Table olive quality was analyzed in adult ‘Manzanilla de Sevilla’ olive trees subjected to different N–P–K fertigation treatments through five years (1999–2003). A randomized block design with four fertigation treatments was established: irrigated without fertilizer (control), and T200, T400, and T600 treatments, in which each tree was respectively fertigated with 200, 400, and 600 g N per irrigation season of a complex 4N–1P–3K fertilizer applied daily. Fruit yield and fruit physical characteristics and chemical composition were studied in 2002 and 2003. Fruit analysis realized in 2002 showed that the fruit pulp/stone ratio and water content increased with the amount of applied fertilizer. In 2003, a similar trend was found for fruit yield, weight, pulp/stone ratio, volume, longitudinal and transversal diameters, and fruit water and potassium concentrations. On the contrary, the concentration of reducing sugars; Ca, Na, and B; and the fruit texture decreased linearly with the fertilizer dose in 2003. No differences between treatments in fruit and stone shape, or stone volume or polyphenols concentration were found. On the other hand, the effect of the treatments on fruit browning damage was studied in 2003, as well as the fruit quality after “Spanish-style” green processing. In spite of the differences in fruit composition and texture, the fertigation treatments did not affect browning damage. After Spanish-style processing, differences between treatments in fruit weight and texture were again observed, but color, brown spots, and blistering incidence were not modified.
We report the results of a study carried out in a ‘Manzanilla de Sevilla’ olive orchard near Seville, Spain, where the influence of different fertigation treatments on oil chemical composition was considered. Four treatments were established: control (no fertilizer) and T200, T400, and T600 in which each tree, respectively, received 200, 400, or 600 g N per irrigation season of a 4N–1P–3K complex fertilizer applied daily from 1999 to 2003. Results shown here correspond to the last 2 years of the experiment, 2002 and 2003. Fruits were sampled at the beginning of ripeness at the “green” stage. Fruit water content increased with the amount of fertilizer, probably because of the increase of potassium in the pulp. Oil content was unaffected by the treatments, but oil yield increased with the fertilizer dose in 2003 as a result of the number of fruits per tree. Polyphenol content, which is related to antioxidant oil capacity, K225 (bitterness), and oxidative stability were lower in the oils made from trees receiving greater fertilizer doses. The monounsaturated fatty acid content, in particular oleic acid, decreased with increasing amounts of applied fertilizers, whereas polyunsaturated fatty acids, in particular linoleic acid, increased with it.