Abstract: 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 displayed 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 seedling 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 germination 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 germination stages. These findings emphasize the need for effective management strategies to mitigate the impact of drought on plant growth and survival.

Key words: radical emergence, plumule emergence, seedling growth, Leymus chinensis, drought stress, rewatering