INFLUENCE OF HARVEST DATE AND STORAGE ON H₂O₂ AND SCAVENGER SYSTEMS IN ‘PASSE CRASSANE’ PEARS

We studied the processes of pear ripening and senescence by analysing the production of H₂O₂, the changes in malondialdehyde (MDA) concentration and the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR). Pear fruits cultivar ‘Passe Crassane’ were picked at immature, commercially ripe and full ripe stages.
Commercially ripe pears were stored for 3 months under normal atmosphere (1,5 °C; 95% R.H.). The results showed that a strong increase in H₂O₂ production occurred at full ripeness and after cold storage.
SOD activity did not change in fruits of different harvest dates, whereas it significantly decreased in fruits stored at low temperature.
APX and GR activities reached high levels during ripening, but after storage APX activity decreased, while GR activity strongly increased.
MDA concentration was not affected by ripening, but after storage it was significantly higher.
These data suggest that, during ripening, the increase in H₂O₂ production is not associated with membrane damage due to lipid peroxidation.
In this period the enhanced APX activity could partly account for an effective removal of the higher peroxide production and the greater GR activity would ensure the reduction of glutathione, which is involved in the reconstitution of ascorbate.
During storage at low temperature, the decrease in SOD and APX activities and the enhanced production of H₂O₂, probably due to a chilling stress, are associated with a strong increase in MDA content, indicating that in this condition a damage of membranes took place.

VIII International Symposium on Pear

A.M. Spinardi, C. Visai, N. Negrini, M. Coccuci

harvest, storage, scavengers, H₂O₂, lipid peroxidation

https://doi.org/10.17660/ActaHortic.2002.596.152