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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
220 Postharvest Diseases of Fruits and Vegetables
0.125-0.5 kJ m-2. These results were obtained both for berries wounded
and inoculated just after the UV treatment, and for berries inoculated
24-48 h after the treatment. Similarly to the effect of UV-C light on citrus
fruit (Rodov et al., 1992), an interaction between the UV-C dose and the
time of inoculation was also found in grapes. A significantly lower level
of disease was found, however, in berries inoculated 24-48 h after
illumination than in those inoculated just after the treatment. To check
the possible influence of UV-C illumination on the wound-healing
processes, berries were wounded before illumination and inoculated at
different times (hours) later. Such berries showed lower infection levels
than those wounded after the UV treatment. These results could be due
to a wound-type response since, during the period between irradiation
and inoculation, the wounded berries were kept at 15°C under high-RH,
conditions reported to be suitable for the induction of wound-healing
processes in several fruits and vegetables (Ben-Yehoshua et al., 1988;
Ippolito et al., 1994). However, a disease reduction recorded in grape
berries illuminated after the inoculation of freshly cut wounds led to the
suggestion that the effect of UV-C light was independent of a
wound-healing reaction and could be attributed to UV-C-induced
resistance alone (Nigro et al., 1998). Induced resistance was exhibited
within 24-48 h of irradiation, and increasing the time until inoculation
resulted in increased disease, probably because of a decline in the
UV-C-induced resistance. These results suggest a temporary effect of
UV-C treatments, as was also found in citrus fruits inoculated with P.
digitatum (Droby et al., 1993a).
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