Abstract: Based on multi-year， multi-site field trials combined with physiological and photosynthetic measurements， in this study we evaluated the cold tolerance and production adaptability of a new Pennisetum purpureum line ‘Yunmu No.1’（YM-1）， in comparison with two local predominant cultivars， P. purpureum ‘Dehong’（DH） and P. purpureum ×P. typhoideum ‘Reyan No.4’（RY-4）. The results indicated that the cold tolerance of the tested materials， in descending order， was YM-1>DH>RY-4. YM-1 had the lowest semi-lethal temperature （LT₅₀） of -5.413℃. Under low-temperature stress， its superoxide dismutase （SOD） activity increased significantly by 237.12%， while malondialdehyde （MDA） content increased only marginally by 1.25%， indicating that it primarily responds to low temperature through an antioxidant mechanism. In contrast， DH mainly responded to low temperature by accumulating osmotic adjustment substances， including soluble sugar （+76.77%） and proline （+60.24%）. RY-4 exhibited weak responses in both antioxidant and osmotic adjustment mechanisms， with an MDA increase of 43.07%. The freezing injury index during the first-frost period was consistent with the above physiological ranking. At an altitude of 2350 m， YM-1 showed the highest sprouting rate （50.4%； i.e.， the proportion of stumps with newly sprouted tillers） and regreening rate （43.0%）. Its three-year average hay yield was 6.1% and 11.3% higher than those of DH and RY-4， respectively. In conclusion， ‘Yunmu No.1’ possesses both strong cold tolerance and high and stable yield potential， making it suitable for cultivation in complex environments below 2000 m elevation on the Yunnan Plateau. A comprehensive evaluation method based on LT₅₀， MDA content， SOD activity， field freezing injury phenotype， and natural overwintering capacity can be used for the systematic identification of cold tolerance in Pennisetum purpureum.

Key words: New Pennisetum purpureum line, Cold tolerance, Production adaptability, Freezing injury physiological characteristics, Photosynthetic characteristics under low temperature

摘要： 基于多年多点田间试验与生理光合测定，本研究以当地主栽品种‘德宏’（DH）和‘热研4号’（RY-4）象草为对照，系统评估了象草新品系‘云牧1号’（YM-1）的耐寒性与生产适应性。结果表明，参试材料的耐寒性强弱顺序为YM-1>DH>RY-4。YM-1的低温半致死温度（-5.413℃）最低，低温胁迫下超氧化物歧化酶活性显著上升237.12%，丙二醛含量仅微增1.25%，主要以抗氧化机制响应低温；DH则主要通过积累可溶性糖（+76.77%）和脯氨酸（+60.24%）等渗透调节物质响应低温；RY-4抗氧化与渗透调节响应均较弱，丙二醛含量增幅达43.07%。初霜期冻害指数与上述生理指标排序一致。在海拔2350 m条件下，YM-1的萌蔸率（地下芽萌发成新株丛的比例）（50.4%）与返青率（43.0%）均最高，3年平均干草产量比DH和RY-4分别高出6.1%和11.3%。综上，‘云牧1号’兼具耐寒性和高产稳产潜力，适宜在云南高原区2000 m以下复杂环境中推广；基于低温半致死温度、丙二醛含量、超氧化物歧化酶活性、田间冻害表型及自然越冬能力的综合评价方法，可用于象草耐寒性的系统鉴定。

关键词: 象草新品系, 耐寒性, 生产适应性, 冻害生理特性, 低温光合特性