Only slight
yellowing of the plant top leaves was observed in the
plants exposed to 80 ppb of ozone for 8 hours. There were
no significant differences observed in plant response to
this ozone treatment in the phenotypic appearance as well
as in plant growth (Table 1). These results indicated that
naturally occurring single short-term peaks of elevated
ozone concentration would have no any significant
impact on viroid and host interaction at least in the model
pathosystem exploited for this study.