Rusts continue to cause significant losses in grain yield of wheat in Iraq. Substitution of susceptible cultivars with resistant ones is an important step in reducing the vulnerability of the wheat crop. The present study represents a breeding program to develop high yielding bread wheat cultivars with resistance to brown rust and yellow rust. The performance of 265 spring wheat genotypes representing an international bread wheat-screening nursery from CIMMYT were evaluated in different agro-ecological zones in comparison with local commercial cultivars. Adult plant stage screening of the materials for brown rust and yellow rust reaction under inoculated conditions for three successive seasons identified 29 resistant and 59 moderately resistant genotypes, and 79 genotypes out-yielded the local cultivars. The selected lines were comprehensively evaluated for grain yield potential and disease response in different locations and agro-systems. Among 13 genotypes line 172 was selected for higher grain yield than local commercial cultivars in the presence and absence of both diseases. Mean coefficients of infection on line 172 were 0.57 and 5.35 to brown rust and yellow rust, respectively. It was also moderately resistant to common bunt. Yield potential of the new cv. Alaa was 9-20% higher than the commercial local cultivars Araz, Tamuz 2 and Adana. Alaa was registered and released by the National Committee for Registration and Release of Agricultural Cultivars according to order no. 39, 30/10/2017 as a new cultivar with high yield potential and resistance to brown rust and yellow rust. Great emphasis was made on multiplication and delivery of seeds to farmers. Grain yield potential of Alaa on a farm scale is 3,372 Kg/ha under rain-fed conditions and 5,024 Kg/ha under irrigated conditions.
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This study was conducted to detect new races of Puccinia striiformis f. sp. tritici in Iraq. Trap nurseries were planted in different locations throughout the main wheat growing areas. Stripe rust severities and infection types on each genotype were recorded at different stages of crop development. Yellow rust samples collected from commercial wheat fields at different locations were sent to the Global Rust Center for race analysis. Local adult plant tests indicated virulence for host genes Yr2, Yr6, Yr7, Yr9, Yr18, YrA, Yr20, Yr21, Yr27, Yr28, Yr29, and Yr31 at the adult plant stage in Sulaimania, and virulence to Yr2, Yr6, Yr7, Yr9, YrSD, YrSP, YrA, Yr21, Yr27, Yr28, and Yr31 at Nineveh. Virulence on lines carrying Yr5, Yr6, Yr7, Yr9, Yr20, Yr21, Yr27, Yr28 and Yr31 were recorded in Babylon and to Yr2, Yr5, Yr6, Yr7, Yr9, Yr18, YrA, Yr20, Yr25, Yr28, Yr29, and Yr31 at Diyala. Of 21 YR samples sent to GRRC for race analysis, cultures were recovered from ten. Two Pst pathotypes (races) were identified; one was virulent to Yr2, Yr6, Yr7, Yr8, Yr9, Yr27, and AvS whereas the other had additional virulence to Yr25 (Strubes Dickkopf). None was virulent for Yr5. Both pathotypes were aggressive based on Milus et al. measures.