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Bruising susceptibility of Manzanilla de Sevilla table olive cultivar under Regulated Deficit Irrigation

Casanova, L., Corell, M., Suárez, M.P., Rallo, P., Martín-Palomo, M.J., Jiménez, M.R.
Agricultural water management 2017 v.189 pp. 1-4
Olea europaea, deficit irrigation, developmental stages, drought, groves, irrigation rates, manual harvesting, mesocarp, olives, rehydration, trees, water stress
The olive tree (Olea europaea L.) is a Mediterranean tree adapted to drought conditions and traditionally rainfed. For irrigated olive groves, there is extensive knowledge about the effects of Regulated Deficit Irrigation (RDI) scheduling on the sensibility of different phenological stages and about the importance of rehydration in the last part of the fruit growth stage. Water stress in this period could reduce the fruit size, but the exact extent of this reduction is still unknown. Additionally, table olive varieties may be damaged during harvesting or processing. This results in bruising, superficial browning injuries that progress through the mesocarp. Bruising susceptibility is an important quality parameter in table olives, however it has been little studied in RDI research. Hand-harvested fruits of ‘Manzanilla de Sevilla’ for green processing, treated with two types of RDI and full irrigation, were bruise-induced with a standardized drop to evaluate bruising susceptibility. Bruising index (BI) and external (BAE) and internal (BAI) bruising damage were measured 3 and 24h after the bruising treatment. A full irrigation treatment was set up in order to maintain the Ψh values higher than −1.2MPa before pit hardening and −1.4MPa until harvest. RDI-1 and RDI-2 were irrigated with a full irrigation treatment until 2 and 4 weeks before harvest, respectively. Then, water was withheld until −2.5MPa. RDI-2 can save 50% of the water applied without affecting the fruit weight, volume or pulp-to-pit ratio (fresh and dry). Fruits under RDI treatments are less susceptible to bruising than fruits with a full irrigation treatment, as evidenced by the lower bruising index and the smaller external and internal damaged area. As for the bruising time line, 3h after the bruise inducement, the bruising index and external damaged area had already developed, whereas internal bruising damage continued increasing up to 24h after the bruising treatment.