RESISTANCE OF BREAD WHEAT (Triticum aestivum L. Thell) GENOTYPES TO WHEAT STEM RUST (Puccinia graminis f. sp. tritici ) IN HIGHLANDS OF BALE ZONE, OROMIYA, ETHIOPIA

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.