Why this book; For wheat improvement, drought tolerance, tissue culture techniques, bio-statistical approaches, desert cultivation; Immature embryo culture technique and field experiments were carried out to define the most desirable bread wheat varieties and their immature embryos calli tested under different mannitol concentrations, i.e., 0, 6, 9, and 12 osmotic pressures. Also, comparing that with their behaviour in field experiment of withholding irrigation regime at heading stage. Also, determine the influence of the two water regimes on growth, yield and yield components. Correlation coefficients between some callus traits and yield and its components had been done.