关键词: 豆科牧草, 干旱胁迫, 种子萌发, 隶属函数, 种子活力

Abstract: [Objective] To assess the effects of simulated drought stress with polyethylene glycol （PEG） on seed germination of Lespedeza davurica, Medicago ruthenica, and Coronilla varia. [Method] PEG solutions with concentrations of 0, 5%, 10%, 15%, 20% and 25% were used to simulate drought stress, and the seed germination experiments of the above three leguminous forage species were conducted. The germination percentage, germination index, mean germination time, and seedling vigor index of their seeds were analyzed, and their drought resistance were comprehensively evaluated to explore the germination properties under drought stress. [Result] The germination percentage, germination index and seedling vigor index of Lespedeza davurica and Medicago ruthenica seeds significantly （P<0.05） declined with the aggravation of drought stress, but their mean germination time significantly （P<0.05） increased. When PEG concentration reached 25%, the Lespedeza davurica seeds lost their vigor. The germination percentage, germination index and seedling vigor index of Coronilla varia seeds were significantly （P<0.05） higher than those of the control at 5%-10% of PEG concentrations, then dropped as the PEG concentrations increased. The comprehensive evaluation by membership function method demonstrated that the order of drought resistance of the three tested leguminous forage species at seed germination stage was Coronilla varia > Medicago ruthenica > Lespedeza davurica. [Conclusion] Simulated drought stress with PEG inhibits the germination of Lespedeza davurica and Medicago ruthenica seeds. PEG at low concentrations （≤10%） promote the germination of Coronilla varia seeds, however, higher concentrations （≥15%） have the reverse effect. Coronilla varia seeds have a stronger germination capacity in comparison with Medicago ruthenica and Lespedeza davurica seeds under drought stress.

Key words: leguminous forages, drought stress, seed germination, membership function, seed vigor