Summer deficit-irrigation strategies in a hedgerow olive orchard cv. 'Arbequina': effect on fruit characteristics and yield

Maximum production in hedgerow olive orchards is likely not achieved with maximum evapotranspiration over the long term. Thus, regulated deficit irrigation (RDI) should be considered as a management option. Four irrigation treatments were evaluated during the summer, when olive is most drought resistant. Control (CON) was irrigated to maintain the root zone close to field capacity. Severe water deficit was applied by irrigating 30% CON from the end of fruit drop to end July (DI-J) and from end July until beginning of oil synthesis (DI-A). Less severe water deficit was applied during July and August (DI-JA) by irrigating 50% CON. Flowering, fruiting, abscission, fruit development, fresh and dry weight of fruits, and oil production were evaluated. There were not significant differences in number of buds initiated, number of fruits per inflorescence and fruit drop. Oil production was significantly different between irrigation treatments in all experimental years. CON produced more oil and fruit with higher oil % than DI-A and DI-JA. Oil production of DI-J was not significantly reduced compared with CON and oil% was greater. DI-J was the most effective RDI strategy; with 16% less applied water relative to CON. Average loss in oil production of 8% was not significantly different to CON. While DI-JA saved most water (27%), oil production was reduced by 15%. Greatest loss in oil production (21%) was observed in DI-A with water saving of 22%.