the past decades, lightweight, hand-held, portable, and battery operated infrared thermometers (IRT) became Corn (Zea mays L.) grown under a Mediterranean semiarid climate available. Infrared thermometers can rapidly measure requires supplemental irrigation to maximize the grain yield. Since the cost of irrigation application has been increasing, elimination of canopy temperatures over large areas. The theory of unnecessary irrigation applications would improve economics of corn IRT operation (Fuchs and Tanner, 1966; Fuchs et al., production. There has been much interest in the crop water stress 1967; Hatfield, 1990; Gardner and Shock, 1989); and index (CWSI) as a potential tool for irrigation scheduling and yield (Gardner et al., 1992a) and temperature effects in infraestimation. An experiment was conducted to monitor and quantify red thermometry (Jackson and Idso, 1969) have been water stress, and to develop parameters for irrigation scheduling and discussed. In the 1980s, the use of IRT become more grain yield of summer-grown corn as a function of CWSI under Mediroutine in irrigation scheduling when Idso et al. (1981a) terranean semiarid cropping conditions. Three irrigation treatments developed and demonstrated an empirical method for were based on replenishing the 0.9-m deep root zone to field capacity using the crop water stress index (CWSI). when the soil water level dropped to 25, 50, and 75% of available Idso et al. (1981a) observed a linear relationship bewater holding capacity (AWHC). A dryland treatment was also included. The lower (nonstressed) and upper (stressed) baselines were

Egypt produces half of the 20 million tons of wheat that it consumes with irrigation and imports the other half. Egypt is also the world's largest importer of wheat. The population of Egypt is currently growing at 2.2% annually, and projections indicate that the demand for wheat will triple by the end of the century. Combining multi-crop and -climate models for different climate change scenarios with recent trends in technology, we estimated that future wheat yield will decline mostly from climate change, despite some yield improvements from new technologies. The growth stimulus from elevated atmospheric CO 2 will be overtaken by the negative impact of rising temperatures on crop growth and yield. An ongoing program to double the irrigated land area by 2035 in parallel with crop intensification could increase wheat production and make Egypt self-sufficient in the near future, but would be insufficient after 2040s, even with modest population growth. Additionally, the demand for irrigation will increase from 6 to 20 billion m 3 for the expanded wheat production, but even more water is needed to account for irrigation efficiency and salt leaching (to a total of up to 29 billion m 3 ). Supplying water for future irrigation and producing sufficient grain will remain challenges for Egypt.

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