Quantitative Seasonal Changes in the Leaf Phenolic Content Related to the Alternate-Bearing Patterns of Olive (Olea europaea L. cv. Gemlik)

-

Using HPLC, the seasonal changes in the phenolic compound content of the leaves ofthe Gemlik olive cultivar (Olea europaea L) has been investigated with respect to theeffects on the alternate bearing of the cultivar. For this purpose, the leaf concentrations ofoleuropein, chlorogenic acid, caffeic acid, 3-hydroxycinnamic acid, scopolin and pcoumaricacid were analyzed at 10 day intervals around the years. The quantity anddistribution of these phenolics in the leaves showed significant differences in 2008 (offyear) and 2009 (on year). In the “on” year, the levels of chlorogenic and p-coumaric acidswere high, whereas the abundance of other phenolic compounds was low. In contrast,during the “off” year, the chlorogenic and p-coumaric acid levels were at low levels,whereas the levels of the other phenolics were high. We found a negative relationshipbetween the chlorogenic acid and caffeic acid concentrations in the “on” and “off” years:the amount of caffeic acid in the leaves was high, and the chlorogenic acid level was low.The contents of chlorogenic acid, caffeic acid, 3-hydroxycinnamic acid and p-coumaricacid were significantly different in the “on” and “off” years. These findings indicated thatthese compounds and the other phenolics examined in this study were related to alternatebearing. Interestingly, the levels of all of the phenolic compounds examined in this studywere at their highest during the dormant season.