不同萌发阶段的羊草种子对干旱-复水的响应

Response of Leymus chinensis seeds to drought stress and rewatering in different germination stages

干旱胁迫对不同萌发阶段种子的作用直接影响到植物的定植和生长发育。本研究对萌动、发芽和生长阶段的羊草种子进行不同时间的干旱胁迫后复水,分析了不同萌发阶段种子萌发和幼苗生长对干旱胁迫的响应。结果表明:复水后,干旱胁迫发生在萌动阶段的羊草种子萌发率为30%~56%,发生在发芽阶段为7%~33%;生长阶段进行干旱胁迫前萌发率为31%~62%,但干旱胁迫会造成羊草幼苗死亡,导致最终存活率为2%~41%,因此相同干旱胁迫强度对不同萌发阶段种子萌发率的影响程度为:生长阶段>发芽阶段>萌动阶段。此外,随着萌发期干旱胁迫时间的延长,种子萌发率呈下降趋势,超出种子所能承受的范围时,已萌动的种子也会死亡,且死亡率随干旱胁迫天数的增加呈上升趋势。萌动阶段的羊草种子干旱6 d后复水发芽率与对照没有显著差异,而发芽阶段干旱2 d发芽率显著降低,生长阶段羊草幼苗耐干旱天数阈值为6 d。本研究揭示了干旱胁迫对不同萌发阶段羊草种子的不利影响,需要制定有效的管理策略来减轻干旱对植物生长和生存的影响。

Drought stress on seeds at different germination stages can influence plant establishment and growth.To examine this effect,we conducted an experiment on Leymus chinensis seeds in three stages:radicle emergence,plumule emergence,and seedling establishment,which were subjected to varying durations of drought stress.The germination and growth responses were observed.The results showed that under drought stress,L.chinensis dis-played different germination percentages across the three stages.The germination percentage ranged from 30%to 56%in the radicle emergence stage,but decreased to 7%-33%in the plumule emergence stage.In the seedling establishment stage,germination percentage before drought stress ranged from 31%to 62%.However,in the seed-ling establishment stage,drought stress could lead to seedling death,resulting in a final survival percentage of only 2%-41%.Therefore,the impact of drought stress on seed germination varied across different stages.The seedling establishment stage was most affected,followed by the plumule emergence stage,and then the radicle emergence stage.Furthermore,as the duration of drought stress increased,the germination percentage steadily declined.Once the stress surpassed a certain threshold,the seeds lost their vitality.The mortality rate increased with increasing days of drought stress.Specifically,in the radicle emergence stage,there were no significant differences in germi-nation percentage between seeds subjected to 6 days of drought stress and the control group(CK).In the plumule emergence stage,a significant reduction in germination percentage was observed after just 2 days of drought stress.The drought resistant threshold for L.chinensis was determined to be 6 days during the seedling establishment stage.In summary,our results highlight the detrimental effects of drought stress on L.chinensis seeds at different germina-tion stages.These findings emphasize the need for effective management strategies to mitigate the impact of drought on plant growth and survival.