part, to other
factors, such as reduction in the CO2 partial pressure or the accelerated
escape of volatile compounds from the tissues (Apelbaum and
Barkai-Golan, 1977).
Beneficial effects of hypobaric storage have been reported for various
fruits. Storing apples under LP conditions resulted in delayed softening,
control of physiological disorders and reduced decay development, which
resulted in extended shelf life after removal from storage (Dilley et al.,
1982; Laugheed et al., 1978). Several Florida cultivars of mango which
ripened in air at shelf-life temperature, showed less anthracnose
(Colletotrichum gloeosporioides) and stem-end rot (Diplodia natalensis)
when they had previously been stored under LP at 13°C. The reduction
in decay coincided with a retardation in fruit ripening, permitting a
prolonged storage at 13°C (Spalding and Reeder, 1977). Similarly,
exposure of papayas to LP at 10°C during shipment, inhibited both
ripening and disease development as compared with fruit stored in
refrigerated containers at normal atmospheric pressure (Alvarez, 1980).
Studies on LP storage of avocados suggested that atmospheres both low
in O2 and high in CO2 are required for successful suppression of
anthracnose development and for increasing the percentage of acceptable
fruit retained after softening in air under normal pressure (Spalding and
Reeder, 1976). Studies with various Yruit-vegetables', such as tomatoes,
peppers and cucumbers, found a high incidence of decay after storage at
subatmospheric pressure; in order to suppress decay, the combination of
LP with postharvest fungicidal treatments was required (Bangerth, 1974).
C. GROWTH REGULATORS
Plant growth regulators, or plant hormones, may - similarly to low
temperatures - suppress decay development indirectly, by retarding
ripening and senescence processes in fruits and vegetables, and
maintaining the natural resistance of young tissue.
Prolonged storage of citrus fruits generally results in the development
of stem-end fungi, mainly Diplodia natalensis, Phomopsis citri,
Alternaria citri and Fusarium spp. Applying the synthetic auxin
2,4-dichlorophenoxy acetic acid (2,4-D) to citrus fruits prior to storage
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