Respiration of Oranges and Grapefruits Harvested at Different Stages of Development

Abstract

A bstract. Young and unripe oranges and grapefruits stored at 15° or 20' evidenced shortly after harvest a marked increase in respiratory rate, and then a well-defined maximum which was followed by a decrease. Ethylene production by oranges (measured by the manometric method) was observed, with curves parallel to the respiratory curves. The respiratory upsurge was accompanied by color changes typical of maturity in the above fruits, and by abscission of stem-ends. When fruit was harvested close to or at commercial maturity, it evidenced a gradual respiration decrease without any upsurge. No ethylene production was detected in oranges of this stage. Controversial opinions exist among research workers concernin-g the post-harvest respiration of oranges. It has been observed that during storage in air, there is a graduall decrease in the respiration rate of ripe oranges (6,7). On the basis of these observations Biale classifies oranges as non-climac-teric fruits (3, 4). The above assumption has been strengthened by results obta,ined by Bain (1), who observed a gradual decrease in the respiration rate (expressed in unit fr wt) of Valencia oranges harvested at different stages of development, from early fruit set through the stages of cell divisions, enlargement and maturation. On the other hand, Trout, et al. (8, 9) reported an increase in the respiration rate of Wash,ington navel and Valencia oranges immediately after harvest, especially if picked a little before commer-ci,a,l maturity. During work carried out on physiological