الفهرس 
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Abstract
Field experiment was conducted in the Farm of Faculty of Agric., Mansoura Univ., Egypt, during 2007 and 2008 seasons to evaluate the role of P and Zn fertilization in overcoming water stress on productivity of sunflower crop in alluvial soils. Also, some soil properties were studied.
Irrigation intervals were applied at two durations i.e. 15 or 21 days after the second irrigation, thus, plant received 8 or 6 irrigations (including planting irrigation), in each season.
Super phosphate (15% P2O5) and PSB using Basillus spp. (inoculation to the soil) were added with planting in 6 levels (0kg P2O5 fed-1, 0kg P2O5 fed-1 + PSB, 7.5 kg P2O5 fed-1, 7.5 kg P2O5 fed-1 + PSB, 15 kg P2O5 fed-1 and 15 kg P2O5 fed-1+ PSB).
Two levels of chelated zinc (0 and 25gm EDTA-Zn fed-1) were applied as foliar spray application in two doses. The first was added in 200 L water per fed at formation of 8 true leaves and the second was added in 300 L water per fed after two weeks from the first dose.
Regression analysis:
Multiple linear regressions illustrated that SMB-N and SMB-P had a high significant role in predicting the seed yield. Also SMB-P, head diameter (H.D.) and head weight (H.W.) had a high significant role in predicting the available phosphorus (A.P).
• Stepwise regression:-
In addition stepwise linear regression revealed that the most closely variable related to seed yield is SMB-P and the most closely variable related to A.P is SMB-P.
Finally, it could be concluded that, for obtaining a high, good quality and quantity, economically in the same time and saving soil from hazards of the high doses of mineral fertilizers, we recommended that sunflower plants must be irrigated every 15 day and fertilized with mineral P fertilizer in conjunction with PSB and sprayed with EDTA-Zn under the same conditions of the study. The equations of polynomial and stepwise regression confirmed this conclusion.