INHERITANCE OF STRIPE RUST RESISTANCE IN FIVE EGYPTIAN BREAD WHEAT CULTIVARS CROSSED TO FOUR Yr,s

Abstract

The inheritance of resistance in 5 Egyptian bread wheat cultivars (Triticum aestivum, L.) crossed to 4 Yr"s was studied. These parents, F1"s and F2"s were tested under greenhouse conditions at seedling stage against pathotype (race) 230E18 of Puccinia striiformis Westend. All of the tested parents and F1"s exhibited a susceptible phenotype. All crosses, F2"s plant populations were segregated into digenic pairs. The dominance was in the side of susceptibility while resistance genes were recessive. On the other hand, under field conditions, at adult plant stage against more virulent race mixtures of that pathogen, the tested (cv.) parents, Oxly (Yr 6 +APR), Yr18, Giza 168, Sakha 61 and Sids1 showed low rust severity, while Yr 2, Yr 9 ; Sakha 8 and Sakha 69 showed high rust severity. The F1"s showed that all of the crosses exhibited low rust severity except for four crosses i.e. Yr