Assessing genetic gain and diversity in Ethiopian bread wheat across six decades

Assessing breeding progress and genetic diversity in released varieties is crucial for informing future crop improvement strategies. This study evaluated genetic gain and diversity in 49 Ethiopian wheat varieties released over six decades (1967-2021). Significant yield increases were observed, with 'Shaki' showing the highest gain. However, the average annual genetic gain was modest (0.90% under irrigated, 0.69% under rain-fed). The recent released bread wheat variety ″Shaki″ exhibited a 48.6% increase in grain yield under irrigated conditions and a 37.1% increase under rain-fed conditions over the oldest variety, "Lakech". Genetic diversity analysis revealed a decline in heterozygosity and a skewed allele distribution, suggesting potential inbreeding within the breeding program. Population structure analysis indicated a shared genetic background across decades. The low genetic gain and declining diversity highlight the need for strategies to enhance genetic diversity and incorporate novel yield-associated traits to achieve sustainable genetic improvement in Ethiopian wheat breeding.