Maize ( Zea mays L. ) is one of the most important basic cereal crops in the world. In Egypt . Maize was grown in about 1.975.400 million faddans in 2004 and produced about 20.9? ardab l Fadden (one Fadden = 4200 miE and one ardab = 140 kg ) (Report by FAO 2004 ). Maize crop is known to be sensitive to available soil moisture especially during reproductive stage therefore yield decrease resulting from soil moisture deficit depends upon numerous factors. such as the growth stage at which the moisture deficit develops, the severity and duration of water deficiency, and the susceptibility of the examined genotype { Denmead and Shaw, 1960 Lorena et at, 1987) .According to the difference in conditions. like irrigation.r it is more impertant to study and recommend plot size in controlled irrigation treatment and drought treatment besides the field plot technique dealing with various factors essential for a properly planned Agriculture field experiment. some of these factors are size . shape. and arrangement of plots as experimental units together with the effects of these units on each other