In addition, it is worth mentioning that the stage of maturation
at harvest may influence the actual effects of both water status
and thermal load on postharvest chlorophyll degradation of peduncle.
This aspect has not been investigated here. Nevertheless, the
high respiration rates observed may indicate a pronounced initially
metabolic activity of peduncle tissues. This may negatively
affect photosynthetic activity and promote the chlorophyll degradation
during aging if fruit have been harvested at a later stage of
development.
However, if temperature history of the cherries is known,
changes in peduncle photosynthetic activity can be directly related
to the pronounced water losses. The present results indicate that
both rapid short-term and slow long-term water losses yielded
nearly the same direct tremendous effects on the photosynthetic
capacity not only on its current activity. This points out that chlorophyll
fluorescence analysis and especially CF imaging provides
a very effective means to non-destructively analyse changes in
peduncle water status and hence, in freshness of the entire cherry
fruit.
Ripeness status and choice of cultivars may influence the
interrelation. Furthermore, preharvest conditions such as climatic
parameters, irrigation, fertilisation etc.may affect tissue resistances
to water vapour transfer (Linke and Kläring, 2004). Nevertheless,
such analyses enables the building of a model that allows the estimation
of the peduncle water content of fresh cherries without the
need to detach the peduncle from the fruit body. The application of
a knowledge-based model of the relationship between these two
parameters may facilitate the investigation of many postharvest
scenarios and of the effects of climatic impacts on produce quality.
Accordingly, monitoring changes in peduncle freshness is very
helpful to evaluate the success of various postharvest treatments
on improving cherry fruit shelf-life.
In conclusion results obtained from the analyses of fruit peduncle
water content and hence, fruit freshness, may provide an
effective means to evaluate the efficacy of technical processes
introduced or optimized to improve quality maintenance of sweet
cherries. CFI provides information on the physiological activity
of the peduncle tissue which is closely related to their water
status, which in turn tightly reflects that of the cherry fruit
body. The knowledge of the effects of thermal loads (degree
and duration) and water losses on changes in fruit peduncle
properties is essential for the unequivocal assessment of secondary
process parameters (e.g. gas concentrations, chemical
treatments).