Managing Scarce Water Resources in Agriculture in West Asia and North Africa - Restorative Redevelopment of Devastated Ecocultural Landscapes - page 460

2.5

Rain water Irrigation water

2

1.5

1

0.5

0

N0 N50 N100 N150

Nitrogen Application Rate (kg N/ha)

FIGURE 22.9 Different levels of nitrogen in northern Syria. Gains in water productivity

for wheat grain.

2

Rainfed Full SI 1/3 SI 2/3 SI

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

CHAM1 LAHN CHAM4 MEXIPAK

Wheat Varieties

FIGURE 22.10 Average 4-year rainwater and supplemental irrigation (SI) water produc-
tivity for durum and bread wheat varieties grown in northern Syria. (Cham1 and Lahn are
durum; Mexipak and Cham4 are bread wheat varieties). (Oweis, 2001, unpublished data.)

the same time, they should maintain some degree of drought resistance, and hence
express a good plasticity. Figure (22.10) shows the variations in the response of two
durum and two bread wheat varieties to various water management options
Using both Mendelian breeding techniques and modern genetic engineering,
new crop varieties can be developed that can increase the water use efficiency
while maintaining or even increasing the yield levels. For example, through breed-
ing, winter chickpea and drought-resistant barley varieties that use substantially
less water have been developed. The chickpea crop is traditionally sown in the