用渗透胁迫鉴定小麦种子萌发期抗旱性的方法分析

本以聚乙二醇(PEG)-6000、甘露醇和蔗糖作为渗透剂模拟水分胁迫，胁迫溶液渗透势范围在-0．25MPa到-1．50MPa，分析适于进行小麦种子水分胁迫萌发试验的条件，以鉴定小麦萌发期的抗旱性。结果表明，蔗糖溶液易诱发霉茵，胚芽不能正常生长。渗透势为-0．25MPa的PEG-6000及-0．50MPa的甘露醇胁迫已经显抑制了胚芽伸长；-0．50MPa的PEG-6000及-1．00MPa的甘露醇显抑制种子萌发，随着胁迫强度增加，种子相对发芽率及胚芽长度减小，主要是因为渗透胁迫降低了种子吸水速度，胚芽的相对含水量和渗透势均低。在渗透势相同的胁迫条件下，PEG-6000对小麦种子萌发各项检测值的抑制作用均大于甘露醇。如果目的是通过鉴定小麦种子在高渗溶液中的萌发情况，评价萌发期的抗旱性。选用-0．50MPa的PEG-6000或-1．00MPa的甘露醇较为理想，若同时考虑降低试验成本，则应首选-0．50MPa的PEG-6000。

Methods for Identifying Drought Resistance at Germination Stage of Wheat by Osmotic Stress

Polyethylene glycol (PEG)-6000, mannitol and sucrose were employed as osmotica for simulating water stress to identify drought resistance at germination stage of wheat. Three osmotica with osmotic potential from -0.25MPa to 1.50MPa were compared. Germinal bud growth in sucrose was inhibited because of molding and stress. Germinal bud elongation was inhibited in -0.25MPa PEG-6000 and -0.50MPa mannitol. Germination percentage significantly decreased in -0.50MPa PEG-6000 and -1.00MPa mannitol. Both of germination percentage and germinal bud length decreased with the increase of osmotic stress because the speed of water absorbing by grains was slow in osmotic stress solutions, and further resulted in lower grain relative water content (RWC) and lower osmotic potential than in water. All parameters associated with germination decreased more seriously in PEG-6000 than in mannitol at the same osmotic potential. For the purpose of evaluating drought resistance of wheat genotypes by identifying germination percentage in osmotic stress solution, -0.50MPa PEG-6000 or -1.00MPa mannitol is ideal, but -0.50MPa PEG-6000 should be preferred if the experiment cost is considered.