Characterizations of bread wheat germplasms for slow rusting to stem rust through field and seedling phenotyping approaches at Kulumsa, South Eastern Ethiopia
Abstract
Getnet Muche Abebele*, Alemu Ayele Zerihun, Hawila Tesfaye Dilgasa
Wheat (Triticum aestivum L.) is a principal staple crop worldwide, including in Ethiopia, where it receives top governmental priority among major cereals to ensure food security and promote export potential. However, biotic stresses, particularly yellow and stem rusts caused by Puccinia striiformis f. sp. tritici and Puccinia graminis f. sp. tritici, respectively, continue to pose serious threats to sustainable wheat production, leading to annual yield losses worth tens of millions of USD. The emergence and spread of highly virulent stem rust races such as Ug99 (TTKSK) and its variants have further exacerbated the problem by rapidly overcoming existing host resistance genes across major wheat-growing regions of Ethiopia. This study aimed to evaluate thirty three advanced bread wheat genotypes and twelve released commercial varieties for field-based slow rusting and seedling-stage resistance to stem rust. The field experiment was conducted under an augmented design, while the seedling test was arranged in a Completely Randomized Design (CRD) under greenhouse conditions at Kulumsa agricultural research center during the 2023/2024 off-season. Results indicated that 25 (75.75%) advanced genotypes and 2 (16.66%) released varieties exhibited low final rust severity (FRS<30%) and average coefficient of infection (ACI<20%) under field conditions. However, only 11 (33.33%) advanced genotypes—namely EBW170072, EBW160066, EBW170172, EBW170051, EBW160002, EBW222680, EBW170056, EBW170059, EBW170058, EBW160065, and EBW224096—and 2 (16.66%) released varieties (Abay and Boru) demonstrated higher infection types at the seedling stage, confirming their partial or slow rusting resistance. These promising genotypes can serve as valuable parental sources for resistance breeding in regional wheat improvement programs or be advanced to regional yield trials for the development of high-yielding, stem rust–resistant cultivars. Such efforts are essential to counter the continually evolving stem rust races and safeguard national wheat productivity.