engleski

Gas-exchange properties of olive cultivars prior to flowering and during full bloom and early fruit growth

Olive trees develop large numbers of flowers, but only a small proportion mature into fruits. The petals, anthers and style, which comprise the larger portion of the flower, drop after anthesis, and rapid fruit growth takes place. During flowering, the reproductive process becomes the plant's dominant sink for carbohydrates, at the expense of vegetative growth, which may affect leaf photosynthesis. The aim of this study was to observe the gas- exchange parameters on mature leaves from 1- year-old shoots in the inflorescence zone and young, fully expanded leaves in cultivars 'Leccino', 'Levantinka' and 'Oblica'. Three measurements were performed, before flower opening, at full bloom and during 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 with 'Leccino' ; however, A was highest in 'Levantinka' (16.2 μmol m‑2 s‑1), followed by 'Oblica' (14.39 μmol m‑2 s‑1) and 'Leccino' (11.1 μmol m‑2 s‑1). The highest Hydro N tester (HNT) value was measured in 'Oblica' (100.4), 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 inflorescence zone compared with young leaves. At the stage of rapid fruit growth, gsw, Ci and E were higher compared with measurements before flower opening or at full bloom ; however, A and VpdL were higher only when the stage of rapid fruit growth was compared with full-bloom stage. In the period of rapid fruit growth, lower HNT values were observed compared with values found during full bloom. In our study, higher demands for assimilates during fruit development corresponded to the highest values found for gas-exchange parameters.

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

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