Özet:

Two field trials were conducted at three sites in Egypt to study the effect of deficit irrigation on wheat yield and consumptive water use. The first trial was conducted at Beni Sweif governorate, where data was available from 1998/99 to 2001/02 growing seasons. The second trial was conducted at two sites i.e. El-Monofia and Demiatte governorates, where data were available for the 2005/06 growing season for 3 and 4 farms, respectively. The objectives of this research were: (i) to validate the Yield-Stress model for wheat yield data at three sites in Egypt; (ii) to predict wheat yield under reducing the amount of applied irrigation water; (iii) to test the capability of the Yield-Stress model in irrigation scheduling and conserving water. The Yield-Stress model was validated under the application of the full irrigation amounts at the three sites and under deducting about 20% of full irrigation at El-Monofia and Demiatte sites. Afterward, the model was used to predict wheat yield under deducting 30% of full irrigation at the three sites. Results showed that there was a good agreement between measured and predicted yield at the three sites. Results also indicated that under deducting 30% of full irrigation, wheat yield will be reduced by less than 6% at the three sites. Furthermore, using the model in studying the depletion of readily available water from the root zone at the three sites could help in saving up to 24% of the applied irrigation water with almost no wheat yield losses.

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