Agriculture Reference
In-Depth Information
treatment with ethylene. Similar results have been reported for mango,
papaya, guava and several other tropical and subtropical fruits. Irradiation
treatment can also be used to control several postharvest diseases of fruit
crops (Table 16.4). But ionizing radiation at doses above1 kGy can induce
various types of physiological disorders in fruits like internal browning in
avocados; skin discoloration and stem darkening in grapes; skin damage
in bananas; internal cavities in lemon and lime, etc.
TABLE 16.4
Doses of Irradiation for Different Fruits for Postharvest Disease Control
Fruit crop
Minimum dose required
(Gy)
Maximum dose tolerated
(Gy)
Apple
150
100-150
Apricot, peach, nectarine
200
50-100
Avocado
—
15
Lemon
150-200
25
Orange
200
200
Strawberry
200
200
Grapes
—
25-50
For the control of postharvest diseases generally, a minimum dose of
1.75 kGy is required for effective inhibition of postharvest fungi. So to
avoid such a high dose, combination treatment such as heat + irradiation
is sometime used. Such combination has been shown to be effective for
control of brown rot on stone fruits and anthracnose on mango and pa-
paya. Irradiation at doses below1 kGy is an effective insect disinfestations
treatment against various species of fruit flies, mango seed weevil, navel
orange worm, codling moth, scale insects and other insect species of quar-
antine significance in marketing fresh fruits. Most insects are sterilized at
doses of 0.05-0.75 kGy; some adult moths survive 1 kGy, but their prog-
eny are sterile. For mango irradiation at a dose between 0.25-0.75 kGy is
used for quarantine treatment and shelf-life extension.
