engleski

Gas exchange properties of olive cultivars at the time prior to flowering, during the full bloom and early fruit growth

Olive tree develops large number of flowers but only a small proportion matures into fruits. Petals, anthers and style, which comprise the larger portion of the flower, drop after anthesis and rapid fruit growth takes place. During flowering, reproductive process becomes the plant’s dominant sink for carbohydrates at the expense of vegetative growth and it may affect leaf photosynthesis. The aim of this study was to observe the gas exchange parameters on mature leaves from one year old shots in the inflorescences zone and young, fully expanded leaves in cultivars ‘Leccino’, ‘Levantinka’ and ‘Oblica’. Three measurements were performed, at stage before flower opening, at full bloom and during the rapid fruit growth. The photosynthetic rate (A), stomatal conductance (gsw), transpiration (E), and leaf vapor pressure deficit (VpdL) were significantly influenced by cultivar, leaf age and time of measurement. ‘Levantinka’ and ‘Oblica’ had higher gsw and E compared to ‘Leccino’, however, the A was the highest in ‘Levantinka’ (16.2 μmol m-2s-1), followed by ‘Oblica’ (14.39 μmol m-2s-1) and ‘Leccino’ (11.1 μmol m-2s-1). The highest Hydro N tester (HNT) value was measured in ‘Oblica’ (100.4), and followed by ‘Levantinka’ (68.6), while the lowest was found in ‘Leccino’ (54.4). Higher A, gsw and E were found for leaves in the zone of inflorescences compared to young leaves. At the stage of rapid fruit growth, gsw, Ci and E were higher compared to measurements before the flower opening or at the full bloom, however A and VpdL were higher only when the stage of rapid fruit growth was compared to full bloom stage. In the period of the rapid fruit growth, lower HNT values were observed compared to values found during the full bloom. In our study, higher demands for assimilates during the fruit development corresponds to highest values found for gas exchange parameters.

Olea europaea; photosynthetic rate; stomatal conductance; transpiration; leaf vapor pressure deficit; chlorophyll index

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