Abstract:
Wheat stem rust caused by Puccinia graminis f. sp. Tritici (Pgt) is one of the most important diseases
of wheat worldwide. In Ethiopia, the disease is quite common in humid and warm wheat growing
environments of central and southeastern Ethiopia. The understanding of the resistance genes to
Puccinia graminis f.sp.tritici is one of the most important premises for reasonable, effective
application and distribution of the resistance source in the comprehensive management of wheat stem
rust. Field and greenhouse experiments were conducted to determine the slow-rusting resistance of
wheat genotypes; and investigate the wheat stem rust resistance spectra in bread wheat genotypes at
seedling stage during 2021/22. A total of 121 bread wheat genotypes were included in the study. The
field experiment was carried at Sinana and Agarfa locations while the seedling test was carried out in
the greenhouse facilities at Debre Zeit Agricultural Research Center. The bread wheat genotypes and
checks were exposed to seven dominant individual stem rust races (TTTTF, TTKTT, TTKTTF, TTRTF,
TKTTF, TKKTF, and TTKSK (UG99)-the isolates were initially obtained from Ambo Agricultural
Research Center. In matched with 20 Near isogenic genotypes (NILs) 4 single Sr resistance genes
Sr11, 36, 30, and 24 were postulated in the 15 wheat genotypes, 20 genotypes were resistant and 88
genotypes had unidentified Sr genes. A total of 28 wheat genotypes showed intermediate and
susceptible reactions at seedling stage (2+ to 3-, 3+ to 4). From these 3 varieties like Kingberd,
Pavon 76, and Sofumer showed slow-rusting resistance with less than 300 low area under disease
progressive curve (AUDPC). The 15 genotypes depict true slow rusting which identified based on field
evaluation and seedling test. Therefore, the 15 wheat genotypes with Sr11, 36, 30, and 24 sr genes, -
and the 15 true slow rusting genotypes identified from field evaluations can be used in future breeding
programs for durable slow rusting resistance. Further studies should include more NILs and markers
to successfully identify seedling and Adult plant resistance (APR) Sr resistance genes in the wheat
genotypes.
