PEG胁迫对西伯利亚冰草种子萌发及幼苗生理特性的影响

摘要

以PEG-6000模拟干旱胁迫,分析西伯利亚冰草种子发芽率、发芽势、胚根和胚芽长及三叶期幼苗相对电导率、丙二醛和游离脯氨酸含量的动态变化规律.结果表明:1)高渗透势PEG溶液(-0.2,-0.4 MPa)能够促进种子萌发,在-0.4 MPa时,发芽率和发芽势均达到峰值.2)高渗透势PEG溶液(-0.2,-0.4,-0.6 MPa)对胚根伸长具有一定的促进作用,-0.4 MPa最大,但对胚芽表现出一定的抑制作用.3)随着渗透势的降低,发芽率、发芽势、胚根长和胚芽长不断下降,胚根/胚芽的比值持续上升.4)3叶期幼苗相对电导率、丙二醛和脯氨酸含量随胁迫强度的增加,胁迫时间的延长持续增加,相对电导率、丙二醛含量除了-0.4 MPa,1d处理外,其他处理均极显著(p＜0.01)高于对照,脯氨酸含量各处理均极显著(p＜0.01)高于对照,相对电导率、丙二醛和脯氨酸这3个指标均可作为抗旱性评价指标.%The dynamic variation rules of Agropyron sibiricum seed germination rate,germination potential,radicle length,embryonic bud length and the relative electric conductivity,content of malondialdehyde and free proline for seedling at trefoil stage were analyzed under drought stress simulated by PEG in this experiment.The results showed that:1) PEG solution with high osmotic potential (-0.2 and-0.4 MPa) could promote the seed germination while the germination rate and germination potential peak at-0.4 MPa.2) PEG solution with high osmotic potential (-0.2,-0.4 and-0.6 MPa) had a certain promoting effect on radicle elongation,with the maximum promoting effect at -0.4 MPa,but showed a certain inhibitory effect on the embryonic bud elongation.3) With the decrease of osmotic potential,the germination rate,germination potential,radicle length and embryonic bud length decreased constantly while the ratio of radicle to embryonic bud increased continuously.4) The relative electric conductivity,content of malondialdehyde and proline of seedling at trefoilstage increased continuously with the increase of stress intensity and its time lengthening.The relative electric conductivity and the malondialdehyde content were significantly higher than those of the control group(p＜0.01) except for the treatment at-0.4 MPa,1 d.The proline content of all treatment was extremely higher than that of the control group (p＜0.01).In conclusion,the relative electric conductivity,malondialdehyde and proline could all be used as drought resistance evaluation indexes.