Abstract: 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 M? generation.

Key words: Hybrid Pennisetum, Heavy-ion irradiation, Mutation breeding, Cold-tolerant germplasm, Mutagenesis system

摘要： 杂交狼尾草（Pennisetum glaucum × P. purpureum）是重要的高产优质牧草，但耐寒性差，限制了其在北方及高纬度地区的推广应用。重离子是一种较新型的诱变源，在牧草育种中的应用尚不多。本研究以杂交狼尾草‘邦得1号’种子为材料，设50，100，150，200，300 Gy重离子辐射处理，系统分析苗期生长表型及低温胁迫下生理指标，进行综合评价。旨在探讨其诱变效应，建立狼尾草种子重离子辐射诱变技术体系，创制耐寒新种质。结果显示，重离子辐射对杂交狼尾草表现出明显剂量效应，其中100 Gy处理下能在保证成苗率的同时显著提高可溶性糖含量和超氧化物歧化酶、过氧化物酶活性，降低膜损伤水平，半致死温度最低，表现出最优耐寒性并且诱变效率较高。本研究通过实验室和大田2个尺度、结合主成分分析、隶属函数分析、田间存活率和大田越冬率等多个维度综合评价，筛选出3株诱变当代潜在耐寒突变体。

关键词: 杂交狼尾草, 重离子辐射, 诱变育种, 耐寒种质, 诱变技术体系