Vegetative, productive and oil quality responses of 'Arbequina' and 'Picual' olive trees to foliar P and K application

A completed hedgerow of cv. Arbequina and a youth vase trained orchard of cv. Picual were fertilized with foliar applications of Phosphorus (P) or Potassium (K) throughout four seasons. The orchards were located near Valdepefias in the dry area of La Mancha (Spain). Vegetative growth, yield and oil quality were evaluated. Foliar treatments did not increase P or K leaf concentration. Most of the evaluated parameters were not significantly affected by treatments. It was observed that the P treatment increased olive growth and oil yield in both orchards and in certain seasons due to an increment in fruit number. P and K application significantly increased 'Arbequina' olive and oil yield in 2008 when spring was wetter than the other years. Oil quality was not modified by fertilizer treatments in the 'Arbequina' orchard. However, oxidative stability was negatively affected by P and K treatments in 'Picual'. Oil extraction could be negatively affected by treatments because of the increase in the water content in the fruit obtained from both orchards.