To optimize the EMS-induced mutagenesis technology of forage oat （Avena sativa L.） and improve mutagenic efficiency， seeds of Oat cultivar ‘Qinghai 444’ and ‘Zhongtian No. 4’ were used as materials in this study. PEG osmotic priming was combined with EMS chemical mutagenesis to screen for optimum compound mutagenesis conditions for forage oat. Based on the germination characteristics and seedling traits of the M₁ generation in the two oat cultivars， the pretreatment conditions of 20% PEG for 3 h and 10% PEG for 6 h were found to promote seedling growth. The optimal EMS treatment conditions were 1% EMS for 16 h for ‘Zhongtian No.4’ and 0.75% EMS for 16 h for ‘Qinghai 444’. Through a comprehensive analysis of field agronomic traits at the milk stage in the M₂ generation after combined PEG and EMS treatments， it was found that 30% PEG for 3 h combined with the optimal EMS treatment produced the best results for developing germplasm with high-yield potential in both cultivars. Under these conditions， the mutagenesis efficiencies of the M₂ population were 2.40% for ‘Zhongtian No. 4’ and 1.26% for ‘Qinghai 444’， respectively， and a total of 22 germplasm lines with high-yield potential were obtained. These results provide a rich material basis for subsequent oat breeding.

Forage Oat  /  Mutagenesis  /  EMS  /  PEG  /  High yield  /  Germplasm