Hybrid Pennisetum （Pennisetum glaucum × P. purpureum） is an important high-yield and high-quality forage grass； however， its poor cold tolerance restricts its cultivation and utilization in northern and high-latitude regions. Heavy-ion irradiation is a relatively new mutagenic approach and has been rarely applied in forage breeding. In this study， seeds of the hybrid Pennisetum cultivar ‘Bangde No.1’ were treated with heavy-ion irradiation at doses of 50， 100， 150， 200， and 300 Gy. Seedling growth traits and physiological responses under low-temperature stress were systematically evaluated to investigate the mutagenic effects of heavy-ion irradiation， establish a heavy-ion mutagenesis system for hybrid Pennisetum seeds， and develop novel cold-tolerant germplasm. The results showed that heavy-ion irradiation exerted a clear dose-dependent effect on hybrid Pennisetum. Among the treatments， 100 Gy not only maintained a high seedling establishment rate but also significantly increased soluble sugar content and the activities of superoxide dismutase （SOD） and peroxidase （POD）， reduced membrane damage， and resulted in the lowest semi-lethal temperature （LT₅₀） of plant mutants， indicating the strongest cold tolerance and relatively high mutagenic efficiency. Based on a comprehensive evaluation integrating laboratory and field assessments， principal component analysis， membership function analysis， field survival rate， and field overwintering rate， three potential cold-tolerant mutants were identified from the M₁ generation.

Hybrid Pennisetum  /  Heavy-ion irradiation  /  Mutation breeding  /  Cold-tolerant germplasm  /  Mutagenesis system