Evaluation of Ethiopian Durum and Bread Wheat Genotypes for Stem Rust Adult Plant Resistance

Abstract

Stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. and Henn) incurs significant yield losses in wheat in Ethiopia, as  most commercial varieties lack sufficient resistance to the rust. New resistance sources identification and incorporation  of resistance has continued. Combining adult plant and seedling resistances based Sr-resistance genes is foundation for  durable stem rust resistant variety providing effective rust protection. Thirty two durum wheat lines (DW) and 30  bread wheat genotypes (BW) were evaluated for stem rust seedling resistance. Twenty nine DW and 15 BW with  heterogeneous seedling infection (2+3-) and > 3- were further evaluated for stem rust adult plant field resistance.  Seedling infection types (ITs), host plant responses, terminal disease severity (TDS), coefficient of infection (CI) and  relative area under disease progress curve (r-AUDPC) were used for evaluating adult plant resistance. Four DW lines  7974-2, 203680-2, 7974-1, 203831-2 and one advanced BW line ETB9550 expressed low TDS/field response of 15MS-25MS,  CI of 12-20 and r-AUDPC of 12-22%. These lines had susceptible seedling infection types and were regarded  as highly slow rusting. Likewise, DW lines 5454-1, 6112-1, 203726-2, 203855-2 and 203899-1 and BW lines  ETBW9652 and ETBW9313 with >3- ITs showed r-AUDPC, CI and TDS/response of 31-70%, 28-36 and 30S-45MSS,  respectively, were grouped to genotypes with moderate slow rusting resistance. Slow rusting resistant wheat genotypes  identified from the present study can be used for developing durable stem rust resistant wheat cultivars  once they are postulated for their inherent resistance Sr-genes.