الفهرس 
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Abstract
This investigation aimed to study sensitivity of some olive cultivars to drought.
Uniform and healthy one-year-old mist propagated
transplants were selected and planted individually in
plastic pots of 25 cm diameter, filled with (6 Kg) constant weight of loamy sand soil on the tai half of February in both seasons.
All pots were irrigated at constant rate (510 cm/pot) to reach 100% available water of soil at two days interval till mid March (strating the experimental work). Also, they were fertilized by Kristalon (2 gm/litre) twice monthly.
This experiment was conducted during two successive seasons to study the effect of three irrigation levels on the above mentioned five olive seedlings cvs. and was set in a completely randomized design. This experiment involved 15 treatments each replicated 3 times and each replicate represented by three olive seedlings. The three irrigation levels were irrigation after depletion of 25, 50 and 100% of available soil water (A.W.).
The experiment was terminated at the end of October for the two seasons.
The vegetative growth such as increasing rate of stem length and diameter, average number of shoots, average shoots length, average number of leaves, average leaf area, total leaf area, fresh and dry weight of various plant organ (leaves, stem, shoots and roots) were measured. Also, physiological and chemical characteristics such as leaf osmotic pressure, photosynthetic pigments (Chl. A, B and carotenoids) as well as proline content and leaf minerals content (N, P and K) were determined.
The results of this investigation can be summarized as follows:
Concerning the effect of irrigation levels on vegetative growth, it is clear that the all studied characters were significantly decreased by increasing the water stress in both seasons. The most reduction occured when the seedlings were irrigated after 100% depletion of available soil water. On the other hand, the irrigation after 25% depletion of available soil water gave the highest values in concern with the studied vegetative growth characters in the two experimental seasons.
Regarding the effect of irrigation treatments on the physiological and chemical characters, it is obvious that the osmotic pressure was significantly increased by decreased the available soil water, this increase reached to the maximum when the seedlings were irrigated after 100% depletion of available soil water. But it was decreased by increasing the available soil water (treatment which was
irrigated after 25% depletion of available soil water) in the two seasons.
Concerning the effect of irrigation treatments on photosynthetic pigments and leaf P and K content, it is clear from the obtained results that the irrigation after 25% depletion of available water increased them while, they were decreased by increasing the drought (irrigation after 100% depletion of A.W.). The other chemical characters such as leaf proline and nitrogen content exhibited an opposite trend in both seasons.
Regarding the specific effect of studied cultivars on vegetative growth characters, Agisi Aksi showed generally the highest values of vegetative growth followed in descending order by Frantoio, Mostazal, Manzanillo and Verdal in both experimental seasons.
Concerning the effect of cultiv.