Oil content and composition in relation to leaf photosynthesis, leaf sugars and fruit sugars in maturing Koroneiki olives – The mannitol effect on oil
Keywords:Fatty acids, leaf photosynthesis, Olea europea, oil content, sugars, total antioxidants.
In Koroneiki olive tree, leaf photosynthesis, and sucrose, glucose, fructose and mannitol concentrations in leaves and fruit were investigated at fruit maturity index (MI) 1.1, 3.8 and 6.9, along with oil accumulation and composition, total phenolics (TP) and total antioxidant capacity (TAC) in fruit during a fully productive season in experiment 1 (I). The effect of mannitol treatment at 50 and 100 mg L-1, applied in mid-October, on oil content and composition, TP and TAC were investigated in fruit harvested 25 d after treatment, at an average MI of 3.4, in experiment 2 (II). In I, in leaves net photosynthesis, and sucrose, glucose and fructose concentrations decreased, but mannitol increased by advancing MI. In fruit, however, concentration of all sugars decreased apart from fructose, which increased. Oil content (% DW), already high initially at MI 1.1, increased slowly thereafter, exhibiting decreases in oleic acid (OL) and increases in linoleic (LL). TP and TAC decreased at MI 3.8, remaining stable afterwards. In II, increasing mannitol concentration promoted oil accumulation and OL in oil and reduced LL slightly, indicating an acceleration of olive metabolism. Practically, mannitol could be applied to hasten the harvest of olives, so as to avoid adverse winter conditions.
The online version of this article (doi: 10.5073/JABFQ.2016.089.001) contains a supplementary file, which is available within the ARTICLE TOOLS on the right.
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