الفهرس 
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Abstract
Two Field experiments were carried out in the Desert Research Centre (D.R.C.) Experimental Station at Mariout region, North Western Coast of Egypt, during 1996/97,
1997/98, 1998/99 winter seasons each, to study the effect of supplementary irrigation treatments and some growth regulators application on growth, water status, chemical composition, yield and its attributes of wheat.
The study included two examined wheat cultivars Sakha-8 & Gemeza-3, in addition to, 16 treatments were the combination of foar supplemental irrigation treatments i.e. (either rainfed, sowing, heading or filling irrigation) and four growth regulators treatments i.e. (control, IAA, GA3, or CK.s).
Results obtained could be summarized as follows:
I. Under inadequate rainfed conditions, sowing irrigation application was the most important treatment for increasing plant emergency followed by improving all growth characters, water status, chemical composition, yield and its attributes.
2. Under enough rainfed water supply, the heading stage irrigation seemed to be the efficient treatment for progressing most of the studied characters i.e. growth characters, water status, chemical composition, yield and its attributes.
3. Growth regulator application led to increase wheat production as a result of encouraging all plant growth characters, water status, chemical composition, yield and its attributes. GA3 application was more effective than IAA and CKs in increasing wheat yield of both two examined varieties under different conditions of drought stress levels. This because it encouraged the accumulation of the
endogenous IAA, GA3 and CKs associated with l,
enhancing juvenility and relaying senescence
metabolism due to decreasing the endogenous levels of ABA and Proline.
4. In the interaction level; under severe drought conditions of 96/1997 sowing irrigation x GA3 was so recommended for increasing the wheat yield and its
attributes. While in 97/1998 results indicated that highest observations of yield and its attributes were drived from heading irrigation x GA3 , on the other hand heading x CKs was recommended for the same target under 9811999 conditions.
5. The models observed in this study were : Biological yield = grain yield x 300 % (Sakha-8)
Biological yield= grain yield x 350 % (Gemeza-3)