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The objective of this study was to identify tolerant and susceptible genotypes of bread wheat under different irrigation treatments and determine the type of gene action and some genetic parameters in three bread wheat crosses; (Line 1 × Line 2), (Line1 × Giza 171) and (Misr 2 × Line 3) under normal irrigation and water stress treatments. Genetic materials included six populations (P1, P2, F1, F2, BC1 and BC2) for each cross. Positive and high significant values for heterotic effects relative to the mid- parent of grain yield were found for the second (Line1 × Giza 171) and third cross (Misr 2 × Line 3) under both irrigation treatments, while positive values heterosis for better parent detected for the third cross under both irrigation treatments. Non-allelic interaction was found for all studied characters in all the crosses under both irrigation treatments. Dominance effects were greater than the additive gene effect. Dominance × dominance gene interaction was higher in magnitude than additive × additive and additive × dominance for most characters under both irrigation treatments, indicating that these characters greatly affected by dominance and non-allelic interactions. Heritability in the broad sense was high for all the studied characters in three crosses under both irrigation treatments, while narrow sense heritability estimates were moderate to high for all the studied characters under both irrigation treatments. In general, the highest values of grain yield/plant were in the third cross (Misr2 × Line 3) under both irrigation treatments, based on tolerance index (Line 1) and (Line 2) are the most tolerant for water stress and the first cross (Line1 × Line2) was the most one for water stress tolerant, so this cross is recommended under water stress conditions. |
