Evaluation of the effects from foliar application of four biostimulants (two inorganic and two organic), on olive fruit weight, infestation levels by the olive fruit fly and in olive oil quality in a high density linear olive system and two olive varieties adapted from mechanical harvesting

Abstract

The study has compared the impacts of planting density regimes and biostimulant use on the olive fruit characters on pest pressure and the quality of oil in an olive orchard in the Mediterranean region in northern Greece. Three planting densities, which were super high density high density and middle density and two commonly grown olive varieties were used to conduct the experiment in a commercial olive grove. The comparison was made between four biostimulants such as organic and inorganic products with a control that was not treated with repeated applications on the foliage during the growing season. Oil yield in the field measurements and laboratory analyses of fruit weight olive fruit fly infestation were determined by acidity and peroxide values. Findings showed that the planting density had significant effects on the fruit development whereby the dense systems tended to have greater productivity per hectare, although individual fruit sizes varied with variety. Biostimulant treatments were cultivar specific as some products increased the weight of fruits and oil yield whereas others increased the quality criteria of the oil. The oil acidity and the peroxide value was within the extra virgin olive oil standards in all the treatments despite the detectable differences between the biostimulants used that evidenced differences in the oxidative stability. Extra assessment of the incorporation of olive leaves in malaxation showed few effects on acidity and cultivar selective reactions in oxidative behavior. The general results of the studies are that the use of the right planting density and biostimulant application to promote the quality of yield fruits and oil stability is essential. The combination strategy provides practical information towards enhancing sustainability productivity and quality in the contemporary olive production systems in the Mediterranean