美容杜鹃种子萌发及对干旱渗透胁迫的响应研究

本研究以美容杜鹃为试材，探讨了PEG模拟干旱渗透胁迫下美容杜鹃种子萌发情况及美容杜鹃幼苗的叶绿素含量、POD酶活性、MDA含量的变化，来评价美容杜鹃的抗旱性。结果表明,随着干旱渗透胁迫程度的增大，种子发芽率、发芽势下降,200 g/L的PEG胁迫下，发芽率、发芽势只能达到对照的21.98%、22.73%，250 g/L的PEG下，种子完全没有萌发。另外，在用不同浓度的PEG处理幼苗时，各指标在250 g/L时变化最明显。MDA含量在处理第2 d、第8 d与对照相比增加104.73%、148.94%；总叶绿素含量在处理第4天与对照相比下降86.44%；POD酶活性在处理第4天与对照相比提高50.10%。总之，随着胁迫浓度的增大和时间的延长，美容杜鹃种子的发芽率、发芽势均逐渐下降，美容杜鹃幼苗的渗透胁迫损伤程度变大，尤以250 g/L时最为明显。

Seed Germination and Response to Drought Osmotic Stress in Rhododendron calophytum

In this study,Rhododendron calophytum was used as the test material to investigate the germination of rhododendron seeds and the changes of chlorophyll content,POD enzyme activity and MDA content of rhododendron seedlings under PEG simulated drought stress,and to evaluate the drought resistance of Rhododendron calophytum.The results showed that seed germination rate and germination potential decreased with the increase of drought stress.Under 200 g/L PEG stress, the germination rate and germination potential could only reach 21.98% and 22.73% ,respectively, compared with the control,and the seeds did not germinate at all under 250 g/L PEG stress.In addition, when the seedlings were treated with different concentrations of PEG, the changes of each index were the most obvious at 250 g/L.MDA content increased by 104.73% and 148.94% on the second day and eighth day after treatment compared with the control. Total chlorophyll content decreased by 86.44% compared with the control on the fourth day. POD activity increased by 50.10% compared with the control on the fourth day.In conclusion, with the increase of stress concentration and the extension of time,the germination rate and germination potential of Rhododendron calophytum seeds gradually decreased, the damage degree of Rhododendron calophytum seedlings became greater under drought stress,especially at 250 g/L.