Abstract: This study aimed to elucidate the regulatory mechanisms of microbial fertilizer seed soaking on the seed germination and seedling physiology of oats under the combined stress of low temperature and drought. Using the seeds of ‘Qinghai Sweet Oat’ as the experimental material， polyethylene glycol （PEG-6000） was employed to simulate drought stress at five levels （0.0， -0.2， -0.4， -0.8， -1.0 MPa）， combined with a low-temperature environment （day/night temperature of 10/5 ℃ and a photoperiod of 10 h light/14 h dark）. The stress resistance effects of seed soaking treatments with Bacillus licheniformis fertilizer （DY）， EM microbial fertilizer （EM）， and compound microbial fertilizer （FH） were systematically analyzed. The results indicated that seed soaking with microbial fertilizers mitigated the inhibitory effect of the combined stress on the seed germination of ‘Qinghai Sweet Oat’. Among them， the seeds treated with FH performed well in terms of germination rate， germination index， seedling height， radicle length， soluble inclusions and antioxidant enzyme activity. Under the -0.8 MPa stress treatment， the germination rate of the FH treatment reached 84.00%， and the activity of superoxide dismutase （SOD） increased by 68.85%， while the activity of peroxidase （POD） reached 82.67 U·g^-1. Under the -1.0 MPa stress treatment， the fresh weight of seedlings in the FH treatment was 0.30 g， the soluble sugar content was 12.24 mg·g^-1， and the activities of SOD and POD were 78.67 and 76.67 U·g^-1， respectively. Membership function analysis showed that the order of stress-resistance of the microbial fertilizer treatments was FH>EM>DY. Correlation analysis confirmed that the germination parameters were significantly positively correlated with antioxidant enzyme activities， and all the above mentioned parameters （except seedling height） were negatively correlated with malondialdehyde （MDA） content. In conclusion， soaking the seeds of ‘Qinghai Sweet Oat’ with a 0.1 g·mL^-1 compound microbial fertilizer at room temperature for 24 h can effectively enhance the emergence rate under the combined stress of low temperature and drought by strengthening antioxidant metabolism and osmotic adjustment ability， providing technical support for stress resistant cultivation of oats in alpine regions.

Key words: High altitude areas, Biofungal fertilizer, Combined stress of low temperature and drought, Germination index, Membership function

摘要： 为阐明微生物菌肥浸种对低温干旱复合胁迫下燕麦种子萌发及幼苗生理的调控机制，本研究以‘青海甜燕麦’（‘Qinghai sweet oat’）种子为材料，采用聚乙二醇（PEG-6000）模拟干旱胁迫（0.0，-0.2，-0.4，-0.8，-1.0 MPa），结合低温环境（昼/夜温度为10/5°C，光周期为10 h光照/14 h黑暗），系统分析地衣芽孢杆菌菌肥（DY）、EM菌肥（EM）及复合微生物菌肥（FH）浸种处理的抗逆效应。结果表明，微生物菌肥浸种缓解了低温干旱复合胁迫对‘青海甜燕麦’种子萌发的抑制作用。其中，FH处理的种子在发芽率、发芽指数、幼苗高度、胚根长度、可溶性内含物及抗氧化酶活性等方面表现优良。在-0.8 MPa胁迫下，FH处理发芽率高达84.00%，超氧化物歧化酶（Superoxide dismutase， SOD）活性提高68.85%，过氧化物酶（Peroxidase， POD）活性达到82.67 U·g^-1。在-1.0 MPa胁迫下，FH处理幼苗鲜重为0.30 g，可溶性糖（Soluble sugar， SS）含量为12.24 mg·g^-1，SOD与POD活性分别为78.67和76.67 U·g^-1。隶属函数分析显示菌肥处理抗逆性排序为FH>EM>DY，相关性分析证实发芽参数与抗氧化酶活性呈显著正相关，除幼苗高度与丙二醛（Malondialdehyde， MDA）呈显著负相关，其余参数均与MDA呈负相关。综上，本研究表明‘青海甜燕麦’种子在播种时采用0.1 g·mL^-1复合微生物菌肥室温浸种24 h，可通过增强抗氧化代谢与渗透调节能力，有效提高低温干旱复合胁迫下的出苗率，为高寒区燕麦抗逆栽培提供技术支撑。

关键词: 高海拔地区, 生物菌肥, 低温干旱复合胁迫, 萌发指数, 隶属函数