SCREENING BREAD WHEAT GENOTYPES FOR DROUGHT TOLERANCE 1- GERMINATION, RADICAL GROWTH AND MEAN PERFORMANCE OF YIELD AND ITS COMPONENTS

Seed germination decreased as osmotic potential became more negative. Inhibition of seed germination was greatest under the lowest osmotic potential, - 1.5 MPa. Cumulative germination after ten days ratiged from 52.6% to 97.9% for the control compared to 27.4% to 69.8% at -1.5 MPa indicating more pronounced differences among genotypes at the lower osmotic potentials. Accordingly, ten bread wheat genotypes were selected and significantly varied for all traits tested under different irrigation treatments in each location. Reduction percentages for different studied traits under water stress treatments relative to control treatment was detected and susceptibility index was also calculated for each genotype under severe water stress treatment. The superior lines No. s 27,13,15 and 5 had the highest grain yield/plant under severe treatment in both locations. The higher yielding capability of these genotypes obtained under drought stress may be primarily due to its higher yield potential under nonstress conditions and maximize production of number of spikes/plant and number of grains/spike under water stress conditions. The main effect of irrigation treatments was not significant for susceptibility index (S) of grain yield/plant under both environments tested, indicating that (S) was not affected by increasing water stress intensity. S values ranged from 0.924 for G1 to 1.54 for the local check variety G10.