Characterization of biochemical factors affecting crop load in three olive cultivars

The dynamics of crop load due to alternate bearing in olive are poorly known, as many environmental conditions and endogenous factors can have a key role in this physiological phenomenon. The aim of this study was to explore the alternate bearing in three olive cultivars by following and determining some biochemical factors likely involved in this physiological phenomenon. This study was carried out in an olive orchard (Olea europaea L., cultivars Chemlali, Koroneiki and Arbosana) located in Sfax, Tunisia, during two consecutive years (2014–2015). Crop load alternation provoked good fruit and oil productions in the ON year (2014), followed by low crops (meanly -57% for fruits and -61% for oil) in the OFF year (2015). For all the three cultivars, leaves and fruits of olive plants in the OFF year generally showed reduced pigments, decreased enzymatic and non-enzymatic antioxidant defences, and their abscisic acid (ABA) homeostasis was disrupted. All the studied factors can interact in determining the alternation of high and low crop load in olive tree and its effects on fruit/ oil yield and plant physiological status.