Relationship between tree water status and physiology, yield, and fruit quality in the table olive (Olea europaea sativa L.) cultivar ‘Nocellara del Belice’

Although the olive (Olea europaea sativa l.) is considered a xerophytic species, long periods of water stress and high temperatures during summer months can greatly affect plant physiology and productivity. In recent years, the use of plant-based water status indicators have become popular in the study of plant-water relationships and in the design of irrigation programs, particularly midday stem water potential (ψstem). The current trend in the irrigation of olive trees is in the development of Deficit Irrigation (DI) systems whereby the water is applied at a rate which is lower than evapotranspiration needs, resulting in only very small reductions in yield. Rather than working towards minimizing crop water deficits, an irrigation manager must decide on what level of deficit to allow and must recognize when that level has been reached. Traditionally, olive trees in Sicily are not watered, with the exception of those destined for the table olive industry. Considering the growth of the table olive industry in Sicily, the choice of a correct irrigation management related to the olive tree stress threshold is necessary in order to save water. In the Belice Valley, where the table olive cultivar Nocellara del Belice is cultivated, irrigation is still managed traditionally, with a high level of variability and water waste. This trial, conducted in two consecutive olive crop seasons (2010 and 2011) aimed to evaluate the effects of deficit irrigation management on tree physiology, yield and fruit quality of the table olive cultivar Nocellara del Belice.