Total Phenol Content and Chilling Injury of Normally- or Deficit- Irrigated Fresh Green Olives during Storage E.D. Pliakoni and G.D. Nanos Laboratory of Pomology, School of Agricultural Sciences University of Thessaly Fitoko str., 38446 Volos Greece Keywords: Olea europaea, irrigation, phenolics Abstract The effect of deficit irrigation of olive trees on fruit total phenol content and chilling injury during cold storage was examined. ‘Konservolea’ and ‘Chondrolia’ olive trees were irrigated based on the farmer’s decision (control, exceeding 100% evapotranspiration) or deficit irrigated during stone hardening and final flesh swelling (irrigation water around 50% of control). Green olive fruit quality was evaluated at harvest and every week plus 1 day shelf life during 4 or 5 weeks storage at 5°C and included skin color, flesh firmness, % flesh dry matter, total phenol content and chilling injury (CI) symptoms. CI was subjectively evaluated as discoloration of flesh and skin due to injury and not due to ripening. In ‘Konservolea’ olives, skin color darkened after long storage due to internal CI (flesh browning), while there were no significant differences in total phenol content and CI during most of the measurements in fruits from control or deficit irrigated trees. In contrast, total phenol content in deficit irrigated ‘Chondrolia’ olives was higher at harvest and until the development of significant CI than control irrigated fruit, while a similar trend was found in CI early in storage between the two treatments. In the same cultivar, fruit total phenol content decreased with time in cold storage as severe CI symptoms appeared. ‘Konservolea’ green olives had lower total phenol content and sensitivity to low temperature storage compared to ‘Chondrolia’ green olives. These data could relate olive fruit total phenol content to CI sensitivity during cold storage. INTRODUCTION Chilling injury in horticultural crops is manifested as ion leakage and tissue breakdown due to membrane integrity loss and malfunction. These membrane changes occur after prolonged storage of subtropical or tropical origin fruits, but also of a variety of temperate-zone fruits, at temperatures below a safe level but above freezing. Olives, due to their subtropical origin, are susceptible to chilling injury and, in the case of green olives; it is manifested as flesh browning, which progressively appears on the outer part of the fruit as duller color and, with the advancement of damage, as brown patches on the fruit surface (Kader et al., 1990). Although green olive fruit storage is of limited importance, two important Greek table olive cultivars have been found to have different sensitivity to chilling injury. ‘Chondrolia’ olives are very sensitive to cold storage showing severe chilling injury symptoms even after 1-2 weeks storage at 5°C. On the contrary, ‘Konservolea’ olives are much less sensitive to chilling injury withstanding storage at 5°C without any symptoms for more than 3 weeks (Nanos et al., 2002). Thus, they could be an interesting system to study chilling injury. Water scarcity is an important problem around the Mediterranean region, thus ways to reduce its use in agriculture are desperately needed. With the recent expansion of intense olive cultivation in the Mediterranean and around the world, scientists focus on efficient olive tree irrigation (Fereres and Soriano, 2007). The effects of deficit irrigation on olive fruit quality have not been considered previously. In our study, we tried to follow any changes in fruit quality and storage ability due 209 Proc. 6 th International Postharvest Symposium Eds.: M. Erkan and U. Aksoy Acta Hort. 877, ISHS 2010