Respiration rate was high in young fruit with a rapid decline to 10 DAF followed
by only a slight decrease towards 80 DAF (Fig. 2). Ethylene production was high
in young fruit followed by almost no production up to 70 DAF. Mature fruit
produced much ethylene but showed no increase in respiration and the repeated
experiments conducted in different seasons had the same tendency (data not shown).
Passion fruit has been classified among climacteric fruits which have distinguishing
features of increased respiration and ethylene production rates during ripening
and a response to exogenously applied ethylene (Biale and Young, 1981). In this
study, however, purple passion fruit showed no respiratory climacteric on the vine
in spite of a substantial amount of ethylene production. Generally, distinctions
between climacteric and non-climacteric fruits have been examined in harvested
fruit. Indeed, detached fruit at and after 40 DAF showed marked respiratory
climacteric patterns (Fig. 3) with large amounts of ethylene production (Fig. 4).
Younger fruit, that is before 40 DAF, did not show increases in respiration and
ethylene production rates after harvest (data not shown). Ethylene production by
detached fruit began earlier as the fruit aged progressively on the tree (Fig. 4),
although fruit younger than 40 DAF did not show any significant levels of ethylene
production. Similar results with more immediate commencement of ethylene in the
later harvested fruit have been reported in avocado (Eaks, 1980) and Japanese
apricot (Inaba and Nakamura, 1981) fruits. Ethylene production by the detached
fruit was lo- to 20-fold greater than that by on-the-vine fruit and much higher than
the quantity reported previously (Akamine et al., 1957; Sjaifullah and Lizada, 1985