RESPIRATION OF CHERRIES DURING RIPENING
Sweet cherries (Prunus avium), unlike other stone fruits, are considered non-climacteric (Seymour et al., 1993). Though some authors report a climacteric-like respiration pattern, most do not (Hartmann, 1989; Li et al., 1994; Andrews et al., 1995). We tested whether cherries might show a climacteric peak well before harvest, considering that cherry colour turns early in development. Fruits of cvs. ‘Cerasera’ and ‘Perazzo’ were picked weekly, beginning 30 d before commercial harvest, when fruits were turning from green to whitish and were only 33% of their final weight, until fully ripe. Within 4 h after picking, cherries were weighed into jars (250 g/jar, 2 jars/cv.) with their pedicels in water to avoid desiccation. Jars were held at 20°C and flushed with CO2-free air at 20 l/h. CO2 concentration was measured at exit by IRGA, starting 24 h after picking and continuing daily for 7–10 d, until fruits began to decay. If only the 24 h respiration value for each picking is considered, there was a respiration peak at the second picking for both cultivars (Figure 1). Time-course behaviour is more revealing. First-pick cherries showed an early peak in respiration rate similar to a climacteric peak, followed by a decrease, then an increase due to rotting. Subsequent pickings did not show the initial respiration peak, but only a decrease followed by a late increase. Such early climacteric-like respiration behaviour was recorded by Blanpied (1972) and Hartmann (1989), but was not interpreted as a climacteric rise; while other authors, studying respiration in the “ripening” period, i.e. after colour turning, did not find a peak. However Blanpied (1972) suggested the possibility that cherries had responded to ethylene during growth phase 1 and 2, and Hartmann (1989) reported that ethylene production increased greatly at the end of ageing of green fruits harvested 5–6 weeks after anthesis, when cherries exhibited a respiratory rise. In the same growth period other important changes have been observed, e.g, in different pectin fractions (Fils-Lycaon et al., 1990). If the hypothesis is made that cherry is a climacteric fruit, whose climacteric rise happens very early at the mature green stage, and that ripening cherries should be considered as post-climacteric, then all abnormalities observed in respect to a non-climacteric behaviour are accounted for: thus lack of a respiration increase in response to ethylene treatments, as well as the presence of cell wall hydrolases, can be easily expected in post-climacteric cherries, as they are in tomato or in other recognised climacteric fruits.
Eccher, T. and Noè, N. (1998). RESPIRATION OF CHERRIES DURING RIPENING. Acta Hortic. 464, 501-501