Effect of three water treatments on water status and biomass of olive tree (Olea europaea L cv Meski)

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1 Olive tree Institute, Unit of Sousse, BP n°14. Ibn Khaldoun- 4061 Sousse, Tunisia



Abstract - The objective was to evaluate the effect of three water treatments on biomass by monitoring water status as an indicator of stress. The study consists of applying three water treatments (100, 50 and 25% field capacity (FC)) on one-year-old olive plants (Olea europaea L. cv Meski) during 42 days in a greenhouse under semi-controlled conditions. The evaluation of olive tree response was carried out by monitoring water and osmotic potentials, osmotic adjustment, relative water content and accumulation of dry matter.The water potential decreased by 16 and 28% compared to control plants (T100%) at the end of the experiment, respectively for T50% and T25% plants. The osmotic potential decreased by 50 and 64% compared to control plants respectively for T50% and T25% plants to reach -4.54 and -4.98 MPa due to regression of water stock. As a result, the osmotic adjustment increased to 1.51 and 1.95 MPa respectively for T50% and T25% plants at the end of the experiment. Olive tree decreases its water and osmotic potentials and the osmotic adjustment would be more important according to the progression of the degree of stress. T50% and T25% plants had a passive osmotic adjustment of 79 and 89% respectively. Control plants accumulated more dry matter in the roots and stem, while the root/ shoot ratio seemed indifferent to water stress. The water restriction has affected root and stem dry matter in favor of leaves, the first operator of photosynthetic activity.These results indicate that a water restriction for Meski cultivar implies a specific adaptation characterized by a reduction in osmotic potential involving an increase in osmotic adjustment and a shift in the distribution of dry matter maintaining the leaves dry matter of stressed plants similar to those of control plants at the expense of roots and stem to ensure photosynthetic activity.

Keywords: Olea europaea L., Water stress, Leaf water potential, Leaf osmotic potential, Relative water content, Root/shoot ratio.


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