Influence of different irrigation strategies in a traditional Cornicabra cv. olive orchard on virgin olive oil composition and quality

The olive tree is generally grown under rain-fed conditions. However, since the yield response to irrigation, even with low amounts of water, is great there is increasing interest in irrigated agriculture. The main goal of this study was therefore to optimize sustainable irrigation conditions in the Cornicabra olive cultivar grown in Castilla-La Mancha, a region where the aquifers are over-exploited, and to study the effect of different irrigation strategies on the composition and quality of Cornicabra virgin olive oil. Different irrigation treatments, based on regulated deficit irrigation (RDI), 100% ET_c, 125% ET_c, and rain-fed as control, were applied to a traditional olive orchard (cv Cornicabra) in a randomized complete-block design with four replications. The average olive production of the trees grown under rain-fed conditions was much lower, about 35%, than that obtained by applying the different irrigation treatments studied, between which practically no difference were observed. The total phenol content, which affected the sensory bitterness in the oils, decreased significantly as the amount of supplied water increased. This is very relevant, as high levels of phenols, typical of Cornicabra virgin olive oils, may decrease consumer preference. Notably, one of the RDI strategies produced olive oil similar in composition and quality to that obtained by 100% ET_c but with reduced water usage.